Genivia Home Documentation
README.md Source File

updated Sun Feb 16 2020 by Robert van Engelen
 
README.md
Go to the documentation of this file.
1 
2 C and C++ XML Data Bindings {#mainpage}
3 ===========================
4 
5 [TOC]
6 
7 Introduction {#intro}
8 ============
9 
10 This article presents a detailed overview of the gSOAP XML data bindings for C
11 and C++. The XML data bindings for C and C++ are extensively used with gSOAP
12 Web services to serialize C and C++ data in XML as part of the SOAP/XML Web
13 services payloads. Also REST XML with gSOAP relies on XML serialization of C
14 and C++ data via XML data bindings.
15 
16 The major advantage of XML data bindings is that your application data is
17 always **type safe** in C and C++ by binding XML schema types to C/C++ types.
18 So integers in XML are bound to C integers, strings in XML are bound to C or
19 C++ strings, complex types in XML are bound to C structs or C++ classes, and so
20 on. The structured data you create and accept will fit the data model and is
21 **static type safe**. In other words, by leveraging strong typing in C/C++,
22 your XML data meets **XML schema validation requirements** and satisfies **XML
23 interoperability requirements**.
24 
25 In fact, gSOAP data bindings are more powerful than simply representing C/C++
26 data in XML. The gSOAP tools implement true and tested **structure-preserving
27 serialization** of C/C++ data in XML, including the serialization of cyclic
28 graph structures with id-ref XML attributes. The gSOAP tools also generate
29 routines for deep copying and deep deletion of C/C++ data structures to
30 simplify memory management. In addition, C/C++ structures are deserialized
31 into managed memory, managed by the gSOAP `soap` context.
32 
33 At the end of this article two examples are given to illustrate the application
34 of XML data bindings. The first simple example <i>`address.cpp`</i> shows how to use
35 wsdl2h to bind an XML schema to C++. The C++ application reads and writes an
36 XML file into and from a C++ "address book" data structure as a simple example.
37 The C++ data structure is an STL vector of address objects. The second example
38 <i>`graph.cpp`</i> shows how C++ data can be accurately serialized as a tree, digraph,
39 and cyclic graph in XML. The digraph and cyclic graph serialization rules
40 implement SOAP 1.1/1.2 multi-ref encoding with id-ref attributes to link
41 elements through IDREF XML references, creating a an XML graph with pointers to
42 XML nodes that preserves the structural integrity of the serialized C++ data.
43 
44 These examples demonstrate XML data bindings only for relatively simple data
45 structures and types. The gSOAP tools support more than just these type of
46 structures to serialize in XML. There are practically no limits to the
47 serialization of C and C++ data types in XML.
48 
49 Also the support for XML schema (XSD) components is unlimited. The wsdl2h tool
50 maps schemas to C and C++ using built-in intuitive mapping rules, while
51 allowing the mappings to be customized using a <i>`typemap.dat`</i> file with mapping
52 instructions for wsdl2h.
53 
54 The information in this article is applicable to gSOAP 2.8.26 and greater that
55 support C++11 features. However, C++11 is not required. The material and the
56 examples in this article use plain C and C++, until the point where we
57 introduce C++11 smart pointers and scoped enumerations. While most of the
58 examples in this article are given in C++, the concepts also apply to C with
59 the exception of containers, smart pointers, classes and their methods. None
60 of these exceptions limit the use of the gSOAP tools for C in any way.
61 
62 The data binding concepts described in this article were first envisioned in
63 1999 by Prof. Robert van Engelen at the Florida State University. An
64 implementation was created in 2000, named "stub/skeleton compiler". The first
65 articles on its successor version "gSOAP" appeared in 2002. The principle of
66 mapping XSD components to C/C++ types and vice versa is now widely adopted in
67 systems and programming languages, including Java web services and by C# WCF.
68 
69 We continue to be committed to our goal to empower C/C++ developers with
70 powerful autocoding tools for XML. Our commitment started in the very early
71 days of SOAP by actively participating in
72 [SOAP interoperability testing](http://www.whitemesa.com/interop.htm),
73 participating in the development and testing of the
74 [W3C XML Schema Patterns for Databinding Interoperability](http://www.w3.org/2002/ws/databinding),
75 and continues by contributing to the development of
76 [OASIS open standards](https://www.oasis-open.org) in partnership with leading
77 IT companies in the world.
78 
79 🔝 [Back to table of contents](#)
80 
81 Notational Conventions {#conventions}
82 ======================
83 
84 The typographical conventions used by this document are:
85 
86 * `Courier` denotes C and C++ source code.
87 
88 * <i>`Courier`</i> denotes XML content, JSON content, file and path names, and URIs.
89 
90 * <b>`Courier`</b> denotes HTTP content, text file content, and shell commands with command line options and arguments.
91 
92 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
93 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to
94 be interpreted as described in RFC-2119.
95 
96 🔝 [Back to table of contents](#)
97 
98 Mapping WSDL and XML schemas to C/C++ {#tocpp}
99 =====================================
100 
101 To convert WSDL and XML schemas (XSD files) to code, we use the wsdl2h command
102 on the command line (or command prompt), after opening a terminal. The wsdl2h
103 command generates the data binding interface code that is saved to a special
104 Web services and data bindings interface header file with extension <i>`.h`</i>
105 that contains the WSDL service declarations and the data binding interface
106 declarations in a familiar C/C++ format:
107 
108  wsdl2h [options] -o file.h ... XSD and WSDL files ...
109 
110 This command converts WSDL and XSD files to C++ (or pure C with
111 <b>`wsdl2h -c`</b>) and saves the data binding interface to a interface header
112 file <i>`file.h`</i> that uses familiar C/C++ syntax extended with `//gsoap`
113 [directives](#directives) and annotations. Notational conventions are used in
114 the data binding interface to declare serializable C/C++ types and functions
115 for Web service operations.
116 
117 The WSDL 1.1/2.0, SOAP 1.1/1.2, and XSD 1.0/1.1 standards are supported by the
118 gSOAP tools. In addition, the most popular WS specifications are also
119 supported, including WS-Addressing, WS-ReliableMessaging, WS-Discovery,
120 WS-Security, WS-Policy, WS-SecurityPolicy, and WS-SecureConversation.
121 
122 This article focusses mainly on XML data bindings. XML data bindings for C/C++
123 bind XML schema types to C/C++ types. So integers in XML are bound to C
124 integers, strings in XML are bound to C or C++ strings, complex types in XML
125 are bound to C structs or C++ classes, and so on.
126 
127 A data binding is dual, meaning supporting a two way direction for development.
128 Either you start with WSDLs and/or XML schemas that are mapped to equivalent
129 C/C++ types, or you start with C/C++ types that are mapped to XSD types.
130 Either way, the end result is that you can serialize C/C++ types in XML such
131 that your XML is an instance of XML schema(s) and is validated against these
132 schema(s).
133 
134 This covers all of the following standard XSD components with their optional
135 attributes and properties:
136 
137 XSD component | attributes and properties
138 -------------- | -------------------------
139 schema | targetNamespace, version, elementFormDefault, attributeFormDefault, defaultAttributes
140 attribute | name, ref, type, use, default, fixed, form, targetNamespace, wsdl:arrayType
141 element | name, ref, type, default, fixed, form, nillable, abstract, substitutionGroup, minOccurs, maxOccurs, targetNamespace
142 simpleType | name
143 complexType | name, abstract, mixed, defaultAttributesApply
144 all | *n/a*
145 choice | minOccurs, maxOccurs
146 sequence | minOccurs, maxOccurs
147 group | name, ref, minOccurs, maxOccurs
148 attributeGroup | name, ref
149 any | minOccurs, maxOccurs
150 anyAttribute | *n/a*
151 
152 And also the following standard XSD directives are covered:
153 
154 directive | description
155 ---------- | -----------
156 import | Imports a schema into the importing schema for referencing
157 include | Include schema component definitions into a schema
158 override | Override by replacing schema component definitions
159 redefine | Extend or restrict schema component definitions
160 annotation | Annotates a component
161 
162 The XSD facets and their mappings to C/C++ are:
163 
164 XSD facet | maps to
165 -------------- | -------
166 enumeration | `enum`
167 simpleContent | class/struct wrapper with `__item` member
168 complexContent | class/struct
169 list | `enum*` bitmask (`enum*` enumerates a bitmask up to 64 bits)
170 extension | class/struct inheritance/extension
171 restriction | `typedef` and class/struct inheritance/redeclaration
172 length | `typedef` with restricted content length annotation
173 minLength | `typedef` with restricted content length annotation
174 maxLength | `typedef` with restricted content length annotation
175 minInclusive | `typedef` with numerical value range restriction annotation
176 maxInclusive | `typedef` with numerical value range restriction annotation
177 minExclusive | `typedef` with numerical value range restriction annotation
178 maxExclusive | `typedef` with numerical value range restriction annotation
179 precision | `typedef` with pattern annotation (pattern used for output, but input is not validated)
180 scale | `typedef` with pattern annotation (pattern used for output, but input is not validated)
181 totalDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
182 fractionDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
183 pattern | `typedef` with pattern annotation (define `soap::fsvalidate` callback to validate patterns)
184 union | string with union of value
185 
186 All primitive XSD types are supported, including but not limited to the
187 following XSD types:
188 
189 XSD type | maps to
190 ---------------- | -------
191 any/anyType | `_XML` string with literal XML content (or enable DOM with wsdl2h option `-d`)
192 anyURI | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
193 string | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
194 boolean | `bool` (C++) or `enum xsd__boolean` (C)
195 byte | `char` (i.e. `int8_t`)
196 short | `short` (i.e. `int16_t`)
197 int | `int` (i.e. `int32_t`)
198 long | `LONG64` (i.e. `long long` and `int64_t`)
199 unsignedByte | `unsigned char` (i.e. `uint8_t`)
200 unsignedShort | `unsigned short` (i.e. `uint16_t`)
201 unsignedInt | `unsigned int` (i.e. `uint32_t`)
202 unsignedLong | `ULONG64` (i.e. `unsigned long long` and `uint64_t`)
203 float | `float`
204 double | `double`
205 integer | string or `#import "custom/int128.h"` to use 128 bit `xsd__integer`
206 decimal | string or `#import "custom/long_double.h"` to use `long double`
207 precisionDecimal | string
208 duration | string or `#import "custom/duration.h"` to use 64 bit `xsd__duration`
209 dateTime | `time_t` or `#import "custom/struct_tm.h"` to use `struct tm` for `xsd__dateTime`
210 time | string or `#import "custom/long_time.h"` to use 64 bit `xsd__time`
211 date | string or `#import "custom/struct_tm_date.h"` to use `struct tm` for `xsd__date`
212 hexBinary | special class/struct `xsd__hexBinary`
213 base64Binary | special class/struct `xsd__base64Binary`
214 QName | `_QName` string (URI normalization rules are applied)
215 
216 All other primitive XSD types not listed above are mapped to strings, by
217 wsdl2h generating a `typedef` to string for these types. For example,
218 <i>`xsd:token`</i> is bound to a C++ or C string:
219 
220 ~~~{.cpp}
221  typedef std::string xsd__token; // C++
222  typedef char *xsd__token; // C (wsdl2h option -c)
223 ~~~
224 
225 This associates a compatible value space to the type with the appropriate XSD
226 type name used by the soapcpp2-generated serializers.
227 
228 It is possible to remap types by adding the appropriate mapping rules to
229 <i>`typemap.dat`</i> as we will explain in more detail in the next section.
230 
231 Imported custom serializers are intended to extend the C/C++ type bindings when
232 the default binding to string is not satisfactory to your taste and if the
233 target platform supports these C/C++ types. To add custom serializers to
234 <i>`typemap.dat`</i> for wsdl2h, see [adding custom serializers](#custom) below.
235 
236 🔝 [Back to table of contents](#)
237 
238 Using typemap.dat to customize data bindings {#typemap}
239 ============================================
240 
241 Use a <i>`typemap.dat`</i> file to redefine namespace prefixes and to customize type
242 bindings for the the generated header files produced by the wsdl2h tool. The
243 <i>`typemap.dat`</i> is the default file processed by wsdl2h. Use <b>`wsdl2h -tfile.dat`</b>
244 option <b>`-tfile.dat`</b> to specify a different mapping file <i>`file.dat`</i>.
245 
246 Declarations in <i>`typemap.dat`</i> can be broken up over multiple lines by
247 continuing on the next line by ending each line to be continued with a
248 backslash <b>`\`</b>. The limit is 4095 characters per line, whether the line is
249 broken up or not.
250 
251 🔝 [Back to table of contents](#)
252 
253 XML namespace bindings {#typemap1}
254 ----------------------
255 
256 The wsdl2h tool generates C/C++ type declarations that use `ns1`, `ns2`, etc.
257 as schema-binding URI prefixes. These default prefixes are generated somewhat
258 arbitrarily for each schema targetNamespace URI, meaning that their ordering
259 may change depending on the WSDL and XSD order of processing with wsdl2h.
260 
261 Therefore, it is **strongly recommended** to declare your own prefix for each
262 schema URI in <i>`typemap.dat`</i> to reduce maintaince effort of your code. This
263 is more robust when anticipating possible changes of the schema(s) and/or the
264 binding URI(s) and/or the tooling algorithms.
265 
266 The first and foremost important thing to do is to define prefix-URI bindings
267 for our C/C++ code by adding the following line(s) to our <i>`typemap.dat`</i> or make
268 a copy of this file and add the line(s) that bind our choice of prefix name to
269 each URI:
270 
271  prefix = "URI"
272 
273 For example, to use `g` as a prefix for the "urn:graph" XML namespace:
274 
275  g = "urn:graph"
276 
277 This produces `g__name` C/C++ type names that are bound to the "urn:graph"
278 schema by association of `g` to the generated C/C++ types.
279 
280 This means that <i>`<g:name xmlns:g="urn:graph">`</i> is parsed as an instance of a
281 `g__name` C/C++ type. Also <i>`<x:name xmlns:x="urn:graph">`</i> parses as an
282 instance of `g__name`, because the prefix <i>`x`</i> has the same URI value
283 <i>`urn:graph`</i>. Prefixes in XML have local scopes (like variables in a block).
284 
285 The first run of wsdl2h will reveal the XML namespace URIs, so you do not need
286 to search WSDLs and XSD files for all of the target namespaces. Just copy them
287 from the generated header file after the first run into <i>`typemap.dat`</i> for
288 editing.
289 
290 @note Only define a namespace prefix once in <i>`typemap.dat`</i>. That is, do not
291 use the same prefix for multiple XML namespace URIs. This is to avoid
292 namespace conflicts that may cause failed builds and failures in XML parsing
293 and XML schema validation.
294 
295 🔝 [Back to table of contents](#)
296 
297 XSD type bindings {#typemap2}
298 -----------------
299 
300 Custom C/C++ type bindings can be declared in <i>`typemap.dat`</i> to associate C/C++
301 types with specific schema types. These type bindings have four parts:
302 
303  prefix__type = declaration | use | ptruse
304 
305 where
306 
307 - <b>`prefix__type`</b> is the schema type to be customized (the <b>`prefix__type`</b> name
308  uses the common double underscore naming convention);
309 
310 - <b>`declaration`</b> declares the C/C++ type in the wsdl2h-generated header file.
311  This part can be empty if no explicit declaration is needed;
312 
313 - <b>`use`</b> is an optional part that specifies how the C/C++ type is used in the
314  code. When omitted, it is the same as <b>`prefix__type`</b>;
315 
316 - <b>`ptruse`</b> is an optional part that specifies how the type is used as a pointer
317  type. By default it is the <b>`use`</b> type name with a <b>`*`</b> or C++11
318  <b>`std::shared_ptr<type>`</b> when enabled (see further below). If <b>`use`</b> is already a
319  pointer type by the presence of a <b>`*`</b> in the <b>`use`</b> part, then the default
320  <b>`ptruse`</b> type is the same as the <b>`use`</b> type (that is, no double
321  pointers <b>`**`</b> will be created in this case).
322 
323 For example, to map <i>`xsd:duration`</i> to a `long long` (`LONG64`) type that holds
324 millisecond duration values, we can use the custom serializer declared in
325 <i>`gsoap/custom/duration.h`</i> by adding the following line to <i>`typemap.dat`</i>:
326 
327  xsd__duration = #import "custom/duration.h"
328 
329 Here, we omitted the second and third parts, because `xsd__duration` is the
330 name that wsdl2h uses for this type in our generated code so we should leave
331 the <b>`use`</b> part unspecified. The third part is omitted to let wsdl2h use
332 `xsd__duration *` for pointers or `std::shared_ptr<xsd__duration>` if smart
333 pointers are enabled.
334 
335 To map <i>`xsd:string`</i> to `wchar_t*` wide strings for C source code output:
336 
337  xsd__string = | wchar_t* | wchar_t*
338 
339 For C++ we can use the `std::wstring` wide string:
340 
341  xsd__string = | std::wstring
342 
343 Note that the first part is empty, because these types do not require a
344 declaration. A <b>`ptruse`</b> part is also defined for `wchar_t*`, but this
345 is actually needed because the wsdl2h tool recognizes that the <b>`use`</b>
346 part `wchar_t*` is already a pointer. By contrast, when using 8-bit strings,
347 it is recommended to use the `SOAP_C_UTFSTRING` flag to enable UTF-8 formatted
348 strings.
349 
350 When the auto-generated declaration should be preserved but the <b>`use`</b> or
351 <b>`ptruse`</b> parts replaced, then we use an ellipsis for the declaration part:
352 
353  prefix__type = ... | use | ptruse
354 
355 This is useful to map schema polymorphic types to C types for example, where we
356 need to be able to both handle a base type and its extensions as per schema
357 extensibility. Say we have a base type called <i>`ns:base`</i> that is extended, then
358 we can remap this to a C type that permits referening the extended types via a
359 `void*` as follows:
360 
361  ns__base = ... | int __type_base; void*
362 
363 such that `__type_base` and `void*` will be used to (de)serialize any data
364 type, including base and its derived types. The `__type_base` integer is set
365 to a `SOAP_TYPE_T` value to indicate what type of data the `void*` pointer
366 points to.
367 
368 🔝 [Back to table of contents](#)
369 
370 Custom serializers for XSD types {#custom}
371 --------------------------------
372 
373 In the previous part we saw how a custom serializer is used to bind
374 <i>`xsd:duration`</i> to a `long long` (`LONG64` or `int64_t`) type to store millisecond
375 duration values:
376 
377  xsd__duration = #import "custom/duration.h"
378 
379 The `xsd__duration` type is an alias of `long long` (`LONG64` or `int64_t`).
380 
381 While wsdl2h will use this binding declared in <i>`typemap.dat`</i>
382 automatically, you will also need to compile <i>`gsoap/custom/duration.c`</i>.
383 Each custom serializer has an interface header file to be imported into another
384 interface header file that declares the custom type for soapcpp2 and a
385 serializer implementation file written in C, which should be compiled with the
386 application. You can compile these in C++ (rename files to <i>`.cpp`</i> if
387 needed).
388 
389 A custom serializer is declared in an interface header file for soapcpp2 using
390 `extern typedef`. The typedef name declared is serializable, whereas the
391 type on which it is based is not serializable. This declaration can be
392 combined with `volatile` when the type should not be redeclared, see
393 [volatile classes and structs](#toxsd9-2). For example, the custom serializer
394 for `struct tm` is the type `xsd__datetime` declared as follows in
395 `gsoap/custom/struct_tm.h`:
396 
397 ~~~{.cpp}
398  extern typedef volatile struct tm
399  {
400  int tm_sec; ///< seconds (0 - 60)
401  int tm_min; ///< minutes (0 - 59)
402  int tm_hour; ///< hours (0 - 23)
403  int tm_mday; ///< day of month (1 - 31)
404  int tm_mon; ///< month of year (0 - 11)
405  int tm_year; ///< year - 1900
406  int tm_wday; ///< day of week (Sunday = 0) (NOT USED)
407  int tm_yday; ///< day of year (0 - 365) (NOT USED)
408  int tm_isdst; ///< is summer time in effect?
409  char* tm_zone; ///< abbreviation of timezone (NOT USED)
410  } xsd__dateTime;
411 ~~~
412 
413 Another example is `xsd__duration` as a custom serializer for the C++11 type
414 `std::chrono::nanoseconds`:
415 
416 ~~~{.cpp}
417  extern typedef class std::chrono::nanoseconds xsd__duration;
418 ~~~
419 
420 Next, we present all pre-defined custom serializers that are available to you.
421 
422 🔝 [Back to table of contents](#)
423 
424 ### xsd:integer {#custom-1}
425 
426 The wsdl2h tool maps <i>`xsd:integer`</i> to a string by default. To map <i>`xsd:integer`</i> to
427 the 128 bit big int type `__int128_t`:
428 
429  xsd__integer = #import "custom/int128.h"
430 
431 The `xsd__integer` type is an alias of `__int128_t`.
432 
433 @warning Beware that the <i>`xsd:integer`</i> value space of integers is in principle
434 unbounded and values can be of arbitrary length. A value range fault
435 `SOAP_TYPE` (value exceeds native representation) or `SOAP_LENGTH` (value
436 exceeds range bounds) will be thrown by the deserializer if the value is out of
437 range.
438 
439 Other XSD integer types that are restrictions of <i>`xsd:integer`</i>, are
440 <i>`xsd:nonNegativeInteger`</i> and <i>`xsd:nonPositiveInteger`</i>, which are further restricted
441 by <i>`xsd:positiveInteger`</i> and <i>`xsd:negativeInteger`</i>. To bind these types to
442 `__int128_t` add the following definitions to <i>`typemap.dat`</i>:
443 
444  xsd__nonNegativeInteger = typedef xsd__integer xsd__nonNegativeInteger 0 : ;
445  xsd__nonPositiveInteger = typedef xsd__integer xsd__nonPositiveInteger : 0 ;
446  xsd__positiveInteger = typedef xsd__integer xsd__positiveInteger 1 : ;
447  xsd__negativeInteger = typedef xsd__integer xsd__negativeInteger : -1 ;
448 
449 Or simply uncomment these definitions in <i>`typemap.dat`</i> when you are using the
450 latest gSOAP releases.
451 
452 @note If `__int128_t` 128 bit integers are not supported on your platform and if it
453 is certain that <i>`xsd:integer`</i> values are within 64 bit value bounds for your
454 application's use, then you can map this type to `LONG64`:
455 
456  xsd__integer = typedef LONG64 xsd__integer;
457 
458 @note Again, a value range fault `SOAP_TYPE` or `SOAP_LENGTH` will be thrown by
459 the deserializer if the value is out of range.
460 
461 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/int128.c`</i> with your project.
462 
463 @see Section [numerical types](#toxsd5).
464 
465 🔝 [Back to table of contents](#)
466 
467 ### xsd:decimal {#custom-2}
468 
469 The wsdl2h tool maps <i>`xsd:decimal`</i> to a string by default. To map <i>`xsd:decimal`</i> to
470 extended precision floating point:
471 
472  xsd__decimal = #import "custom/long_double.h" | long double
473 
474 By contrast to all other custom serializers, this serializer enables `long
475 double` natively without requiring a new binding name (`xsd__decimal` is NOT
476 defined).
477 
478 If your system supports <i>`quadmath.h`</i> quadruple precision floating point
479 `__float128`, you can map <i>`xsd:decimal`</i> to `xsd__decimal` that is an alias of
480 `__float128`:
481 
482  xsd__decimal = #import "custom/float128.h"
483 
484 @warning Beware that <i>`xsd:decimal`</i> is in principle a decimal value with arbitraty
485 lengths. A value range fault `SOAP_TYPE` will be thrown by the deserializer if
486 the value is out of range.
487 
488 In the XML payload the special values <i>`INF`</i>, <i>`-INF`</i>, <i>`NaN`</i>
489 represent plus or minus infinity and not-a-number, respectively.
490 
491 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_double.c`</i> with your
492 project.
493 
494 @see Section [numerical types](#toxsd5).
495 
496 🔝 [Back to table of contents](#)
497 
498 ### xsd:dateTime {#custom-3}
499 
500 The wsdl2h tool maps <i>`xsd:dateTime`</i> to `time_t` by default.
501 
502 The trouble with `time_t` when represented as 32 bit `long` integers is that it
503 is limited to dates between 1970 and 2038. A 64 bit `time_t` is safe to use if
504 the target platform supports it, but lack of 64 bit `time_t` portability may
505 still cause date range issues.
506 
507 For this reason `struct tm` should be used to represent wider date ranges. This
508 custom serializer avoids using date and time information in `time_t`. You get
509 the raw date and time information. You only lose the day of the week
510 information. It is always Sunday (`tm_wday=0`).
511 
512 To map <i>`xsd:dateTime`</i> to `xsd__dateTime` which is an alias of `struct tm`:
513 
514  xsd__dateTime = #import "custom/struct_tm.h"
515 
516 If the limited date range of `time_t` is not a problem but you want to increase
517 the time precision with fractional seconds, then we suggest to map <i>`xsd:dateTime`</i>
518 to `struct timeval`:
519 
520  xsd__dateTime = #import "custom/struct_timeval.h"
521 
522 If the limited date range of `time_t` is not a problem but you want to use the
523 C++11 time point type `std::chrono::system_clock::time_point` (which internally
524 uses `time_t`):
525 
526  xsd__dateTime = #import "custom/chrono_time_point.h"
527 
528 Again, we should make sure that the dates will not exceed the date range when
529 using the default `time_t` binding for <i>`xsd:dateTime`</i> or when binding
530 <i>`xsd:dateTime`</i> to `struct timeval` or to `std::chrono::system_clock::time_point`.
531 These are safe to use in applications that use <i>`xsd:dateTime`</i> to record date
532 stamps within a given window. Otherwise, we recommend the `struct tm` custom
533 serializer.
534 
535 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm.c`</i> with your
536 project.
537 
538 You could even map <i>`xsd:dateTime`</i> to a plain string (use `char*` with C and
539 `std::string` with C++). For example:
540 
541  xsd__dateTime = | char*
542 
543 @see Section [date and time types](#toxsd7).
544 
545 🔝 [Back to table of contents](#)
546 
547 ### xsd:date {#custom-4}
548 
549 The wsdl2h tool maps <i>`xsd:date`</i> to a string by default. We can map <i>`xsd:date`</i> to
550 `struct tm`:
551 
552  xsd__date = #import "custom/struct_tm_date.h"
553 
554 The `xsd__date` type is an alias of `struct tm`. The serializer ignores the
555 time part and the deserializer only populates the date part of the struct,
556 setting the time to 00:00:00. There is no unreasonable limit on the date range
557 because the year field is stored as an integer (`int`).
558 
559 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm_date.c`</i> with your
560 project.
561 
562 @see Section [date and time types](#toxsd7).
563 
564 🔝 [Back to table of contents](#)
565 
566 ### xsd:time {#custom-5}
567 
568 The wsdl2h tool maps <i>`xsd:time`</i> to a string by default. We can map <i>`xsd:time`</i> to
569 an `unsigned long long` (`ULONG64` or `uint64_t`) integer with microsecond time
570 precision:
571 
572  xsd__time = #import "custom/long_time.h"
573 
574 This type represents 00:00:00.000000 to 23:59:59.999999, from `0` to an upper
575 bound of `86399999999`. A microsecond resolution means that a 1 second
576 increment requires an increment of 1000000 in the integer value. The serializer
577 adds a UTC time zone.
578 
579 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_time.c`</i> with your
580 project.
581 
582 @see Section [date and time types](#toxsd7).
583 
584 🔝 [Back to table of contents](#)
585 
586 ### xsd:duration {#custom-6}
587 
588 The wsdl2h tool maps <i>`xsd:duration`</i> to a string by default, unless <i>`xsd:duration`</i>
589 is mapped to a `long long` (`LONG64` or `int64_t`) type with with millisecond
590 (ms) time duration precision:
591 
592  xsd__duration = #import "custom/duration.h"
593 
594 The `xsd__duration` type is a 64 bit signed integer that can represent
595 106,751,991,167 days forwards (positive) and backwards (negative) in time in
596 increments of 1 ms (1/1000 of a second).
597 
598 Rescaling of the duration value by may be needed when adding the duration value
599 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
600 depending on the platform and possible changes to `time_t`.
601 
602 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
603 value to a `std::chrono::system_clock::time_point` value. To use
604 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
605 
606  xsd__duration = #import "custom/chrono_duration.h"
607 
608 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
609 backwards in time in increments of 1 ns (1/1,000,000,000 of a second).
610 
611 Certain observations with respect to receiving durations in years and months
612 apply to both of these serializer decoders for <i>`xsd:duration`</i>.
613 
614 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/duration.c`</i> with your
615 project.
616 
617 @see Section [time duration types](#toxsd8).
618 
619 🔝 [Back to table of contents](#)
620 
621 Custom Qt serializers for XSD types {#qt}
622 -----------------------------------
623 
624 The gSOAP distribution includes several custom serializers for Qt types. Also
625 Qt container classes are supported, see
626 [the built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE](#typemap5).
627 
628 This feature requires gSOAP 2.8.34 or higher and Qt 4.8 or higher.
629 
630 Each Qt custom serializer has an interface header file for soapcpp2 and a C++
631 implementation file to be compiled with your project.
632 
633 Other Qt primitive types that are Qt `typedef`s of C/C++ types do not require a
634 custom serializer.
635 
636 🔝 [Back to table of contents](#)
637 
638 ### xsd:string {#qt-1}
639 
640 To use Qt strings instead of C++ strings, add the following definition to
641 <i>`typemap.dat`</i>:
642 
643  xsd__string = #import "custom/qstring.h"
644 
645 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qstring.cpp`</i> with your
646 project.
647 
648 🔝 [Back to table of contents](#)
649 
650 ### xsd:base64Binary {#qt-2}
651 
652 To use Qt byte arrays for <i>`xsd:base64Binary`</i> instead of the
653 `xsd__base64Binary` class, add the following definition to <i>`typemap.dat`</i>:
654 
655  xsd__base64Binary = #import "custom/qbytearray_base64.h"
656 
657 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_base64.cpp`</i> with
658 your project.
659 
660 🔝 [Back to table of contents](#)
661 
662 ### xsd:hexBinary {#qt-3}
663 
664 To use Qt byte arrays for <i>`xsd:hexBinary`</i> instead of the `xsd__base64Binary`
665 class, add the following definition to <i>`typemap.dat`</i>:
666 
667  xsd__hexBinary = #import "custom/qbytearray_hex.h"
668 
669 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_hex.cpp`</i> with
670 your project.
671 
672 🔝 [Back to table of contents](#)
673 
674 ### xsd:dateTime {#qt-4}
675 
676 To use Qt QDateTime for <i>`xsd:dateTime`</i>, add the following definition to
677 <i>`typemap.dat`</i>:
678 
679  xsd__dateTime = #import "custom/datetime.h"
680 
681 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdatetime.cpp`</i> with
682 your project.
683 
684 🔝 [Back to table of contents](#)
685 
686 ### xsd:date {#qt-5}
687 
688 To use Qt QDate for <i>`xsd:date`</i>, add the following definition to
689 <i>`typemap.dat`</i>:
690 
691  xsd__date = #import "custom/qdate.h"
692 
693 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdate.cpp`</i> with your
694 project.
695 
696 🔝 [Back to table of contents](#)
697 
698 ### xsd:time {#qt-6}
699 
700 To use Qt QDate for <i>`xsd:time`</i>, add the following definition to
701 <i>`typemap.dat`</i>:
702 
703  xsd__time = #import "custom/qtime.h"
704 
705 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qtime.cpp`</i> with your
706 project.
707 
708 🔝 [Back to table of contents](#)
709 
710 Class/struct member additions {#typemap3}
711 -----------------------------
712 
713 All generated classes and structs can be augmented with additional
714 members such as methods, constructors and destructors, and private members:
715 
716  prefix__type = $ member-declaration
717 
718 For example, we can add method declarations and private members to a class, say
719 `ns__record` as follows:
720 
721  ns__record = $ ns__record(const ns__record &); // copy constructor
722  ns__record = $ void print(); // a print method
723  ns__record = $ private: int status; // a private member
724 
725 Method declarations cannot include any code, because soapcpp2's input permits
726 only type declarations, not code.
727 
728 🔝 [Back to table of contents](#)
729 
730 Replacing XSD types by equivalent alternatives {#typemap4}
731 ----------------------------------------------
732 
733 Type replacements can be given to replace one type entirely with another given
734 type:
735 
736  prefix__type1 == prefix__type2
737 
738 This replaces all `prefix__type1` by `prefix__type2` in the wsdl2h output.
739 
740 @warning Do not agressively replace types, because this can cause XML schema
741 validation to fail when a value-type mismatch is encountered in the XML input.
742 Therefore, only replace similar types with other similar types that are wider
743 (e.g. `short` by `int` and `float` by `double`).
744 
745 🔝 [Back to table of contents](#)
746 
747 The built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE {#typemap5}
748 -----------------------------------------------------------------
749 
750 The <i>`typemap.dat`</i> <b>`$CONTAINER`</b> variable defines the container type to use in
751 the wsdl2h-generated declarations for C++, which is `std::vector` by default.
752 For example, to use `std::list` as the container in the wsdl2h-generated
753 declarations we add the following line to <i>`typemap.dat`</i>:
754 
755  $CONTAINER = std::list
756 
757 Also a Qt container can be used instead of the default `std::vector`, for
758 example `QVector`:
759 
760  [
761  #include <QVector>
762  ]
763  $CONTAINER = QVector
764 
765 To remove containers, use <b>`wsdl2h -s`</b>. This also removes `std::string`,
766 but you can re-introduce `std::string` with
767 <b>`xsd__string = | std::string`</b> in <i>`typemap.dat`</i>.
768 
769 The <i>`typemap.dat`</i> <b>`$POINTER`</b> variable defines the smart pointer to use in the
770 wsdl2h-generated declarations for C++, which replaces the use of `*` pointers.
771 For example:
772 
773  $POINTER = std::shared_ptr
774 
775 Not all pointers in the generated output are replaced by smart pointers by
776 wsdl2h, such as pointers as union members and pointers as struct/class members
777 that point to arrays of values.
778 
779 @note The standard smart pointer `std::shared_ptr` is generally safe to use.
780 Other smart pointers such as `std::unique_ptr` and `std::auto_ptr` may cause
781 compile-time errors when classes have smart pointer members but no copy
782 constructor (a default copy constructor). A copy constructor is required for
783 non-shared smart pointer copying or swapping.
784 
785 Alternatives to `std::shared_ptr` of the form `NAMESPACE::shared_ptr` can be
786 assigned to <b>`$POINTER`</b> when the namespace `NAMESPACE` also implements
787 `NAMESPACE::make_shared` and when the shared pointer class provides `reset()`
788 and`get()` methods and the dereference operator. For example Boost
789 `boost::shared_ptr`:
790 
791  [
792  #include <boost/shared_ptr.hpp>
793  ]
794  $POINTER = boost::shared_ptr
795 
796 The user-defined content between <b>`[`</b> and <b>`]`</b> ensures that we include the Boost
797 header files that are needed to support `boost::shared_ptr` and
798 `boost::make_shared`.
799 
800 The variable <b>`$SIZE`</b> defines the type of array sizes, which is `int` by
801 default. For example, to change array size types to `size_t`:
802 
803  $SIZE = size_t
804 
805 Permissible types are `int` and `size_t`. This variable does not affect the
806 size of dynamic arrays, `xsd__hexBinary` and `xsd__base64Binary` types, which
807 is always `int`.
808 
809 🔝 [Back to table of contents](#)
810 
811 User-defined content {#typemap6}
812 --------------------
813 
814 Any other content to be generated by wsdl2h can be included in <i>`typemap.dat`</i> by
815 enclosing it within brackets <b>`[`</b> and <b>`]`</b> anywhere in the <i>`typemap.dat`</i> file.
816 Each of the two brackets must appear at the start of a new line.
817 
818 For example, we can add an `#import "wsa5.h"` to the wsdl2h-generated output as
819 follows:
820 
821  [
822  #import "import/wsa5.h"
823  ]
824 
825 which emits the `#import "import/wsa5.h"` literally at the start of the
826 wsdl2h-generated header file.
827 
828 🔝 [Back to table of contents](#)
829 
830 Mapping C/C++ to XML schema {#toxsd}
831 ===========================
832 
833 The soapcpp2 command generates the data binding implementation code from a data
834 binding interface <i>`file.h`</i>:
835 
836  soapcpp2 [options] file.h
837 
838 where <i>`file.h`</i> is a interface header file that declares the XML data
839 binding interface. The <i>`file.h`</i> is typically generated by wsdl2h, but
840 you can also declare one yourself. If so, add `//gsoap`
841 [directives](#directives) and declare in this file all our C/C++ types you want
842 to serialize in XML.
843 
844 You can also declare functions that will be converted to Web service operations
845 by soapcpp2. Global function declarations define service operations, which are
846 of the form:
847 
848 ~~~{.cpp}
849  int prefix__func(arg1, arg2, ..., argn, result);
850 ~~~
851 
852 where `arg1`, `arg2`, ..., `argn` are formal argument declarations of the input
853 and `result` is a formal argument for the output, which must be a pointer or
854 reference to the result object to be populated. More information on declaring
855 and implementing service operation functions can be found in the
856 [gSOAP user guide.](../../guide/html/index.html)
857 
858 🔝 [Back to table of contents](#)
859 
860 Overview of serializable C/C++ types {#toxsd1}
861 ------------------------------------
862 
863 The following C/C++ types are supported by soapcpp2 and mapped to XSD types
864 and constructs. See the subsections below for more details or follow the links.
865 
866 🔝 [Back to table of contents](#)
867 
868 ### List of Boolean types
869 
870 Boolean Type | Notes
871 ----------------------------- | -----
872 `bool` | C++ bool
873 `enum xsd__boolean` | C alternative to C++ `bool` with `false_` and `true_`
874 
875 @see Section [C++ bool and C alternative](#toxsd3).
876 
877 🔝 [Back to table of contents](#)
878 
879 ### List of enumeration and bitmask types
880 
881 Enumeration Type | Notes
882 ----------------------------- | -----
883 `enum` | enumeration
884 `enum class` | C++11 scoped enumeration, requires `soapcpp2 -c++11`
885 `enum*` | a bitmask that enumerates values 1, 2, 4, 8, ...
886 `enum* class` | C++11 scoped enumeration bitmask, requires `soapcpp2 -c++11`
887 
888 @see Section [enumerations and bitmasks](#toxsd4).
889 
890 🔝 [Back to table of contents](#)
891 
892 ### List of numerical types
893 
894 Numerical Type | Notes
895 ----------------------------- | -----
896 `char` | byte
897 `short` | 16 bit integer
898 `int` | 32 bit integer
899 `long` | 32 bit integer
900 `LONG64` | 64 bit integer
901 `xsd__integer` | 128 bit integer, use `#import "custom/int128.h"`
902 `long long` | same as `LONG64`
903 `unsigned char` | unsigned byte
904 `unsigned short` | unsigned 16 bit integer
905 `unsigned int` | unsigned 32 bit integer
906 `unsigned long` | unsigned 32 bit integer
907 `ULONG64` | unsigned 64 bit integer
908 `unsigned long long` | same as `ULONG64`
909 `int8_t` | same as `char`
910 `int16_t` | same as `short`
911 `int32_t` | same as `int`
912 `int64_t` | same as `LONG64`
913 `uint8_t` | same as `unsigned char`
914 `uint16_t` | same as `unsigned short`
915 `uint32_t` | same as `unsigned int`
916 `uint64_t` | same as `ULONG64`
917 `size_t` | transient type (not serializable)
918 `float` | 32 bit float
919 `double` | 64 bit float
920 `long double` | extended precision float, use `#import "custom/long_double.h"`
921 `xsd__decimal` | `quadmath.h` library 128 bit quadruple precision float, use `#import "custom/float128.h"`
922 `typedef` | declares a type name, with optional value range and string length bounds
923 
924 @see Section [numerical types](#toxsd5).
925 
926 🔝 [Back to table of contents](#)
927 
928 ### List of string types
929 
930 String Type | Notes
931 ----------------------------- | -----
932 `char*` | string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
933 `wchar_t*` | wide string
934 `std::string` | C++ string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
935 `std::wstring` | C++ wide string
936 `char[N]` | fixed-size string, requires `soapcpp2 -b`
937 `_QName` | normalized QName content
938 `_XML` | literal XML string content with wide characters in UTF-8
939 `typedef` | declares a new string type name, may restrict string length
940 
941 @see Section [string types](#toxsd6).
942 
943 🔝 [Back to table of contents](#)
944 
945 ### List of date and time types
946 
947 Date and Time Type | Notes
948 --------------------------------------- | -----
949 `time_t` | date and time point since epoch
950 `struct tm` | date and time point, use `#import "custom/struct_tm.h"`
951 `struct tm` | date point, use `#import "custom/struct_tm_date.h"`
952 `struct timeval` | date and time point, use `#import "custom/struct_timeval.h"`
953 `unsigned long long` | time point in microseconds, use `#import "custom/long_time.h"`
954 `std::chrono::system_clock::time_point` | date and time point, use `#import "custom/chrono_time_point.h"`
955 
956 @see Section [date and time types](#toxsd7).
957 
958 🔝 [Back to table of contents](#)
959 
960 ### List of time duration types
961 
962 Time Duration Type | Notes
963 ----------------------------- | -----
964 `long long` | duration in milliseconds, use `#import "custom/duration.h"`
965 `std::chrono::nanoseconds` | duration in nanoseconds, use `#import "custom/chrono_duration.h"`
966 
967 @see Section [time duration types](#toxsd8).
968 
969 🔝 [Back to table of contents](#)
970 
971 ### List of classes, structs, unions, pointers, containers, and arrays
972 
973 Classes, Structs, and Members | Notes
974 ----------------------------- | -----
975 `class` | C++ class with single inheritance only
976 `struct` | C struct or C++ struct without inheritance
977 `std::shared_ptr<T>` | C++11 smart shared pointer
978 `std::unique_ptr<T>` | C++11 smart pointer
979 `std::auto_ptr<T>` | C++ smart pointer
980 `std::deque<T>` | use `#import "import/stldeque.h"`
981 `std::list<T>` | use `#import "import/stllist.h"`
982 `std::vector<T>` | use `#import "import/stlvector.h"`
983 `std::set<T>` | use `#import "import/stlset.h"`
984 `template<T> class` | a container with `begin()`, `end()`, `size()`, `clear()`, and `insert()` methods
985 `T*` | pointer to data of type `T`
986 `T*` | as a class or struct member: points to data of type `T` or array of `T` with member `__size`
987 `T[N]` | as a class or struct member: fixed-size array of type `T`
988 `union` | as a class or struct member: requires a variant selector member `__union`
989 `void*` | as a class or struct member: requires a `__type` member to indicate the type of object pointed to
990 
991 @see Section [classes and structs](#toxsd9).
992 
993 🔝 [Back to table of contents](#)
994 
995 ### List of special classes and structs
996 
997 Special Classes and Structs | Notes
998 ----------------------------- | -----
999 Special Array class/struct | single and multidimensional SOAP Arrays
1000 Special Wrapper class/struct | complexTypes with simpleContent, wraps `__item` member
1001 `xsd__hexBinary` | binary content
1002 `xsd__base64Binary` | binary content and optional DIME/MIME/MTOM attachments
1003 `xsd__anyType` | DOM elements, use `#import "dom.h"`
1004 `@xsd__anyAttribute` | DOM attributes, use `#import "dom.h"`
1005 
1006 @see Section [special classes and structs](#toxsd10).
1007 
1008 🔝 [Back to table of contents](#)
1009 
1010 Colon notation versus name prefixing with XML tag name translation {#toxsd2}
1011 ------------------------------------------------------------------
1012 
1013 To bind C/C++ type names to XSD types, a simple form of name prefixing is used
1014 by the gSOAP tools by prepending the XML namespace prefix to the C/C++ type
1015 name with a pair of undescrores. This also ensures that name clashes cannot
1016 occur when multiple WSDL and XSD files are converted to C/C++. Also, C++
1017 namespaces are not sufficiently rich to capture XML schema namespaces
1018 accurately, for example when class members are associated with schema elements
1019 defined in another XML namespace and thus the XML namespace scope of the
1020 member's name is relevant, not just its type.
1021 
1022 However, from a C/C++ centric point of view this can be cumbersome. Therefore,
1023 colon notation is an alternative to physically augmenting C/C++ names with
1024 prefixes.
1025 
1026 For example, the following class uses colon notation to bind the `record` class
1027 to the <i>`urn:types`</i> schema:
1028 
1029 ~~~{.cpp}
1030  //gsoap ns schema namespace: urn:types
1031  class ns:record // binding 'ns:' to a type name
1032  { public:
1033  std::string name;
1034  uint64_t SSN;
1035  ns:record *spouse; // using 'ns:' with the type name
1036  ns:record(); // using 'ns:' here too
1037  ~ns:record(); // and here
1038  };
1039 ~~~
1040 
1041 The colon notation is stripped away by soapcpp2 when generating the data
1042 binding implementation code for our project. So the final code just uses
1043 `record` to identify this class and its constructor/destructor.
1044 
1045 When using colon notation make sure to be consistent and not use colon notation
1046 mixed with prefixed forms. The qualified name `ns:record` differs from `ns__record`,
1047 because `ns:record` is compiled to an unqualified `record` name in the source
1048 code output by the soapcpp2 tool.
1049 
1050 Colon notation also facilitates overruling the elementFormDefault and
1051 attributeFormDefault declaration that is applied to local elements and
1052 attributes, when declared as members of classes, structs, and unions. For more
1053 details, see [qualified and unqualified members](#toxsd9-6).
1054 
1055 A C/C++ identifier name (a type name, member name, function name, or parameter
1056 name) is translated to an XML tag name by the following rules:
1057 
1058 - Two leading underscores indicates that the identifier name has no XML tag
1059  name, i.e. this name is not visible in XML and is not translated.
1060 
1061 - A leading underscore is removed, but the underscore indicates that: **a**) a
1062  struct/class member name or parameter name has a wildcard XML tag name (i.e.
1063  matches any XML tag), or **b**) a type name that has a
1064  [document root element definition](#toxsd9-7).
1065 
1066 - Trailing underscores are removed (i.e. trailing underscores can be used to
1067  avoid name clashes with keywords).
1068 
1069 - Underscores within names are translated to hyphens (hyphens are more common
1070  in XML tag names).
1071 
1072 - `_USCORE` is translated to an underscore in the translated XML tag name.
1073 
1074 - `_DOT` is translated to a dot (<i>`.`</i>) in the translated XML tag name.
1075 
1076 - `_xHHHH` is translated to the Unicode character with code point HHHH (hex).
1077 
1078 - C++11 Unicode identifier name characters in UTF-8 are translated as-is.
1079 
1080 For example, the C/C++ namespace qualified identifier name `s_a__my_way` is
1081 translated to the XML tag name <i>`s-a:my-way`</i> by translating the prefix `s_a`
1082 and the local name `my_way`.
1083 
1084 Struct/class member and parameter name translation can be overruled by using
1085 [backtick XML tags](#toxsd9-5-1) (with gSOAP 2.8.30 and greater).
1086 
1087 🔝 [Back to table of contents](#)
1088 
1089 C++ bool and C alternative {#toxsd3}
1090 --------------------------
1091 
1092 The C++ `bool` type is bound to built-in XSD type <i>`xsd:boolean`</i>.
1093 
1094 The C alternative is to define an enumeration:
1095 
1096 ~~~{.cpp}
1097  enum xsd__boolean { false_, true_ };
1098 ~~~
1099 
1100 or by defining an enumeration in C with pseudo-scoped enumeration constants:
1101 
1102 ~~~{.cpp}
1103  enum xsd__boolean { xsd__boolean__false, xsd__boolean__true };
1104 ~~~
1105 
1106 The XML value space of these types is <i>`false`</i> and <i>`true`</i>, but also accepted
1107 are <i>`0`</i> and <i>`1`</i> values for <i>`false`</i> and <i>`true`</i>, respectively.
1108 
1109 To prevent name clashes, `false_` and `true_` have a trailing underscore in
1110 their `enum` symbols. Trailing underscores are removed from the XML value space.
1111 
1112 🔝 [Back to table of contents](#)
1113 
1114 Enumerations and bitmasks {#toxsd4}
1115 -------------------------
1116 
1117 Enumerations are mapped to XSD simpleType enumeration restrictions of
1118 <i>`xsd:string`</i>, <i>`xsd:QName`</i>, and <i>`xsd:long`</i>.
1119 
1120 Consider for example:
1121 
1122 ~~~{.cpp}
1123  enum ns__Color { RED, WHITE, BLUE };
1124 ~~~
1125 
1126 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1127 schema:
1128 
1129 <div class="alt">
1130 ~~~{.xml}
1131  <simpleType name="Color">
1132  <restriction base="xsd:string">
1133  <enumeration value="RED"/>
1134  <enumeration value="WHITE"/>
1135  <enumeration value="BLUE"/>
1136  </restriction>
1137  </simpleType>
1138 ~~~
1139 </div>
1140 
1141 Enumeration name constants can be pseudo-scoped to prevent name clashes,
1142 because enumeration name constants have a global scope in C and C++:
1143 
1144 ~~~{.cpp}
1145  enum ns__Color { ns__Color__RED, ns__Color__WHITE, ns__Color__BLUE };
1146 ~~~
1147 
1148 You can also use C++11 scoped enumerations to prevent name clashes:
1149 
1150 ~~~{.cpp}
1151  enum class ns__Color : int { RED, WHITE, BLUE };
1152 ~~~
1153 
1154 Here, the enumeration class base type `: int` is optional. In place of `int`
1155 in the example above, we can also use `int8_t`, `int16_t`, `int32_t`, or
1156 `int64_t`.
1157 
1158 The XML value space of the enumertions defined above is <i>`RED`</i>, <i>`WHITE`</i>, and
1159 <i>`BLUE`</i>.
1160 
1161 Prefix-qualified enumeration name constants are mapped to simpleType
1162 restrictions of <i>`xsd:QName`</i>, for example:
1163 
1164 ~~~{.cpp}
1165  enum ns__types { xsd__int, xsd__float };
1166 ~~~
1167 
1168 which maps to a simpleType restriction of <i>`xsd:QName`</i> in the soapcpp2-generated
1169 schema:
1170 
1171 <div class="alt">
1172 ~~~{.xml}
1173  <simpleType name="types">
1174  <restriction base="xsd:QName">
1175  <enumeration value="xsd:int"/>
1176  <enumeration value="xsd:float"/>
1177  </restriction>
1178  </simpleType>
1179 ~~~
1180 </div>
1181 
1182 Enumeration name constants can be pseudo-numeric as follows:
1183 
1184 ~~~{.cpp}
1185  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1186 ~~~
1187 
1188 which maps to a simpleType restriction of <i>`xsd:long`</i>:
1189 
1190 <div class="alt">
1191 ~~~{.xml}
1192  <simpleType name="Color">
1193  <restriction base="xsd:long">
1194  <enumeration value="3"/>
1195  <enumeration value="5"/>
1196  <enumeration value="7"/>
1197  <enumeration value="11"/>
1198  </restriction>
1199  </simpleType>
1200 ~~~
1201 </div>
1202 
1203 The XML value space of this type is <i>`3`</i>, <i>`5`</i>, <i>`7`</i>, and <i>`11`</i>.
1204 
1205 Besides (pseudo-) scoped enumerations, another way to prevent name clashes
1206 accross enumerations is to start an enumeration name constant with one
1207 underscore or followed it by any number of underscores, which makes it
1208 unique. The leading and trailing underscores are removed from the XML value
1209 space.
1210 
1211 ~~~{.cpp}
1212  enum ns__ABC { A, B, C };
1213  enum ns__BA { B, A }; // BAD: B = 1 but B is already defined as 2
1214  enum ns__BA_ { B_, A_ }; // OK
1215 ~~~
1216 
1217 The gSOAP soapcpp2 tool permits reusing enumeration name constants across
1218 (non-scoped) enumerations as long as these values are assigned the same
1219 constant. Therefore, the following is permitted:
1220 
1221 ~~~{.cpp}
1222  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1223  enum ns__Throws { _1 = 1, _2 = 2, _3 = 3, _4 = 4, _5 = 5, _6 = 6 };
1224 ~~~
1225 
1226 A bitmask type is an `enum*` "product enumeration" with a geometric,
1227 power-of-two sequence of values assigned to the enumeration constants:
1228 
1229 ~~~{.cpp}
1230  enum* ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1231 ~~~
1232 
1233 where the product enum assigns 1 to `SSL3`, 2 to `TLS10`, 4 to `TLS11`, 8
1234 to `TLS12`, and 16 to `TLS13`, which allows these enumeration constants to be
1235 used in composing bitmasks with `|` (bitwise or) `&` (bitwise and), and `~`
1236 (bitwise not):
1237 
1238 ~~~{.cpp}
1239  enum ns__Options options = (enum ns__Options)(SSL3 | TLS10 | TLS11 | TLS12 | TLS13);
1240  if (options & SSL3) // if SSL3 is an option, warn and remove from options
1241  {
1242  warning();
1243  options &= ~SSL3;
1244  }
1245 ~~~
1246 
1247 The bitmask type maps to a simpleType list restriction of <i>`xsd:string`</i> in the
1248 soapcpp2-generated XML schema:
1249 
1250 <div class="alt">
1251 ~~~{.xml}
1252  <simpleType name="Options">
1253  <list>
1254  <restriction base="xsd:string">
1255  <enumeration value="SSL3"/>
1256  <enumeration value="TLS10"/>
1257  <enumeration value="TLS11"/>
1258  <enumeration value="TLS12"/>
1259  <enumeration value="TLS13"/>
1260  </restriction>
1261  </list>
1262  </simpleType>
1263 ~~~
1264 </div>
1265 
1266 The XML value space of this type consists of all 16 possible subsets of the
1267 four values, represented by an XML string with space-separated values. For
1268 example, the bitmask `TLS10 | TLS11 | TLS12` equals 14 and is represented by
1269 the XML text <i>`TLS10 TLS11 TLS12`</i>.
1270 
1271 You can also use C++11 scoped enumerations with bitmasks using `enum*` product
1272 enumerations:
1273 
1274 ~~~{.cpp}
1275  enum* class ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1276 ~~~
1277 
1278 The base type of a scoped enumeration bitmask, when explicitly given, is
1279 ignored. The base type is either `int` or `int64_t`, depending on the number
1280 of constants enumerated in the bitmask.
1281 
1282 To convert `enum` name constants and bitmasks to a string, we use the
1283 auto-generated function for enum `T`:
1284 
1285 ~~~{.cpp}
1286  const char *soap_T2s(struct soap*, enum T val)
1287 ~~~
1288 
1289 The string returned is stored in an internal buffer of the current `soap`
1290 context, so you should copy it to keep it from being overwritten. For example,
1291 use `char *soap_strdup(struct soap*, const char*)`.
1292 
1293 To convert a string to an `enum` constant or bitmask, we use the auto-generated
1294 function
1295 
1296 ~~~{.cpp}
1297  int soap_s2T(struct soap*, const char *str, enum T *val)
1298 ~~~
1299 
1300 This function takes the name (or names, space-separated for bitmasks) of
1301 the enumeration constant in a string `str`. Names should be given without the
1302 pseudo-scope prefix and without trailing underscores. The function sets `val`
1303 to the corresponding integer enum constant or to a bitmask. The function
1304 returns `SOAP_OK` (zero) on success or an error if the string is not a valid
1305 enumeration name.
1306 
1307 🔝 [Back to table of contents](#)
1308 
1309 Numerical types {#toxsd5}
1310 ---------------
1311 
1312 Integer and floating point types are mapped to the equivalent built-in XSD
1313 types with the same sign and bit width.
1314 
1315 The `size_t` type is transient (not serializable) because its width is platform
1316 dependent. We recommend to use `uint64_t` instead.
1317 
1318 The XML value space of integer types are their decimal representations without
1319 loss of precision.
1320 
1321 The XML value space of floating point types are their decimal representations.
1322 The decimal representations are formatted with the printf format string `"%.9G"`
1323 for floats and the printf format string `"%.17lG"` for double. To change the
1324 format strings, we can assign new strings to the following `soap` context
1325 members:
1326 
1327 ~~~{.cpp}
1328  soap.float_format = "%g";
1329  soap.double_format = "%lg";
1330  soap.long_double_format = "%Lg";
1331 ~~~
1332 
1333 Decimal representations may result in a loss of precision of the least
1334 significant decimal. Therefore, the format strings that are used by default
1335 are sufficiently precise to avoid loss, but this may result in long decimal
1336 fractions in the XML value space.
1337 
1338 The `long double` extended floating point type requires a custom serializer:
1339 
1340 ~~~{.cpp}
1341  #import "custom/long_double.h"
1342  ... // use long double
1343 ~~~
1344 
1345 You can now use `long double`, which has a serializer that serializes this type
1346 as <i>`xsd:decimal`</i>. Compile and link your code with the file
1347 <i>`gsoap/custom/long_double.c`</i>.
1348 
1349 The value space of floating point values includes the special values
1350 <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i>. You can check a value for plus
1351 or minus infinity and not-a-number as follows:
1352 
1353 ~~~{.cpp}
1354  soap_isinf(x) && x > 0 // is x INF?
1355  soap_isinf(x) && x < 0 // is x -INF?
1356  soap_isnan(x) // is x NaN?
1357 ~~~
1358 
1359 To assign these values, use:
1360 
1361 ~~~{.cpp}
1362  // x is float // x is double, long double, or __float128
1363  x = FLT_PINFY; x = DBL_PINFTY;
1364  x = FLT_NINFY; x = DBL_NINFTY;
1365  x = FLT_NAN; x = DBL_NAN;
1366 ~~~
1367 
1368 If your system supports `__float128` then you can also use this 128 bit
1369 floating point type with a custom serializer:
1370 
1371 ~~~{.cpp}
1372  #import "custom/float128.h"
1373  ... // use xsd__decimal
1374 ~~~
1375 
1376 Then use the `xsd__decimal` alias of `__float128`, which has a serializer. Do
1377 not use `__float128` directly, which is transient (not serializable).
1378 
1379 To check for <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i> of a `__float128`
1380 value use:
1381 
1382 ~~~{.cpp}
1383  isinfq(x) && x > 0 // is x INF?
1384  isinfq(x) && x < 0 // is x -INF?
1385  isnanq(x) // is x NaN?
1386 ~~~
1387 
1388 The range of a `typedef`-defined numerical type can be restricted using the range
1389 `:` operator with inclusive lower and upper bounds. For example:
1390 
1391 ~~~{.cpp}
1392  typedef int ns__narrow -10 : 10;
1393 ~~~
1394 
1395 This maps to a simpleType restriction of <i>`xsd:int`</i> in the soapcpp2-generated
1396 schema:
1397 
1398 <div class="alt">
1399 ~~~{.xml}
1400  <simpleType name="narrow">
1401  <restriction base="xsd:int">
1402  <minInclusive value="-10"/>
1403  <maxInclusive value="10"/>
1404  </restriction>
1405  </simpleType>
1406 ~~~
1407 </div>
1408 
1409 The lower and upper bound of a range are optional. When omitted, values are
1410 not bound from below or from above, respectively.
1411 
1412 The range of a floating point `typedef`-defined type can be restricted within
1413 floating point constant bounds.
1414 
1415 Also with a floating point `typedef` a `printf`-format pattern can be given of the
1416 form `"%[width][.precision]f"` to format decimal values using the given width
1417 and precision fields:
1418 
1419 ~~~{.cpp}
1420  typedef float ns__PH "%5.2f" 0.0 : 14.0;
1421 ~~~
1422 
1423 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1424 schema:
1425 
1426 <div class="alt">
1427 ~~~{.xml}
1428  <simpleType name="PH">
1429  <restriction base="xsd:float">
1430  <totalDigits value="5"/>
1431  <fractionDigits value="2"/>
1432  <minInclusive value="0"/>
1433  <maxInclusive value="14"/>
1434  </restriction>
1435  </simpleType>
1436 ~~~
1437 </div>
1438 
1439 For exclusive bounds, we use the `<` operator instead of the `:` range
1440 operator:
1441 
1442 ~~~{.cpp}
1443  typedef float ns__epsilon 0.0 < 1.0;
1444 ~~~
1445 
1446 Values `eps` of `ns__epsilon` are restricted between `0.0 < eps < 1.0`.
1447 
1448 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1449 schema:
1450 
1451 <div class="alt">
1452 ~~~{.xml}
1453  <simpleType name="epsilon">
1454  <restriction base="xsd:float">
1455  <minExclusive value="0"/>
1456  <maxExclusive value="1"/>
1457  </restriction>
1458  </simpleType>
1459 ~~~
1460 </div>
1461 
1462 To make just one of the bounds exclusive, while keeping the other bound
1463 inclusive, we add a `<` on the left or on the right side of the range ':'
1464 operator. For example:
1465 
1466 ~~~{.cpp}
1467  typedef float ns__pos 0.0 < : ; // 0.0 < pos
1468  typedef float ns__neg : < 0.0 ; // neg < 0.0
1469 ~~~
1470 
1471 It is valid to make both left and right side exclusive with `< : <` which is in
1472 fact identical to the exlusive range `<` operator:
1473 
1474 ~~~{.cpp}
1475  typedef float ns__epsilon 0.0 < : < 1.0; // 0.0 < eps < 1.0
1476 ~~~
1477 
1478 It helps to think of the `:` as a placeholder of the value between the two
1479 bounds, which is easier to memorize than the shorthand forms of bounds from
1480 which the `:` is removed:
1481 
1482 | bounds | validation check | shorthand |
1483 | ------------ | ---------------- | ----------- |
1484 | `1 : ` | 1 <= x | `1 ` |
1485 | `1 : 10 ` | 1 <= x <= 10 | |
1486 | ` : 10 ` | x <= 10 | |
1487 | `1 < : < 10` | 1 < x < 10 | `1 < 10 ` |
1488 | `1 : < 10` | 1 <= x < 10 | |
1489 | ` : < 10` | x < 10 | ` < 10 ` |
1490 | `1 < : ` | 1 < x | `1 < ` |
1491 | `1 < : 10 ` | 1 < x <= 10 | |
1492 
1493 Besides `float`, also `double` and `long double` values can be restricted. For
1494 example, consider a nonzero probability extended floating point precision type:
1495 
1496 ~~~{.cpp}
1497  #import "custom/long_double.h"
1498  typedef long double ns__probability "%16Lg" 0.0 < : 1.0;
1499 ~~~
1500 
1501 Value range restrictions are validated by the parser for all inbound XML data.
1502 A type fault `SOAP_TYPE` will be thrown by the deserializer if the value is out
1503 of range.
1504 
1505 Finally, if your system supports `__int128_t` then you can also use this 128
1506 bit integer type with a custom serializer:
1507 
1508 ~~~{.cpp}
1509  #import "custom/int128.h"
1510  ... // use xsd__integer
1511 ~~~
1512 
1513 Use the `xsd__integer` alias of `__int128_t`, which has a serializer. Do not
1514 use `__int128_t` directly, which is transient (not serializable).
1515 
1516 To convert numeric values to a string, we use the auto-generated function for
1517 numeric type `T`:
1518 
1519 ~~~{.cpp}
1520  const char *soap_T2s(struct soap*, T val)
1521 ~~~
1522 
1523 For numeric types `T`, the string returned is stored in an internal buffer of
1524 the current `soap` context, so you should copy it to keep it from being
1525 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1526 
1527 To convert a string to a numeric value, we use the auto-generated function
1528 
1529 ~~~{.cpp}
1530  int soap_s2T(struct soap*, const char *str, T *val)
1531 ~~~
1532 
1533 where `T` is for example `int`, `LONG64`, `float`, `decimal` (the custom
1534 serializer name of `long double`) or `xsd__integer` (the custom serializer name
1535 of `__int128_t`). The function `soap_s2T` returns `SOAP_OK` on success or an
1536 error when the value is not numeric. For floating point types, `"INF"`, `"-INF"`
1537 and `"NaN"` are valid strings to convert to numbers.
1538 
1539 🔝 [Back to table of contents](#)
1540 
1541 String types {#toxsd6}
1542 ------------
1543 
1544 String types are mapped to the built-in <i>`xsd:string`</i> and <i>`xsd:QName`</i> XSD types.
1545 
1546 The wide strings `wchar_t*` and `std::wstring` may contain Unicode that is
1547 preserved in the XML value space.
1548 
1549 Strings `char*` and `std::string` can only contain extended Latin, but we can
1550 store UTF-8 content that is preserved in the XML value space when the `soap`
1551 context is initialized with the flag `SOAP_C_UTFSTRING`.
1552 
1553 @warning Beware that many XML 1.0 parsers reject all control characters (those
1554 between `#x1` and `#x1F`) except for `#x9`, `#xA`, and `#xD`. With the
1555 newer XML 1.1 version parsers (including gSOAP) you should be fine.
1556 
1557 The length of a string of a `typedef`-defined string type can be restricted:
1558 
1559 ~~~{.cpp}
1560  typedef std::string ns__password 6 : 16;
1561 ~~~
1562 
1563 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1564 schema:
1565 
1566 <div class="alt">
1567 ~~~{.xml}
1568  <simpleType name="password">
1569  <restriction base="xsd:string">
1570  <minLength value="6"/>
1571  <maxLength value="16"/>
1572  </restriction>
1573  </simpleType>
1574 ~~~
1575 </div>
1576 
1577 String length restrictions are validated by the parser for inbound XML data.
1578 A value length fault `SOAP_LENGTH` will be thrown by the deserializer if the
1579 string is too long or too short.
1580 
1581 In addition, an XSD regex pattern restriction can be associated with a string
1582 typedef:
1583 
1584 ~~~{.cpp}
1585  typedef std::string ns__password "([a-zA-Z]|[0-9]|-)+" 6 : 16;
1586 ~~~
1587 
1588 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1589 schema:
1590 
1591 <div class="alt">
1592 ~~~{.xml}
1593  <simpleType name="password">
1594  <restriction base="xsd:string">
1595  <pattern value="([a-zA-Z0-9]|-)+"/>
1596  <minLength value="6"/>
1597  <maxLength value="16"/>
1598  </restriction>
1599  </simpleType>
1600 ~~~
1601 </div>
1602 
1603 Pattern restrictions are validated by the parser for inbound XML data only if
1604 the `soap::fsvalidate` and `soap::fwvalidate` callbacks are defined.
1605 
1606 Exclusive length bounds can be used with strings:
1607 
1608 ~~~{.cpp}
1609  typedef std::string ns__string255 : < 256; // same as 0 : 255
1610 ~~~
1611 
1612 Fixed-size strings (`char[N]`) are rare occurrences in the wild, but apparently
1613 still used in some projects to store strings. To facilitate fixed-size string
1614 serialization, use <b>`soapcpp2 -b`</b> option <b>`-b`</b>. For example:
1615 
1616 ~~~{.cpp}
1617  typedef char ns__buffer[10]; // requires soapcpp2 option -b
1618 ~~~
1619 
1620 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1621 schema:
1622 
1623 <div class="alt">
1624 ~~~{.xml}
1625  <simpleType name="buffer">
1626  <restriction base="xsd:string">
1627  <maxLength value="9"/>
1628  </restriction>
1629  </simpleType>
1630 ~~~
1631 </div>
1632 
1633 Fixed-size strings must contain NUL-terminated text and should not contain raw
1634 binary data. Also, the length limitation is more restrictive for UTF-8 content
1635 (enabled with the `SOAP_C_UTFSTRING`) that requires multibyte character
1636 encodings. As a consequence, UTF-8 content may be truncated to fit.
1637 
1638 Raw binary data can be stored in a `xsd__base64Binary` or `xsd__hexBinary`
1639 structure, or transmitted as a MIME attachment.
1640 
1641 The built-in `_QName` type is a regular C string type (`char*`) that maps to
1642 <i>`xsd:QName`</i> but has the added advantage that it holds normalized qualified names.
1643 There are actually two forms of normalized QName content, to ensure any QName
1644 is represented accurately:
1645 
1646 ~~~{.cpp}
1647  "prefix:name"
1648  "\"URI\":name"
1649 ~~~
1650 
1651 The first form of string is used when the prefix (and the binding URI) is
1652 defined in the namespace table and is bound to a URI (see the .nsmap file).
1653 The second form is used when the URI is not defined in the namespace table and
1654 therefore no prefix is available to bind and normalize the URI to.
1655 
1656 A `_QName` string may contain a sequence of space-separated QName values, not
1657 just one, and all QName values are normalized to the format shown above.
1658 
1659 To define a `std::string` base type for <i>`xsd:QName`</i>, we use a `typedef`:
1660 
1661 ~~~{.cpp}
1662  typedef std::string xsd__QName;
1663 ~~~
1664 
1665 The `xsd__QName` string content is normalized, just as with the `_QName`
1666 normalization.
1667 
1668 To serialize strings that contain literal XML content to be reproduced in the
1669 XML value space, use the built-in `_XML` string type, which is a regular C
1670 string type (`char*`) that maps to plain XML CDATA.
1671 
1672 To define a `std::string` base type for literal XML content, use a `typedef`:
1673 
1674 ~~~{.cpp}
1675  typedef std::string XML;
1676 ~~~
1677 
1678 Strings can hold any of the values of the XSD built-in primitive types. We can
1679 use a string `typedef` to declare the use of the string type as a XSD built-in
1680 type:
1681 
1682 ~~~{.cpp}
1683  typedef std::string xsd__token;
1684 ~~~
1685 
1686 You must ensure that the string values we populate in this type conform to the
1687 XML standard, which in case of <i>`xsd:token`</i> is the lexical and value spaces of
1688 <i>`xsd:token`</i> are the sets of all strings after whitespace replacement of any
1689 occurrence of `#x9`, `#xA` , and `#xD` by `#x20` and collapsing.
1690 
1691 As of version 2.8.49, the gSOAP parser will automatically collapse or replace
1692 the white space content when receiving data for XSD types that require white
1693 space collapsed or replaced. This normalization is applied to strings
1694 directly. The decision to collapse or replace is based on the `typedef` name
1695 corresponding to the built-in string-based XSD type.
1696 
1697 To copy `char*` or `wchar_t*` strings with a context that manages the allocated
1698 memory, use functions
1699 
1700 ~~~{.cpp}
1701  char *soap_strdup(struct soap*, const char*)
1702  wchar_t *soap_wstrdup(struct soap*, const wchar_t*)
1703 ~~~
1704 
1705 To convert a wide string to a UTF-8 encoded string, use function
1706 
1707 ~~~{.cpp}
1708  const char* SOAP_FMAC2 soap_wchar2s(struct soap*, const wchar_t *s)
1709 ~~~
1710 
1711 The function allocates and returns a string, with its memory being managed by
1712 the context.
1713 
1714 To convert a UTF-8 encoded string to a wide string, use function
1715 
1716 ~~~{.cpp}
1717  int soap_s2wchar(struct soap*, const char *from, wchar_t **to, long minlen, long maxlen)
1718 ~~~
1719 
1720 where `to` is set to point to an allocated `wchar_t*` string. Pass `-1` for
1721 `minlen` and `maxlen` to ignore length constraints on the target string. The
1722 function returns `SOAP_OK` or an error when the length constraints are not met.
1723 
1724 🔝 [Back to table of contents](#)
1725 
1726 Date and time types {#toxsd7}
1727 -------------------
1728 
1729 The C/C++ `time_t` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type that
1730 represents a date and time within a time zone (typically UTC).
1731 
1732 The XML value space contains ISO 8601 Gregorian time instances of the form
1733 <i>`[-]CCYY-MM-DDThh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone
1734 or a time zone offset <i>`(+|-)hh:mm]`</i> from UTC is used.
1735 
1736 A `time_t` value is considered and represented in UTC by the serializer.
1737 
1738 Because the `time_t` value range is restricted to dates after 01/01/1970 and
1739 before 2038 assuming `time_t` is a `long` 32 bit, care must be taken to ensure
1740 the range of <i>`xsd:dateTime`</i> values in XML exchanges do not exceed the `time_t`
1741 range.
1742 
1743 This restriction does not hold for `struct tm` (<i>`time.h`</i> library), which we can use
1744 to store and exchange a date and time in UTC without date range restrictions.
1745 The serializer uses the `struct tm` members directly for the XML value space of
1746 <i>`xsd:dateTime`</i>:
1747 
1748 ~~~{.cpp}
1749  struct tm
1750  {
1751  int tm_sec; // seconds (0 - 60)
1752  int tm_min; // minutes (0 - 59)
1753  int tm_hour; // hours (0 - 23)
1754  int tm_mday; // day of month (1 - 31)
1755  int tm_mon; // month of year (0 - 11)
1756  int tm_year; // year - 1900
1757  int tm_wday; // day of week (Sunday = 0) (NOT USED)
1758  int tm_yday; // day of year (0 - 365) (NOT USED)
1759  int tm_isdst; // is summer time in effect?
1760  char* tm_zone; // abbreviation of timezone (NOT USED)
1761  };
1762 ~~~
1763 
1764 You will lose the day of the week information. It is always Sunday
1765 (`tm_wday=0`) and the day of the year is not set either. The time zone is UTC.
1766 
1767 This `struct tm` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type and
1768 serialized with the custom serializer <i>`gsoap/custom/struct_tm.h`</i> that declares a
1769 `xsd__dateTime` type:
1770 
1771 ~~~{.cpp}
1772  #import "custom/struct_tm.h" // import typedef struct tm xsd__dateTime;
1773  ... // use xsd__dateTime
1774 ~~~
1775 
1776 Compile and link your code with <i>`gsoap/custom/struct_tm.c`</i>.
1777 
1778 The `struct timeval` (<i>`sys/time.h`</i> library) type is mapped to the
1779 built-in <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1780 <i>`gsoap/custom/struct_timeval.h`</i> that declares a `xsd__dateTime` type:
1781 
1782 ~~~{.cpp}
1783  #import "custom/struct_timeval.h" // import typedef struct timeval xsd__dateTime;
1784  ... // use xsd__dateTime
1785 ~~~
1786 
1787 Compile and link your code with <i>`gsoap/custom/struct_timeval.c`</i>.
1788 
1789 The same value range restrictions apply to `struct timeval` as they apply to
1790 `time_t`. The added benefit of `struct timeval` is the addition of a
1791 microsecond-precise clock:
1792 
1793 ~~~{.cpp}
1794  struct timeval
1795  {
1796  time_t tv_sec; // seconds since Jan. 1, 1970
1797  suseconds_t tv_usec; // and microseconds
1798  };
1799 ~~~
1800 
1801 A C++11 `std::chrono::system_clock::time_point` type is mapped to the built-in
1802 <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1803 <i>`gsoap/custom/chrono_time_point.h`</i> that declares a `xsd__dateTime` type:
1804 
1805 ~~~{.cpp}
1806  #import "custom/chrono_time_point.h" // import typedef std::chrono::system_clock::time_point xsd__dateTime;
1807  ... // use xsd__dateTime
1808 ~~~
1809 
1810 Compile and link your code with <i>`gsoap/custom/chrono_time_point.cpp`</i>.
1811 
1812 The `struct tm` type is mapped to the built-in <i>`xsd:date`</i> XSD type and serialized
1813 with the custom serializer <i>`gsoap/custom/struct_tm_date.h`</i> that declares a
1814 `xsd__date` type:
1815 
1816 ~~~{.cpp}
1817  #import "custom/struct_tm_date.h" // import typedef struct tm xsd__date;
1818  ... // use xsd__date
1819 ~~~
1820 
1821 Compile and link your code with <i>`gsoap/custom/struct_tm_date.c`</i>.
1822 
1823 The XML value space of <i>`xsd:date`</i> are Gregorian calendar dates of the form
1824 <i>`[-]CCYY-MM-DD[Z|(+|-)hh:mm]`</i> with a time zone.
1825 
1826 The serializer ignores the time part and the deserializer only populates the
1827 date part of the struct, setting the time to 00:00:00. There is no unreasonable
1828 limit on the date range because the year field is stored as an integer (`int`).
1829 
1830 An `unsigned long long` (`ULONG64` or `uint64_t`) type that contains a 24 hour
1831 time in microseconds UTC is mapped to the built-in <i>`xsd:time`</i> XSD type and
1832 serialized with the custom serializer <i>`gsoap/custom/long_time.h`</i> that declares a
1833 `xsd__time` type:
1834 
1835 ~~~{.cpp}
1836  #import "custom/long_time.h" // import typedef unsigned long long xsd__time;
1837  ... // use xsd__time
1838 ~~~
1839 
1840 Compile and link your code with <i>`gsoap/custom/long_time.c`</i>.
1841 
1842 This type represents `00:00:00.000000` to `23:59:59.999999`, from 0 to an
1843 upper bound of 86,399,999,999. A microsecond resolution means that a 1 second
1844 increment requires an increment of 1,000,000 in the integer value.
1845 
1846 The XML value space of <i>`xsd:time`</i> are points in time recurring each day of the
1847 form <i>`hh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone or a time
1848 zone offset from UTC is used. The `xsd__time` value is always considered and
1849 represented in UTC by the serializer.
1850 
1851 To convert date and/or time values to a string, we use the auto-generated
1852 function for type `T`:
1853 
1854 ~~~{.cpp}
1855  const char *soap_T2s(struct soap*, T val)
1856 ~~~
1857 
1858 For date and time types `T`, the string returned is stored in an internal
1859 buffer of the current `soap` context, so you should copy it to keep it from being
1860 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1861 
1862 To convert a string to a date/time value, we use the auto-generated function
1863 
1864 ~~~{.cpp}
1865  int soap_s2T(struct soap*, const char *str, T *val)
1866 ~~~
1867 
1868 where `T` is for example `dateTime` (for `time_t`), `xsd__dateTime` (for
1869 `struct tm`, `struct timeval`, or `std::chrono::system_clock::time_point`).
1870 The function `soap_s2T` returns `SOAP_OK` on success or an error when the value
1871 is not a date/time.
1872 
1873 🔝 [Back to table of contents](#)
1874 
1875 Time duration types {#toxsd8}
1876 -------------------
1877 
1878 The XML value space of <i>`xsd:duration`</i> are values of the form <i>`PnYnMnDTnHnMnS`</i>
1879 where the capital letters are delimiters. Delimiters may be omitted when the
1880 corresponding member is not used.
1881 
1882 A `long long` (`LONG64` or `int64_t`) type that contains a duration (time
1883 lapse) in milliseconds is mapped to the built-in <i>`xsd:duration`</i> XSD type and
1884 serialized with the custom serializer <i>`gsoap/custom/duration.h`</i> that declares a
1885 `xsd__duration` type:
1886 
1887 ~~~{.cpp}
1888  #import "custom/duration.h" // import typedef long long xsd__duration;
1889  ... // use xsd__duration
1890 ~~~
1891 
1892 Compile and link your code with <i>`gsoap/custom/duration.c`</i>.
1893 
1894 The duration type `xsd__duration` can represent 106,751,991,167 days forward
1895 and backward with millisecond precision.
1896 
1897 Durations that exceed a month are always output in days, rather than months to
1898 avoid days-per-month conversion inacurracies.
1899 
1900 Durations that are received in years and months instead of total number of days
1901 from a reference point are not well defined, since there is no accepted
1902 reference time point (it may or may not be the current time). The decoder
1903 simple assumes that there are 30 days per month. For example, conversion of
1904 "P4M" gives 120 days. Therefore, the durations "P4M" and "P120D" are assumed
1905 to be identical, which is not necessarily true depending on the reference point
1906 in time.
1907 
1908 Rescaling of the duration value by may be needed when adding the duration value
1909 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
1910 depending on the platform and possible changes to `time_t`.
1911 
1912 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
1913 value to a `std::chrono::system_clock::time_point` value. To use
1914 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
1915 
1916 ~~~{.cpp}
1917  #import "custom/chrono_duration.h" // import typedef std::chrono::duration xsd__duration;
1918  ... // use xsd__duration
1919 ~~~
1920 
1921 Compile and link your code with <i>`gsoap/custom/chrono_duration.cpp`</i>.
1922 
1923 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
1924 backwards in time in increments of 1 ns (1/1000000000 second).
1925 
1926 The same observations with respect to receiving durations in years and months
1927 apply to this serializer's decoder.
1928 
1929 To convert duration values to a string, we use the auto-generated function
1930 
1931 ~~~{.cpp}
1932  const char *soap_xsd__duration2s(struct soap*, xsd__duration val)
1933 ~~~
1934 
1935 The string returned is stored in an internal buffer, so you should copy it to
1936 keep it from being overwritten, Use `soap_strdup(struct soap*, const char*)`
1937 for example to copy this string.
1938 
1939 To convert a string to a duration value, we use the auto-generated function
1940 
1941 ~~~{.cpp}
1942  int soap_s2xsd__dateTime(struct soap*, const char *str, xsd__dateTime *val)
1943 ~~~
1944 
1945 The function returns `SOAP_OK` on success or an error when the value is not a
1946 duration.
1947 
1948 🔝 [Back to table of contents](#)
1949 
1950 Classes and structs {#toxsd9}
1951 -------------------
1952 
1953 Classes and structs are mapped to XSD complexTypes. The XML value space
1954 consists of XML elements with attributes and subelements, possibly constrained
1955 by XML schema validation rules that enforce element and attribute occurrence
1956 contraints, numerical value range constraints, and string length and pattern
1957 constraints.
1958 
1959 Classes that are declared with the gSOAP tools are limited to single
1960 inheritence only. The soapcpp2 tool does not allow structs to be inherited.
1961 
1962 The class and struct name is bound to an XML namespace by means of the prefix
1963 naming convention or by using [colon notation](#toxsd1):
1964 
1965 ~~~{.cpp}
1966  //gsoap ns schema namespace: urn:types
1967  class ns__record
1968  { public:
1969  std::string name;
1970  uint64_t SSN;
1971  ns__record *spouse;
1972  ns__record();
1973  ~ns__record();
1974  protected:
1975  struct soap *soap;
1976  };
1977 ~~~
1978 
1979 In the example above, we also added a context pointer to the `soap` context that
1980 manages this instance. It is set when the instance is created in the engine's
1981 context, for example when deserialized and populated by the engine.
1982 
1983 The class maps to a complexType in the soapcpp2-generated XML schema:
1984 
1985 <div class="alt">
1986 ~~~{.xml}
1987  <complexType name="record">
1988  <sequence>
1989  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
1990  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
1991  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1992  </sequence>
1993  </complexType>
1994 ~~~
1995 </div>
1996 
1997 The following sections apply to both structs and classes. Structs require the
1998 use of the `struct` keyword with the struct name, otherwise soapcpp2 will throw
1999 a syntax error. As is often done in C, use a `typedef` to declare a `struct`
2000 that can be used without the `struct` keyword.
2001 
2002 🔝 [Back to table of contents](#)
2003 
2004 ### Serializable versus transient types and data members {#toxsd9-1}
2005 
2006 Public data members of a class or struct are serializable when their types are
2007 serializable. Private and protected members are transient and not
2008 serializable.
2009 
2010 Also `const` and `static` members are not serializable, with the exception of
2011 `const char*` and `const wchar_t*`. Types and specific class/struct members
2012 can be made transient with the `extern` qualifier for types and by marking
2013 members with `[` and `]`:
2014 
2015 ~~~{.cpp}
2016  extern class std::ostream; // declare std::ostream transient
2017  class ns__record
2018  { public:
2019  [ int num; ] // not serialized: member is marked transient with [ ]
2020  std::ostream out; // not serialized: std:ostream is transient
2021  static const int MAX = 1024; // not serialized: static const member
2022  private:
2023  std::string id; // not serialized: private member
2024  };
2025 ~~~
2026 
2027 By declaring `std::ostream` transient with `extern` you can use this type
2028 wherever you need it without soapcpp2 complaining that this class and any other
2029 class or type declared as `extern` is not defined. Do not use `extern` with
2030 `typedef`, because this declares a custom serializer, see
2031 [adding custom serializers](#custom).
2032 
2033 Marking members transient with `[` and `]` makes them transient (and visually
2034 makes them stand out). This has otherwise no effect on the generated code for
2035 the class or struct to be used in your application code.
2036 
2037 🔝 [Back to table of contents](#)
2038 
2039 ### Derived types in C++ {#toxsd9-1-1}
2040 
2041 Extensible and restricted types in XML schemas are derived types from single
2042 simple and complex base types. XML schema derived types are naturally
2043 represented by C++ derived classes using single inheritance. Besides the
2044 concept of extensions versus restrictions, there are two kinds of derived
2045 types: complexTypes with simpleContent, meaning types with XML CDATA values,
2046 and complexTypes with complexContent, meaning types with sub-elements. Both
2047 are permitted to have one or more XML attributes.
2048 
2049 A complexType with simpleContent is defined as a wrapper to contain XML CDATA
2050 values and any number of attributes, see
2051 [wrapper class/struct with simpleContent](#toxsd10-4).
2052 Wrapper class/struct types can form a hierarchy of derived types in C++ using
2053 inheritance. For example:
2054 
2055 ~~~{.cpp}
2056  class xsd__anyType
2057  { public:
2058  std::string __item; // string to hold any simpleContent
2059  };
2060  class ns__data : public xsd__anyType
2061  { public:
2062  @ std::string value 1; // extends xsd:anyType with a required attribute
2063  };
2064 ~~~
2065 
2066 The `ns__data` class maps to a complexType in the soapcpp2-generated XML schema:
2067 
2068 <div class="alt">
2069 ~~~{.xml}
2070  <complexType name="string">
2071  <simpleContent>
2072  <extension base="xsd:string">
2073  <attribute name="value" type="xsd:string" use="required"/>
2074  </extension>
2075  </simpleContent>
2076  </complexType>
2077 ~~~
2078 </div>
2079 
2080 The XML value space consists of an element with the string contents an optional
2081 attribute:
2082 
2083 <div class="alt">
2084 ~~~{.xml}
2085  <ns:data value="abc">xyz</ns:data>
2086 ~~~
2087 </div>
2088 
2089 By contrast, a complexType with complexContent typically extends a given base
2090 complexType. For example:
2091 
2092 ~~~{.cpp}
2093  class ns__base
2094  { public:
2095  std::string name 1;
2096  int number 1;
2097  };
2098  class ns__derived : public ns__base
2099  { public:
2100  @ std::string value 1; // extends ns:base with an attribute
2101  std::string text 1; // extends ns:base with an element
2102  };
2103 ~~~
2104 
2105 The `ns__base` and `ns__derived` classes maps to complexTypes in the soapcpp2-generated XML schema:
2106 
2107 <div class="alt">
2108 ~~~{.xml}
2109  <complexType name="base">
2110  <sequence>
2111  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2112  <element name="number" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2113  </sequence>
2114  </complexType>
2115  <complexType name="derived">
2116  <complexContent>
2117  <extension base="ns:base">
2118  <sequence>
2119  <element name="text" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2120  </sequence>
2121  </extension>
2122  </complexContent>
2123  <attribute name="value" type="xsd:string" use="required"/>
2124  </complexType>
2125 ~~~
2126 </div>
2127 
2128 The XML value space of `ns__derived` consists of three requires child elements
2129 and an optional attribute:
2130 
2131 <div class="alt">
2132 ~~~{.xml}
2133  <ns:derived value="abc">
2134  <name>def</name>
2135  <number>123</number>
2136  <text>xyz</text>
2137  </ns:derived>
2138 ~~~
2139 </div>
2140 
2141 Derived types can be used for two main purposes in XML schema by extending or
2142 restricting base types. One purpose is to reuse a base type when defining a
2143 derived type, such that common parts do not need to be replicated. The second
2144 purpose is to be able to use a derived type in place of a base type in XML, which
2145 is indicated by an <i>`xsi:type`</i> attribute with the qualified name of the
2146 derived type. Consider for example the following class that uses the
2147 previously declared base types `xsd__anyType` and `ns__base`:
2148 
2149 ~~~{.cpp}
2150  class ns__record
2151  { public:
2152  xsd__anyType *base1 1; // required element
2153  ns__base *base2 1; // required element
2154  };
2155 ~~~
2156 
2157 We can assign base type values to the `ns_record` members:
2158 
2159 ~~~{.cpp}
2160  ns__record record;
2161  record.base1 = soap_new_xsd__anyType(soap);
2162  record.base2 = soap_new_ns__base(soap);
2163  soap_write_ns__record(soap, &record);
2164 ~~~
2165 
2166 This produces the following XML fragment populated with default values (empty
2167 text for strings and zeros for numbers), where element <i>`base1`</i> has a
2168 simpleContent value and element <i>`base2`</i> has two child elements:
2169 
2170 <div class="alt">
2171 ~~~{.xml}
2172  <ns:record>
2173  <base1></base1>
2174  <base2>
2175  <name></name>
2176  <number>0</number>
2177  </base2>
2178  </ns:record>
2179 ~~~
2180 </div>
2181 
2182 We can also assign derived type values to the `ns_record` members:
2183 
2184 ~~~{.cpp}
2185  ns__record record;
2186  record.base1 = soap_new_ns__data(soap);
2187  record.base2 = soap_new_ns__derived(soap);
2188  soap_write_ns__record(soap, &record);
2189 ~~~
2190 
2191 This produces the following XML fragment populated with default values (empty
2192 text for strings and zeros for numbers), where element <i>`base1`</i> has
2193 schema type <i>`ns:data`</i> with simpleContent and an attribute, and
2194 <i>`base2`</i> has schema type <i>`ns:derived`</i> with three child elements
2195 and an attribute:
2196 
2197 <div class="alt">
2198 ~~~{.xml}
2199  <ns:record>
2200  <base1 xsi:type="ns:data" value=""></base1>
2201  <base2 xsi:type="ns:derived" value="">
2202  <name></name>
2203  <number>0</number>
2204  <text></text>
2205  </base2>
2206  </ns:record>
2207 ~~~
2208 </div>
2209 
2210 Deserialization automatically allocates and assigns a `ns__base` class instance to a
2211 `ns__base` pointer when deserializing the <i>`ns:base`</i> schema type and allocates and
2212 assigns a `ns__derived` class instance to a `ns__base` pointer when deserializing the
2213 <i>`ns:derived`</i> type when an element with <i>`xsi:type="ns:derived"`</i> is
2214 parsed. All classes are extended by soapcpp2 by a `soap_type()` method that
2215 returns the unique `SOAP_TYPE_T` value of the class `T`. This makes it easy to
2216 check whether the deserialized data contains a derived type to implement
2217 type-safe code, for example:
2218 
2219 ~~~{.cpp}
2220  ns__record record;
2221  soap_read_ns__record(soap, &record);
2222  if (record.base1->soap_type() == SOAP_TYPE_ns__data)
2223  std::cout << "Derived ns:data "
2224  << dynamic_cast<ns__data*>(record.base1)->value
2225  << std::endl;
2226  else
2227  std::cout << "Base xsd:anyType" << std::endl;
2228  if (record.base2->soap_type() == SOAP_TYPE_ns__derived)
2229  std::cout << "Derived ns:derived "
2230  << dynamic_cast<ns__derived*>(record.base2)->value
2231  << std::endl;
2232  else
2233  std::cout << "Base ns:base" << std::endl;
2234 ~~~
2235 
2236 This example should use the `SOAP_XML_STRICT` mode flag to initialize the
2237 `soap` context to ensure that all required values are present in the
2238 deserialized structures.
2239 
2240 🔝 [Back to table of contents](#)
2241 
2242 ### Derived types in C {#toxsd9-1-2}
2243 
2244 While single inheritance works well in C++ to represent derived types as we
2245 discussed in the previous section, this will obviously not work in C. Two
2246 methods to serialize derived types in C are presented here. The first method
2247 uses `void*` to serialize anything. The second method is more accurate and is
2248 relatively new in gSOAP.
2249 
2250 To serialize any type is possible with [tagged void pointer members](#toxsd9-12) to
2251 serialize data pointed to by a `void*` member, which can be any serializable
2252 type, such as derived types. For `void*` deserialization to work the XML
2253 parsed must contain an <i>`xsi:type`</i> attribute with a schema type. Only
2254 then can the deserializer instantiate the corresponding serializable C/C++
2255 type. Base types serialized do not require an <i>`xsi:type`</i> to indicate
2256 the base schema type, so this approach is not guaranteed to work and requires a
2257 workaround with an anonymous wrapper struct/class that contains both the base
2258 type and a `void*`. For example:
2259 
2260 ~~~{.cpp}
2261  struct ns__base // a base type
2262  {
2263  char *name 1;
2264  int number 1;
2265  };
2266  struct ns__derived // extends ns__base with two additional members
2267  {
2268  char *name 1;
2269  int number 1;
2270  char *text 1;
2271  @ char *value 1;
2272  };
2273  struct __ns__base // a wrapper, not visible in XML
2274  {
2275  int __type; // the SOAP_TYPE_T pointed to by __self
2276  void *__self; // points to any type
2277  struct ns__base *__self; // wraps ns__base for the current element tag
2278  }
2279  class ns__record
2280  {
2281  struct __ns__base base;
2282  };
2283 ~~~
2284 
2285 The `__ns__base` wrapper wraps the `ns__base` type to (de)serialize the
2286 <i>`base`</i> element that has no <i>`xsi:type`</i> attribute and uses `void*`
2287 to (de)serialize the <i>`base`</i> element that has <i>`xsi:type`</i>
2288 attribute. This works fine at the XML parsing level, but the generated
2289 XML schema components do not accurately represent the derived type, because it
2290 lacks the extension/restriction of the derived type (and the `__ns__base`
2291 wrapper is invisible).
2292 
2293 Using `void*` to represent derived types in a base type wrapper is not very
2294 accurate because we can serialize anything, not just derived types of a given
2295 base type. The wrapper may also hold two values: the base type value and a
2296 derived type value. Furthermore, using arrays or containers that hold base and
2297 derived types becomes quite tricky because an array item could hold both the
2298 base and derived type.
2299 
2300 As of gSOAP version 2.8.75, `wsdl2h -F` option `-F` generates base type structs
2301 extended with transient pointer members to its derived types. To serialize the
2302 base type itself, all of the pointer members are NULL. If one of the pointer
2303 members points to a derived type the derived type is serialized instead.
2304 Deserialization is automatic, in that the base type is deserialized if the
2305 element has no <i>`xsi:type`</i> attribute or the attribute is the base schema
2306 type, and a derived type is deserialized if the element has an
2307 <i>`xsi>type`</i> attribute with the derived schema type.
2308 
2309 This method is fully automated for the wsdl2h tool to generate an interface
2310 header file for soapcpp2 with the type derivations in C. To use this method to
2311 generate code from WSDLs and XSDs, use `wsdl2h -F` option `-F`. This also
2312 works in C++ if desired, but C++ inheritance works fine without this method.
2313 
2314 Using this method with soapcpp2 alone using a manually-specified interface
2315 header file produces the specified type inheritance in the soapcpp2-generated
2316 WSDL and XML schema files as complexType extensions.
2317 
2318 The soapcpp2 tool warns if a derived type has multiple base types. At most one
2319 base type for a derived type may be specified.
2320 
2321 This method with transient pointers to derived types makes it easy to use base
2322 and derived types in C:
2323 
2324 ~~~{.cpp}
2325  struct ns__base // a base type
2326  {
2327  char *name 1;
2328  int number 1;
2329  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2330  };
2331  struct ns__derived // extends ns__base with two additional members
2332  {
2333  char *name 1;
2334  int number 1;
2335  char *text 1;
2336  @ char *value 1;
2337  };
2338  struct ns__record
2339  {
2340  struct ns__base base; // contains base type or derived type value
2341  };
2342 ~~~
2343 
2344 The `ns__base` struct includes the special member `ns__derived` that points to
2345 a `ns__derived` value. This special member must be:
2346 
2347 - a transient member (i.e. non-serializable) by placing the declaration within
2348  `[` and `]`, and
2349 - the member name must match the type name (to be more precise, at least the
2350  initial part of the member name must match the type name as in the example
2351  `ns__derived_` works too).
2352 
2353 To serialize the `ns__base` value requires the `ns__derived` member to be NULL.
2354 To serialize the `ns__derived` value requires the `ns__derived` member to point
2355 to the `ns__derived` value to serialize and the `ns__base` members are
2356 irrelevant.
2357 
2358 We can assign the base type value to the `ns_record::base` member:
2359 
2360 ~~~{.cpp}
2361  struct ns__record record;
2362  soap_default_ns__record(soap, &record);
2363  soap_write_ns__record(soap, &record);
2364 ~~~
2365 
2366 This produces the following XML fragment populated with default values (empty
2367 text for strings and zeros for numbers), where element <i>`base`</i> has two
2368 child elements:
2369 
2370 <div class="alt">
2371 ~~~{.xml}
2372  <ns:record>
2373  <base>
2374  <name></name>
2375  <number>0</number>
2376  </base>
2377  </ns:record>
2378 ~~~
2379 </div>
2380 
2381 We can also assign the derived type value to the `ns_record::base` member:
2382 
2383 ~~~{.cpp}
2384  struct ns__record record;
2385  soap_default_ns__record(soap, &record);
2386  record.base.ns__derived = soap_new_ns__derived(soap, -1);
2387  soap_write_ns__record(soap, &record);
2388 ~~~
2389 
2390 This produces the following XML fragment populated with default values (empty
2391 text for strings and zeros for numbers), where element <i>`base`</i> has schema
2392 type <i>`ns:derived`</i> with three child elements and an attribute:
2393 
2394 <div class="alt">
2395 ~~~{.xml}
2396  <ns:record>
2397  <base xsi:type="ns:derived" value="">
2398  <name></name>
2399  <number>0</number>
2400  <text></text>
2401  </base>
2402  </ns:record>
2403 ~~~
2404 </div>
2405 
2406 Deserialization automatically assigns values to the base members for the
2407 `ns__base` type and populates the `ns__derived` member when a derived type with
2408 <i>`xsi:type="ns:derived"`</i> is parsed. This makes it easy to decompose the
2409 deserialized data:
2410 
2411 ~~~{.cpp}
2412  struct ns__record record;
2413  soap_read_ns__record(soap, &record);
2414  if (record.ns__derived)
2415  printf("Derived type with name=%s number=%d text=%s value=%s\n",
2416  record.ns__derived->name,
2417  record.ns__derived->number,
2418  record.ns__derived->text,
2419  record.ns__derived->value);
2420  else
2421  printf("Base type with name=%s number=%d\n",
2422  record.name,
2423  record.number);
2424 ~~~
2425 
2426 This example requires the `SOAP_XML_STRICT` mode flag to initialize the `soap`
2427 context to ensure that all required values are present in the deserialized
2428 structures, otherwise the `char*` strings may be NULL since XML validation
2429 constraints are not enforced on the XML input.
2430 
2431 Deeper levels of simulated inheritance are possible, for example:
2432 
2433 ~~~{.cpp}
2434  struct ns__base // a base type
2435  {
2436  char *name 1;
2437  int number 1;
2438  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2439  };
2440  struct ns__derived // extends ns__base with two additional members
2441  {
2442  char *name 1;
2443  int number 1;
2444  char *text 1;
2445  @ char *value 1;
2446  [ struct ns__derived_derived *ns__derived_derived; ] // points to derived_derived type if non-NULL
2447  };
2448  struct ns__derived_derived // extends ns__derived with an additional member
2449  {
2450  char *name 1;
2451  int number 1;
2452  char *text 1;
2453  @ char *value 1;
2454  @ char *type 1;
2455  };
2456 ~~~
2457 
2458 This requires two pointer traversals from the base type `ns__base` via
2459 `ns__derived` to reach `ns__derived_derived`.
2460 
2461 🔝 [Back to table of contents](#)
2462 
2463 ### Volatile classes and structs {#toxsd9-2}
2464 
2465 Classes and structs can be declared `volatile` in the interface header file for
2466 soapcpp2, which only has meaning for the gSOAP tools. This annotation means
2467 that these types are already declared elsewhere in your project's source code
2468 and you do not want soapcpp2 to generate code with a second declaration of
2469 these types.
2470 
2471 For example, `struct tm` is declared in the <i>`time.h`</i> library. You can
2472 make it serializable and include a partial list of data members that you want
2473 to serialize:
2474 
2475 ~~~{.cpp}
2476  volatile struct tm
2477  {
2478  int tm_sec; // seconds (0 - 60)
2479  int tm_min; // minutes (0 - 59)
2480  int tm_hour; // hours (0 - 23)
2481  int tm_mday; // day of month (1 - 31)
2482  int tm_mon; // month of year (0 - 11)
2483  int tm_year; // year - 1900
2484  };
2485 ~~~
2486 
2487 You can declare classes and structs `volatile` for any such types you want to
2488 serialize by only providing the public data members you want to serialize.
2489 
2490 In addition, [colon notation](#toxsd2) is a simple and effective way to bind an
2491 existing class or struct to a schema. For example, you can change the `tm` name
2492 as follows without affecting the code that uses `struct tm` generated by
2493 soapcpp2:
2494 
2495 ~~~{.cpp}
2496  volatile struct ns:tm { ... }
2497 ~~~
2498 
2499 This struct maps to a complexType in the soapcpp2-generated XML schema:
2500 
2501 <div class="alt">
2502 ~~~{.xml}
2503  <complexType name="tm">
2504  <sequence>
2505  <element name="tm-sec" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2506  <element name="tm-min" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2507  <element name="tm-hour" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2508  <element name="tm-mday" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2509  <element name="tm-mon" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2510  <element name="tm-year" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2511  </sequence>
2512  </complexType>
2513 ~~~
2514 </div>
2515 
2516 🔝 [Back to table of contents](#)
2517 
2518 ### Mutable classes and structs {#toxsd9-3}
2519 
2520 Classes and structs can be declared `mutable` with the gSOAP tools. This means
2521 that their definition can be spread out over the source code. This promotes the
2522 concept of a class or struct as a *row of named values*, also known as a *named
2523 tuple*, that can be extended at compile time in your source code with additional
2524 members. Because these types differ from the traditional object-oriented
2525 principles and design concepts of classes and objects, constructors and
2526 destructors cannot be defined (also because we cannot guarantee merging these
2527 into one such that all members will be initialized). A default constructor,
2528 copy constructor, assignment operation, and destructor will be assigned
2529 automatically by soapcpp2.
2530 
2531 ~~~{.cpp}
2532  mutable struct ns__tuple
2533  {
2534  @ std::string id;
2535  };
2536 
2537  mutable struct ns__tuple
2538  {
2539  std::string name;
2540  std::string value;
2541  };
2542 ~~~
2543 
2544 The members are collected into one definition generated by soapcpp2. Members
2545 may be repeated from one definition to another, but only if their associated
2546 types are identical. So, for example, a third extension with a `value` member
2547 with a different type fails:
2548 
2549 ~~~{.cpp}
2550  mutable struct ns__tuple
2551  {
2552  float value; // BAD: value is already declared std::string
2553  };
2554 ~~~
2555 
2556 The `mutable` concept has proven to be very useful when declaring and
2557 collecting SOAP Headers for multiple services, which are collected into one
2558 `struct SOAP_ENV__Header` by the soapcpp2 tool.
2559 
2560 🔝 [Back to table of contents](#)
2561 
2562 ### Default and fixed member values {#toxsd9-4}
2563 
2564 Class and struct data members in C and C++ may be declared with an optional
2565 default initialization value that is provided "inline" with the declaration of
2566 the member:
2567 
2568 ~~~{.cpp}
2569  class ns__record
2570  { public:
2571  std::string name = "Joe";
2572  ...
2573  };
2574 ~~~
2575 
2576 Alternatively, use C++11 default initialization syntax:
2577 
2578 ~~~{.cpp}
2579  class ns__record
2580  { public:
2581  std::string name { "Joe" };
2582  ...
2583  };
2584 ~~~
2585 
2586 These initializations are made by the default constructor that is added by
2587 soapcpp2 to each class and struct (in C++ only). A constructor is only added
2588 when a default constructor is not already defined with the class declaration.
2589 
2590 You can explicitly (re)initialize an object with these initial values by using
2591 the soapcpp2 auto-generated functions:
2592 
2593 - `void T::soap_default(struct soap*)` for `class T` (C++ only)
2594 
2595 - `void soap_default_T(struct soap*, T*)` for `struct T` (C and C++).
2596 
2597 If `T` is a struct or class that has a `soap` pointer member to a `::soap`
2598 context then this pointer member will be set to the first argument passed to
2599 these functions to initialize their `soap` pointer member.
2600 
2601 Default value initializations can be provided for members that have primitive
2602 types (`bool`, `enum`, `time_t`, numeric and string types).
2603 
2604 Default value initializations of pointer members is permitted, but the effect
2605 is different. To conform to XML schema validation, an attribute member that is
2606 a pointer to a primitive type will be assigned the default value when parsed
2607 from XML. An element member that is a pointer to a primitive type will be
2608 assigned when the element is empty when parsed from XML.
2609 
2610 As of gSOAP 2.8.48 and greater, a fixed value can be assigned with a `==`. A
2611 fixed value is also verified by the parser's validator.
2612 
2613 Default and fixed values for members with or without pointers are best
2614 explained with the following two example fragments.
2615 
2616 A record class (can be a struct in C) with default values for attributes and
2617 elements is declared as follows:
2618 
2619 ~~~{.cpp}
2620  class ns__record_with_default
2621  { public:
2622  @ std::string a = "A"; // optional XML attribute with default value "A"
2623  @ std::string b 1 = "B"; // required XML attribute with default value "B"
2624  @ std::string *c = "C"; // optional XML attribute with default value "C"
2625  std::string d 0 = "D"; // optional XML element with default value "D"
2626  std::string e = "E"; // required XML element with default value "E"
2627  std::string *f = "F"; // optional XML element with default value "F"
2628  ...
2629  };
2630 ~~~
2631 
2632 Attributes are considered optional by default, unless marked as required with
2633 the occurrence constraint `1`. Elements are considered required unless the
2634 member type is a pointer or if the member is marked optional with occurrence
2635 constraint `0`.
2636 
2637 Instead of default values, fixed values indicate that the attribute or element
2638 must contain that value, and only that value, when provided in XML. A fixed
2639 value is specified with a `==`.
2640 
2641 Attributes with default or fixed values may be omitted in XML. When omitted,
2642 the default/fixed value is used at the receiving side, i.e. the deserializer
2643 assigns the default/fixed value when the attribute is absent. Therefore, there
2644 is no need to make attributes with default/fixed values pointer based, because
2645 there is no way to distinguish an omitted attribute from a populated attribute
2646 on the receiving side. The `c` member in the example above can be a
2647 non-pointer for this reason. The wsdl2h tool does not generate pointers for
2648 attributes with default/fixed values.
2649 
2650 Elements with default or fixed values may be optional and the use of
2651 default/fixed values with elements differs from attributes. The default/fixed
2652 value of an element is only used for elements that are empty. Omitted optional
2653 elements are simply absent. No default/fixed value is assigned.
2654 
2655 A record class (can be a struct in C) with fixed values for attributes and
2656 elements is declared as follows:
2657 
2658 ~~~{.cpp}
2659  class ns__record_with_fixed
2660  { public:
2661  @ std::string g == "G"; // optional XML attribute with fixed value "G"
2662  @ std::string h 1 == "H"; // required XML attribute with fixed value "H"
2663  @ std::string *i == "I"; // optional XML attribute with fixed value "I"
2664  std::string j 0 == "J"; // optional XML element with fixed value "J"
2665  std::string k == "K"; // required XML element with fixed value "K"
2666  std::string *l == "L"; // optional XML element with fixed value "L"
2667  ...
2668  };
2669 ~~~
2670 
2671 The XML schema validation rules for the two example classes above are as
2672 follows:
2673 
2674 Member | Notes
2675 ------ | ---------------------------------------------------------------------
2676 `a` | attribute may appear once; if it does not appear its value is "A", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "A")
2677 `b` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "B")
2678 `c` | attribute may appear once; if it does not appear its value is "C", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2679 `d` | element may appear once; if it does not appear or if it is empty, its value is "D"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "D")
2680 `e` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "E")
2681 `f` | element may appear once; if it does not appear it is not provided; if it does appear and it is empty, its value is "F"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2682 `g` | attribute may appear once; if it does not appear its value is "G", if it does not appear its value is "G" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "G")
2683 `h` | attribute must appear once, its value must be "H" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "H")
2684 `i` | attribute may appear once; if it does not appear its value is "I", if it does not appear its value is "I" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2685 `j` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "J")
2686 `k` | element must appear once, its value must be "K" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "K")
2687 `l` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2688 
2689 @see Section [operations on classes and structs](#toxsd9-14).
2690 
2691 🔝 [Back to table of contents](#)
2692 
2693 ### Attribute members {#toxsd9-5}
2694 
2695 Class and struct data members are declared as XML attributes by annotating
2696 their type with a `@` qualifier:
2697 
2698 ~~~{.cpp}
2699  class ns__record
2700  { public:
2701  @ std::string name; // required (non-pointer means required)
2702  @ uint64_t SSN; // required (non-pointer means required)
2703  ns__record *spouse; // optional (pointer means minOccurs=0)
2704  };
2705 ~~~
2706 
2707 This class maps to a complexType in the soapcpp2-generated XML schema:
2708 
2709 <div class="alt">
2710 ~~~{.xml}
2711  <complexType name="record">
2712  <sequence>
2713  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
2714  </sequence>
2715  <attribute name="name" type="xsd:string" use="required"/>
2716  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2717  </complexType>
2718 ~~~
2719 </div>
2720 
2721 An example XML instance of `ns__record` is:
2722 
2723 <div class="alt">
2724 ~~~{.xml}
2725  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2726  <spouse name="Jane" SSN="1987654320">
2727  </spouse>
2728  </ns:record>
2729 ~~~
2730 </div>
2731 
2732 Attribute data members are restricted to primitive types (`bool`, `enum`,
2733 `time_t`, numeric and string types), `xsd__hexBinary`, `xsd__base64Binary`, and
2734 custom serializers, such as `xsd__dateTime`. Custom serializers for types that
2735 may be used as attributes should define `soap_s2T` and `soap_T2s` functions that
2736 convert values of type `T` to strings and back.
2737 
2738 Attribute data members can be pointers and smart pointers to these types, which
2739 permits attributes to be optional.
2740 
2741 🔝 [Back to table of contents](#)
2742 
2743 ### Backtick XML tags {#toxsd9-5-1}
2744 
2745 The XML tag name of a class/struct member is the name of the member with the
2746 usual XML tag translation, see [colon notation](#toxsd2).
2747 
2748 To override the standard translation of identifier names to XML tag names of
2749 attributes and elements, add the XML tag name in backticks (requires gSOAP
2750 2.8.30 or greater):
2751 
2752 ~~~{.cpp}
2753  class ns__record
2754  { public:
2755  @ std::string name `full-name`;
2756  @ uint64_t SSN `tax-id`;
2757  ns__record *spouse `married-to`;
2758  };
2759 ~~~
2760 
2761 This class maps to a complexType in the soapcpp2-generated XML schema:
2762 
2763 <div class="alt">
2764 ~~~{.xml}
2765  <complexType name="record">
2766  <sequence>
2767  <element name="married-to" type="ns:record" minOccurs="0" maxOccurs="1"/>
2768  </sequence>
2769  <attribute name="full-name" type="xsd:string" use="required"/>
2770  <attribute name="tax-id" type="xsd:unsignedLong" use="required"/>
2771  </complexType>
2772 ~~~
2773 </div>
2774 
2775 An example XML instance of `ns__record` is:
2776 
2777 <div class="alt">
2778 ~~~{.xml}
2779  <ns:record xmlns:ns="urn:types" full-name="Joe" tax-id="1234567890">
2780  <married-to full-name="Jane" tax-id="1987654320">
2781  </married-to>
2782  </ns:record>
2783 ~~~
2784 </div>
2785 
2786 A backtick XML tag name may contain any non-empty sequence of ASCII and UTF-8
2787 characters except white space and the backtick character. A backtick tag can
2788 be combined with member constraints and default member initializers:
2789 
2790 ~~~{.cpp}
2791  @ uint64_t SSN `tax-id` 0:1 = 999;
2792 ~~~
2793 
2794 🔝 [Back to table of contents](#)
2795 
2796 ### Qualified and unqualified members {#toxsd9-6}
2797 
2798 Class, struct, and union data members are mapped to namespace qualified or
2799 unqualified tag names of local elements and attributes. If a data member has
2800 no prefix then the default form of qualification is applied based on the
2801 element/attribute form that is declared with the XML schema of the class, struct,
2802 or union type. If the member name has a namespace prefix by colon notation,
2803 then the prefix overrules the default (un)qualified form. Therefore,
2804 [colon notation](#toxsd2) is an effective mechanism to control qualification of
2805 tag names of individual members of classes, structs, and unions.
2806 
2807 The XML schema elementFormDefault and attributeFormDefault declarations control
2808 the tag name qualification of local elements and attributes, respectively.
2809 
2810 - "unqualified" indicates that local elements/attributes are not qualified with
2811  the namespace prefix.
2812 
2813 - "qualified" indicates that local elements/attributes must be qualified with
2814  the namespace prefix.
2815 
2816 Individual schema declarations of local elements and attributes may overrule
2817 this by using the form declaration in an XML schema and by using colon notation
2818 to add namespace prefixes to class, struct, and union members in the header
2819 file for soapcpp2.
2820 
2821 Consider for example an `ns__record` class in the `ns` namespace in which local
2822 elements are qualified and local attributes are unqualified by default:
2823 
2824 ~~~{.cpp}
2825  //gsoap ns schema namespace: urn:types
2826  //gsoap ns schema elementForm: qualified
2827  //gsoap ns schema attributeForm: unqualified
2828  class ns__record
2829  { public:
2830  @ std::string name;
2831  @ uint64_t SSN;
2832  ns__record *spouse;
2833  };
2834 ~~~
2835 
2836 This class maps to a complexType in the soapcpp2-generated XML schema with
2837 targetNamespace "urn:types", elementFormDefault qualified and
2838 attributeFormDefault unqualified:
2839 
2840 <div class="alt">
2841 ~~~{.xml}
2842  <schema targetNamespace="urn:types"
2843  ...
2844  elementFormDefault="qualified"
2845  attributeFormDefault="unqualified"
2846  ... >
2847  <complexType name="record">
2848  <sequence>
2849  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
2850  </sequence>
2851  <attribute name="name" type="xsd:string" use="required"/>
2852  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2853  </complexType>
2854  </schema>
2855 ~~~
2856 </div>
2857 
2858 An example XML instance of `ns__record` is:
2859 
2860 <div class="alt">
2861 ~~~{.xml}
2862  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2863  <ns:spouse> name="Jane" SSN="1987654320">
2864  </ns:spouse>
2865  </ns:record>
2866 ~~~
2867 </div>
2868 
2869 Here the root element <i>`<ns:record>`</i> is qualified because it is a root
2870 element of the XML schema with target namespace "urn:types". Its local element
2871 <i>`<ns:spouse>`</i> is namespace qualified because the elementFormDefault of
2872 local elements is qualified. Attributes are unqualified.
2873 
2874 The default namespace (un)qualification of local elements and attributes can be
2875 overruled by adding a prefix to the member name by using colon notation:
2876 
2877 ~~~{.cpp}
2878  //gsoap ns schema namespace: urn:types
2879  //gsoap ns schema elementForm: qualified
2880  //gsoap ns schema attributeForm: unqualified
2881  class ns__record
2882  { public:
2883  @ std::string ns:name; // 'ns:' qualified
2884  @ uint64_t SSN;
2885  ns__record *:spouse; // ':' unqualified (empty prefix)
2886  };
2887 ~~~
2888 
2889 The colon notation for member <i>`ns:name`</i> forces qualification of its attribute
2890 tag in XML. The colon notation for member <i>`:spouse`</i> removes qualification from
2891 its local element tag:
2892 
2893 <div class="alt">
2894 ~~~{.xml}
2895  <schema targetNamespace="urn:types"
2896  ...
2897  elementFormDefault="unqualified"
2898  attributeFormDefault="unqualified"
2899  ... >
2900  <complexType name="record">
2901  <sequence>
2902  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" form="unqualified"/>
2903  </sequence>
2904  <attribute name="name" type="xsd:string" use="required" form="qualified"/>
2905  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2906  </complexType>
2907  </schema>
2908 ~~~
2909 </div>
2910 
2911 XML instances of `ns__record` have unqualified spouse elements and qualified
2912 ns:name attributes:
2913 
2914 <div class="alt">
2915 ~~~{.xml}
2916  <ns:record xmlns:ns="urn:types" ns:name="Joe" SSN="1234567890">
2917  <spouse> ns:name="Jane" SSN="1987654320">
2918  </spouse>
2919  </ns:record>
2920 ~~~
2921 </div>
2922 
2923 Members of a class or struct can also be prefixed using the `prefix__name`
2924 convention or using colon notation `prefix:name`. However, this has a
2925 different effect by referring to global (root) elements and attributes, see
2926 [document root element definitions](#toxsd9-7).
2927 
2928 [Backtick XML tags](#toxsd9-5-1) can be used in place of the member name
2929 annotations and will achieve the same effect as described when these tag names
2930 are (un)qualified (requires gSOAP 2.8.30 or greater).
2931 
2932 @note You must declare a target namespace with a `//gsoap ns schema namespace:`
2933 directive to enable the `elementForm` and `attributeForm` directives in order
2934 to generate valid XML schemas with soapcpp2. See [directives](#directives) for
2935 more details.
2936 
2937 🔝 [Back to table of contents](#)
2938 
2939 ### Defining document root elements {#toxsd9-7}
2940 
2941 To define and reference XML document root elements we use type names that start
2942 with an underscore:
2943 
2944 ~~~{.cpp}
2945  class _ns__record
2946 ~~~
2947 
2948 Alternatively, we can use a `typedef` to define a document root element with a
2949 given type:
2950 
2951 ~~~{.cpp}
2952  typedef ns__record _ns__record;
2953 ~~~
2954 
2955 This `typedef` maps to a global root element that is added to the
2956 soapcpp2-generated XML schema:
2957 
2958 <div class="alt">
2959 ~~~{.xml}
2960  <element name="record" type="ns:record"/>
2961 ~~~
2962 </div>
2963 
2964 An example XML instance of `_ns__record` is:
2965 
2966 <div class="alt">
2967 ~~~{.xml}
2968  <ns:record xmlns:ns="urn:types">
2969  <name>Joe</name>
2970  <SSN>1234567890</SSN>
2971  <spouse>
2972  <name>Jane</name>
2973  <SSN>1987654320</SSN>
2974  </spouse>
2975  </ns:record>
2976 ~~~
2977 </div>
2978 
2979 Global-level element/attribute definitions are also referenced and/or added to
2980 the generated XML schema when serializable data members reference these by
2981 their qualified name:
2982 
2983 ~~~{.cpp}
2984  typedef std::string _ns__name 1 : 100;
2985  class _ns__record
2986  { public:
2987  @ _QName xsi__type; // built-in XSD attribute xsi:type
2988  _ns__name ns__name; // ref to global ns:name element
2989  uint64_t SSN;
2990  _ns__record *spouse;
2991  };
2992 ~~~
2993 
2994 These types map to the following comonents in the soapcpp2-generated XML
2995 schema:
2996 
2997 <div class="alt">
2998 ~~~{.xml}
2999  <simpleType name="name">
3000  <restriction base="xsd:string">
3001  <minLength value="1"/>
3002  <maxLength value="100"/>
3003  </restriction>
3004  </simpleType>
3005  <element name="name" type="ns:name"/>
3006  <complexType name="record">
3007  <sequence>
3008  <element ref="ns:name" minOccurs="1" maxOccurs="1"/>
3009  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3010  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
3011  </sequence>
3012  <attribute ref="xsi:type" use="optional"/>
3013  </complexType>
3014  <element name="record" type="ns:record"/>
3015 ~~~
3016 </div>
3017 
3018 Use only use qualified member names when their types match the global-level
3019 element types that they refer to. For example:
3020 
3021 ~~~{.cpp}
3022  typedef std::string _ns__name; // global element ns:name of type xsd:string
3023  class _ns__record
3024  { public:
3025  int ns__name; // BAD: global element ns:name is NOT type int
3026  _ns__record ns__record; // OK: ns:record is a global-level root element
3027  ...
3028  };
3029 ~~~
3030 
3031 Therefore, we recommend to use qualified member names only when necessary to
3032 refer to standard XSD elements and attributes, such as `xsi__type`, and
3033 `xsd__lang`.
3034 
3035 By contrast, colon notation has the desired effect to (un)qualify local tag
3036 names by overruling the default element/attribute namespace qualification, see
3037 [qualified and unqualified members](#toxsd9-6).
3038 
3039 As an alternative to prefixing member names, use the backtick tag (requires
3040 gSOAP 2.8.30 or greater):
3041 
3042 ~~~{.cpp}
3043  typedef std::string _ns__name 1 : 100;
3044  class _ns__record
3045  { public:
3046  @ _QName t <i>`xsi:type`</i>; // built-in XSD attribute xsi:type
3047  _ns__name s <i>`ns:name`</i>; // ref to global ns:name element
3048  uint64_t SSN;
3049  _ns__record *spouse;
3050  };
3051 ~~~
3052 
3053 🔝 [Back to table of contents](#)
3054 
3055 ### (Smart) pointer members and their occurrence constraints {#toxsd9-8}
3056 
3057 A public pointer-typed data member is serialized by following its (smart)
3058 pointer(s) to the value pointed to. To serialize pointers to dynamic arrays of
3059 data, please see the next section on
3060 [container and array members and their occurrence constraints](#toxsd9-9).
3061 
3062 Pointers that are NULL and smart pointers that are empty are serialized to
3063 produce omitted element and attribute values, unless an element is required
3064 and is nillable (struct/class members marked with `nullptr`) in which case the
3065 element is rendered as an empty element with <i>`xsi:nil="true"`</i>.
3066 
3067 To control the occurrence requirements of pointer-based data members,
3068 occurrence constraints are associated with data members in the form of a range
3069 `minOccurs : maxOccurs`. For non-repeatable (meaning, not a container or array)
3070 data members, there are only three reasonable occurrence constraints:
3071 
3072 - `0:0` means that this element or attribute is prohibited.
3073 
3074 - `0:1` means that this element or attribute is optional.
3075 
3076 - `1:1` means that this element or attribute is required.
3077 
3078 Pointer-based data members have a default `0:1` occurrence constraint, making
3079 them optional, and their XML schema local element/attribute definition is
3080 marked as nillable. Non-pointer data members have a default `1:1` occurence
3081 constraint, making them required.
3082 
3083 A `nullptr` occurrence constraint may be applicable to required elements that
3084 are nillable pointer types, thus `nullptr 1:1`. This indicates that the
3085 element is nillable (can be `NULL` or `nullptr`). A pointer data member that
3086 is explicitly marked as required and nillable with `nullptr 1:1` will be
3087 serialized as an element with an <i>`xsi:nil`</i> attribute, thus effectively
3088 revealing the NULL property of its value.
3089 
3090 A non-pointer data member that is explicitly marked as optional with `0:1` will
3091 be set to its default value when no XML value is presented to the deserializer.
3092 A default value can be assigned to a data member that has a primitive type or
3093 is a (smart) pointer to primitive type.
3094 
3095 Consider for example:
3096 
3097 ~~~{.cpp}
3098  class ns__record
3099  { public:
3100  std::shared_ptr<std::string> name; // optional (pointer means minOccurs=0)
3101  uint64_t SSN 0:1 = 999; // force optional with default 999
3102  ns__record *spouse nullptr 1:1; // force required and nillabe when absent
3103  };
3104 ~~~
3105 
3106 This class maps to a complexType in the soapcpp2-generated XML schema:
3107 
3108 <div class="alt">
3109 ~~~{.xml}
3110  <complexType name="record">
3111  <sequence>
3112  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3113  <element name="SSN" type="xsd:unsignedLong" minOccurs="0" maxOccurs="1" default="999"/>
3114  <element name="spouse" type="ns:record" minOccurs="1" maxOccurs="1" nillable="true"/>
3115  </sequence>
3116  </complexType>
3117 ~~~
3118 </div>
3119 
3120 An example XML instance of `ns__record` with its `name` string value set to
3121 `Joe`, `SSN` set to its default, and `spouse` set to NULL:
3122 
3123 <div class="alt">
3124 ~~~{.xml}
3125  <ns:record xmlns:ns="urn:types" ...>
3126  <name>Joe</name>
3127  <SSN>999</SSN>
3128  <spouse xsi:nil="true"/>
3129  </ns:record>
3130 ~~~
3131 </div>
3132 
3133 @note In general, a smart pointer is simply declared as a `volatile` template
3134 in a interface header file for soapcpp2:
3135 ~~~{.cpp}
3136  volatile template <class T> class NAMESPACE::shared_ptr;
3137 ~~~
3138 
3139 @note The soapcpp2 tool generates code that uses `NAMESPACE::shared_ptr` and
3140 `NAMESPACE::make_shared` to create shared pointers to objects, where
3141 `NAMESPACE` is any valid C++ namespace such as `std` and `boost` if you have
3142 Boost installed.
3143 
3144 🔝 [Back to table of contents](#)
3145 
3146 ### Container and array members and their occurrence constraints {#toxsd9-9}
3147 
3148 Class and struct data member types that are containers `std::deque`,
3149 `std::list`, `std::vector` and `std::set` are serialized as a collection of
3150 the values they contain. You can also serialize dynamic arrays, which is the
3151 alternative for C to store collections of data. Let's start with STL containers.
3152 
3153 You can use `std::deque`, `std::list`, `std::vector`, and `std::set` containers
3154 by importing:
3155 
3156 ~~~{.cpp}
3157  #import "import/stl.h" // import all containers
3158  #import "import/stldeque.h" // import deque
3159  #import "import/stllist.h" // import list
3160  #import "import/stlvector.h" // import vector
3161  #import "import/stlset.h" // import set
3162 ~~~
3163 
3164 For example, to use a vector data mamber to store names in a record:
3165 
3166 ~~~{.cpp}
3167  #import "import/stlvector.h"
3168  class ns__record
3169  { public:
3170  std::vector<std::string> names;
3171  uint64_t SSN;
3172  };
3173 ~~~
3174 
3175 To limit the number of names in the vector within reasonable bounds, occurrence
3176 constraints are associated with the container. Occurrence constraints are of
3177 the form `minOccurs : maxOccurs`:
3178 
3179 ~~~{.cpp}
3180  #import "import/stlvector.h"
3181  class ns__record
3182  { public:
3183  std::vector<std::string> names 1:10;
3184  uint64_t SSN;
3185  };
3186 ~~~
3187 
3188 This class maps to a complexType in the soapcpp2-generated XML schema:
3189 
3190 <div class="alt">
3191 ~~~{.xml}
3192  <complexType name="record">
3193  <sequence>
3194  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10"/>
3195  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3196  </sequence>
3197  </complexType>
3198 ~~~
3199 </div>
3200 
3201 @note In general, a container is simply declared as a template in an interface
3202 header file for soapcpp2. All class templates are considered containers
3203 (except when declared `volatile`, see smart pointers). For example,
3204 `std::vector` is declared in <i>`gsoap/import/stlvector.h`</i> as:
3205 ~~~{.cpp}
3206  template <class T> class std::vector;
3207 ~~~
3208 
3209 @note You can define and use your own containers. The soapcpp2 tool generates
3210 code that uses the following members of the `template <typename T> class C`
3211 container:
3212 ~~~{.cpp}
3213  void C::clear()
3214  C::iterator C::begin()
3215  C::const_iterator C::begin() const
3216  C::iterator C::end()
3217  C::const_iterator C::end() const
3218  size_t C::size() const
3219  C::iterator C::insert(C::iterator pos, const T& val)
3220 ~~~
3221 
3222 @note For more details see the example `simple_vector` container with
3223 documentation in the package under <i>`gsoap/samples/template`</i>.
3224 
3225 Because C does not support a container template library, we can use a
3226 dynamically-sized array of values. This array is declared as a size-pointer
3227 pair of members within a struct or class. The array size information is stored
3228 in a special size tag member with the name `__size` or `__sizeX`, where `X` can
3229 be any name, or by an `$int` member to identify the member as a special size
3230 tag:
3231 
3232 ~~~{.cpp}
3233  struct ns__record
3234  {
3235  $ int sizeofnames; // array size
3236  char* *names; // array of char* names
3237  uint64_t SSN;
3238  };
3239 ~~~
3240 
3241 This struct maps to a complexType in the soapcpp2-generated XML schema:
3242 
3243 <div class="alt">
3244 ~~~{.xml}
3245  <complexType name="record">
3246  <sequence>
3247  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
3248  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3249  </sequence>
3250  </complexType>
3251 ~~~
3252 </div>
3253 
3254 To limit the number of names in the array within reasonable bounds, occurrence
3255 constraints are associated with the array size member. Occurrence constraints
3256 are of the form `minOccurs : maxOccurs`:
3257 
3258 ~~~{.cpp}
3259  struct ns__record
3260  {
3261  $ int sizeofnames 1:10; // array size 1..10
3262  char* *names; // array of one to ten char* names
3263  uint64_t SSN;
3264  };
3265 ~~~
3266 
3267 This struct maps to a complexType in the soapcpp2-generated XML schema:
3268 
3269 <div class="alt">
3270 ~~~{.xml}
3271  <complexType name="record">
3272  <sequence>
3273  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10" nillable="true"/>
3274  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3275  </sequence>
3276  </complexType>
3277 ~~~
3278 </div>
3279 
3280 Arrays can also be declared as nested elements, similar to SOAP-encoded dynamic arrays, and these arrays can be used with or without SOAP applications. This requires a separate struct or class with the name of the SOAP array, which should not be qualified with a namespace prefix:
3281 
3282 ~~~{.cpp}
3283  struct ArrayOfstring
3284  {
3285  char* *__ptr 1:100; // array of 1..100 strings
3286  int __size; // array size
3287  };
3288  struct ns__record
3289  {
3290  struct ArrayOfstring names; // array of char* names
3291  uint64_t SSN;
3292  };
3293 ~~~
3294 
3295 The `ns__record` struct maps to a complexType that references the <i>`ArrayOfstring`</i> complexType with an sequence of 1 to 100 <i>`item`</i> elements:
3296 
3297 <div class="alt">
3298 ~~~{.xml}
3299  <complexType name="ArrayOfstring">
3300  <sequence>
3301  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3302  </sequence>
3303  </complexType>
3304  <complexType name="record">
3305  <sequence>
3306  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3307  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3308  </sequence>
3309  </complexType>
3310 ~~~
3311 </div>
3312 
3313 To change the <i>`item`</i> element name in the WSDL, XML schema, and XML messages, use `__ptrName` where `Name` is the name you want to use.
3314 
3315 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`ArrayOfstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging:
3316 <div class="alt">
3317 ~~~{.xml}
3318  <import namespace="http://schemas.xmlsoap.org/soap/encoding/"/>
3319  <complexType name="ArrayOfstring">
3320  <complexContent>
3321  <restriction base="SOAP-ENC:Array">
3322  <sequence>
3323  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3324  </sequence>
3325  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="xsd:string[]"/>
3326  </restriction>
3327  </complexContent>
3328  </complexType>
3329  <complexType name="record">
3330  <sequence>
3331  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3332  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3333  </sequence>
3334  </complexType>
3335 ~~~
3336 </div>
3337 
3338 Fixed-size arrays can be used to store a fixed number of values:
3339 
3340 ~~~{.cpp}
3341  struct ns__record
3342  {
3343  char* names[10]; // array of 10 char* names
3344  uint64_t SSN;
3345  };
3346 ~~~
3347 
3348 The fixed-size array is similar to a SOAP-encoded array, which can be used with or without SOAP applications. This struct maps to a complexType that references a <i>`Array10Ofstring`</i> complexType with ten <i>`item`</i> elements:
3349 
3350 <div class="alt">
3351 ~~~{.xml}
3352  <complexType name="record">
3353  <sequence>
3354  <element name="names" type="ns:Array10Ofstring" minOccurs="1" maxOccurs="1"/>
3355  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3356  </sequence>
3357  </complexType>
3358  <complexType name="Array10Ofstring">
3359  <sequence>
3360  <element name="item" type="xsd:string" minOccurs="0" maxOccurs="10"/>
3361  </sequence>
3362  </complexType>
3363 ~~~
3364 </div>
3365 
3366 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`Array10Ofstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging, see previous note.
3367 
3368 🔝 [Back to table of contents](#)
3369 
3370 ### Sequencing with hidden members {#toxsd9-10}
3371 
3372 A member becomes a hidden XML element, i.e. not visibly rendered in XML, when
3373 its name starts with a double underscore. This makes it possible to sequence a
3374 collection of data members, basically by forming a sequence of elements that
3375 can be optional or repeated together.
3376 
3377 To create a sequence of members that are optional, use a pointer-based hidden
3378 member that is a struct with the collection of members to sequence:
3379 
3380 ~~~{.cpp}
3381  struct ns__record
3382  {
3383  std::string name; // required name
3384  struct __ns__optional
3385  {
3386  uint64_t SSN; // SSN in optional group
3387  std::string phone; // phone number in optional group
3388  } *__optional; // optional group
3389  };
3390 ~~~
3391 
3392 Here we used a hidden struct type `__ns__optional` which starts with a double
3393 underscore, because we do not want to define a new global type for the XML
3394 schema we generate. We just need a unique name for a structure that sequences
3395 the two members.
3396 
3397 This struct maps to a complexType in the soapcpp2-generated XML schema:
3398 
3399 <div class="alt">
3400 ~~~{.xml}
3401  <complexType name="record">
3402  <sequence>
3403  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3404  <sequence minOccurs="0" maxOccurs="1">
3405  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3406  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3407  </sequence>
3408  </sequence>
3409  </complexType>
3410 ~~~
3411 </div>
3412 
3413 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3414 The <i>`ns:record`</i> complexType has an optional sequence of `SSN` and
3415 `phone` elements.
3416 
3417 To create repetitions of a sequence of members, use an array as follows:
3418 
3419 ~~~{.cpp}
3420  struct ns__record
3421  {
3422  std::string name; // required name
3423  $ int sizeofarray; // size of group array
3424  struct __ns__array
3425  {
3426  uint64_t SSN; // SSN in group
3427  std::string phone; // phone number in group
3428  } *__array; // group array
3429  };
3430 ~~~
3431 
3432 This struct maps to a complexType in the soapcpp2-generated XML schema:
3433 
3434 <div class="alt">
3435 ~~~{.xml}
3436  <complexType name="record">
3437  <sequence>
3438  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3439  <sequence minOccurs="0" maxOccurs="unbounded">
3440  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3441  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3442  </sequence>
3443  </sequence>
3444  </complexType>
3445 ~~~
3446 </div>
3447 
3448 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3449 The <i>`ns:record`</i> complexType has a potentially unbounded sequence of
3450 `SSN` and `phone` elements. You can specify array bounds instead of zero to
3451 unbounded, see [container and array members and their occurrence constraints](#toxsd9-9).
3452 
3453 The XML value space consists of a sequence of SSN and phone elements:
3454 
3455 <div class="alt">
3456 ~~~{.xml}
3457  <ns:record>
3458  <name>numbers</name>
3459  <SSN>1234567890</SSN>
3460  <phone>555-123-4567</phone>
3461  <SSN>1987654320</SSN>
3462  <phone>555-789-1234</phone>
3463  <SSN>2345678901</SSN>
3464  <phone>555-987-6543</phone>
3465  </ns:record>
3466 ~~~
3467 </div>
3468 
3469 🔝 [Back to table of contents](#)
3470 
3471 ### Tagged union members {#toxsd9-11}
3472 
3473 A union member in a class or in a struct cannot be serialized unless a
3474 discriminating *variant selector* member is provided that tells the serializer
3475 which union field to serialize. This effectively creates a *tagged union*.
3476 
3477 The variant selector is associated with the union as a selector-union pair of members.
3478 The variant selector is a member with the name `__union` or `__unionX`, where
3479 `X` can be any name, or by an `$int` member to identify the member as a variant
3480 selector tag:
3481 
3482 ~~~{.cpp}
3483  class ns__record
3484  { public:
3485  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3486  union ns__choice
3487  {
3488  float x;
3489  int n;
3490  char *s;
3491  } u;
3492  std::string name;
3493  };
3494 ~~~
3495 
3496 The variant selector values are auto-generated based on the union name `choice`
3497 and the names of its members `x`, `n`, and `s`:
3498 
3499 - `xORnORs = SOAP_UNION_ns__choice_x` when `u.x` is valid.
3500 
3501 - `xORnORs = SOAP_UNION_ns__choice_n` when `u.n` is valid.
3502 
3503 - `xORnORs = SOAP_UNION_ns__choice_s` when `u.s` is valid.
3504 
3505 - `xORnORs = 0` when none are valid (should only be used with great care,
3506  because XSD validation may fail when content is required but absent).
3507 
3508 This class maps to a complexType with a sequence and choice in the
3509 soapcpp2-generated XML schema:
3510 
3511 <div class="alt">
3512 ~~~{.xml}
3513  <complexType name="record">
3514  <sequence>
3515  <choice>
3516  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3517  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3518  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3519  </choice>
3520  <element name="names" type="xsd:string" minOccurs="1" maxOccurs="1" nillable="true"/>
3521  </sequence>
3522  </complexType>
3523 ~~~
3524 </div>
3525 
3526 An STL container or dynamic array of a union requires wrapping the variant
3527 selector and union member in a struct:
3528 
3529 ~~~{.cpp}
3530  class ns__record
3531  { public:
3532  std::vector<
3533  struct ns__data // data with a choice of x, n, or s
3534  {
3535  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3536  union ns__choice
3537  {
3538  float x;
3539  int n;
3540  char *s;
3541  } u;
3542  }> data; // vector with data
3543  };
3544 ~~~
3545 
3546 and an equivalent definition with a dynamic array instead of a `std::vector`
3547 (you can use this in C with structs):
3548 
3549 ~~~{.cpp}
3550  class ns__record
3551  { public:
3552  $ int sizeOfdata; // size of dynamic array
3553  struct ns__data // data with a choice of x, n, or s
3554  {
3555  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3556  union ns__choice
3557  {
3558  float x;
3559  int n;
3560  char *s;
3561  } u;
3562  } *data; // points to the data array of length sizeOfdata
3563  };
3564 ~~~
3565 
3566 This maps to two complexTypes in the soapcpp2-generated XML schema:
3567 
3568 <div class="alt">
3569 ~~~{.xml}
3570  <complexType name="data">
3571  <choice>
3572  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3573  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3574  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3575  </choice>
3576  </complexType>
3577  <complexType name="record">
3578  <sequence>
3579  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3580  </sequence>
3581  </complexType>
3582 ~~~
3583 </div>
3584 
3585 The XML value space consists of a sequence of item elements each wrapped in an
3586 data element:
3587 
3588 <div class="alt">
3589 ~~~{.xml}
3590  <ns:record xmlns:ns="urn:types" ...>
3591  <data>
3592  <n>123</n>
3593  </data>
3594  <data>
3595  <x>3.1</x>
3596  </data>
3597  <data>
3598  <s>hello</s>
3599  </data>
3600  <data>
3601  <s>world</s>
3602  </data>
3603  </ns:record>
3604 ~~~
3605 </div>
3606 
3607 To remove the wrapping data element, simply rename the wrapping struct to
3608 `__ns__data` and the member to `__data` to make this member invisible to the
3609 serializer. The double underscore prefix naming convention is used for the
3610 struct name and member name. Also use a dynamic array instead of a STL
3611 container (so you can also use this approach in C with structs):
3612 
3613 ~~~{.cpp}
3614  class ns__record
3615  { public:
3616  $ int sizeOfdata; // size of dynamic array
3617  struct __ns__data // contains choice of x, n, or s
3618  {
3619  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3620  union ns__choice
3621  {
3622  float x;
3623  int n;
3624  char *s;
3625  } u;
3626  } *__data; // points to the data array of length sizeOfdata
3627  };
3628 ~~~
3629 
3630 This maps to a complexType in the soapcpp2-generated XML schema:
3631 
3632 <div class="alt">
3633 ~~~{.xml}
3634  <complexType name="record">
3635  <sequence minOccurs="0" maxOccurs="unbounded">
3636  <choice>
3637  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3638  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3639  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3640  </choice>
3641  </sequence>
3642  </complexType>
3643 ~~~
3644 </div>
3645 
3646 The XML value space consists of a sequence of <i>`<x>`</i>, <i>`<n>`</i>, and/or <i>`<s>`</i>
3647 elements:
3648 
3649 <div class="alt">
3650 ~~~{.xml}
3651  <ns:record xmlns:ns="urn:types" ...>
3652  <n>123</n>
3653  <x>3.1</x>
3654  <s>hello</s>
3655  <s>world</s>
3656  </ns:record>
3657 ~~~
3658 </div>
3659 
3660 Please note that structs, classes, and unions are unnested by soapcpp2 (as in
3661 the C standard of nested structs and unions). Therefore, the `ns__choice`
3662 union in the `ns__record` class is redeclared at the top level despite its
3663 nesting within the `ns__record` class. This means that you will have to choose
3664 a unique name for each nested struct, class, and union.
3665 
3666 🔝 [Back to table of contents](#)
3667 
3668 ### Tagged void pointer members {#toxsd9-12}
3669 
3670 To serialize data pointed to by `void*` requires run-time type information that
3671 tells the serializer what type of data to serialize by means of a *tagged void
3672 pointer*. This type information is stored in a special type tag member of a
3673 struct/class with the name `__type` or `__typeX`, where `X` can be any name, or
3674 alternatively by an `$int` special member of any name as a type tag:
3675 
3676 ~~~{.cpp}
3677  class ns__record
3678  { public:
3679  $ int typeOfdata; // type tag with values SOAP_TYPE_T
3680  void *data; // points to some data of type T
3681  };
3682 ~~~
3683 
3684 A type tag member has nonzero values `SOAP_TYPE_T` where `T` is the name of a
3685 struct/class or the name of a primitive type, such as `int`, `std__string` (for
3686 `std::string`), `string` (for `char*`).
3687 
3688 This class maps to a complexType with a sequence in the soapcpp2-generated
3689 XML schema:
3690 
3691 <div class="alt">
3692 ~~~{.xml}
3693  <complexType name="record">
3694  <sequence>
3695  <element name="data" type="xsd:anyType" minOccurs="0" maxOccurs="1"/>
3696  </sequence>
3697  </complexType>
3698 ~~~
3699 </div>
3700 
3701 The XML value space consists of the XML value space of the type with the
3702 addition of an <i>`xsi:type`</i> attribute to the enveloping element:
3703 
3704 <div class="alt">
3705 ~~~{.xml}
3706  <ns:record xmlns:ns="urn:types" ...>
3707  <data xsi:type="xsd:int">123</data>
3708  </ns:record>
3709 ~~~
3710 </div>
3711 
3712 This <i>`xsi:type`</i> attribute is important for the receiving end to distinguish
3713 the type of data to instantiate. The receiver cannot deserialize the data
3714 without an <i>`xsd:type`</i> attribute.
3715 
3716 You can find the `SOAP_TYPE_T` name of each serializable type in the
3717 auto-generated <i>`soapStub.h`</i> file.
3718 
3719 Also all serializable C++ classes have a virtual `int T::soap_type()` member
3720 that returns their `SOAP_TYPE_T` value that you can use.
3721 
3722 When the `void*` pointer is NULL or when `typeOfdata` is zero, the data is not
3723 serialized.
3724 
3725 An STL container or dynamic array of `void*` pointers to <i>`xsd:anyType`</i> data
3726 requires wrapping the type tag and `void*` members in a struct:
3727 
3728 ~~~{.cpp}
3729  class ns__record
3730  { public:
3731  std::vector<
3732  struct ns__data // data with an xsd:anyType item
3733  {
3734  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3735  void *item; // points to some item of type T
3736  }> data; // vector with data
3737  };
3738 ~~~
3739 
3740 and an equivalent definition with a dynamic array instead of a `std::vector`
3741 (you can use this in C with structs):
3742 
3743 ~~~{.cpp}
3744  class ns__record
3745  { public:
3746  $ int sizeOfdata; // size of dynamic array
3747  struct ns__data // data with an xsd:anyType item
3748  {
3749  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3750  void *item; // points to some item of type T
3751  } *data; // points to the data array of length sizeOfdata
3752  };
3753 ~~~
3754 
3755 This maps to two complexTypes in the soapcpp2-generated XML schema:
3756 
3757 <div class="alt">
3758 ~~~{.xml}
3759  <complexType name="data">
3760  <sequence>
3761  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1" nillable="true"/>
3762  </sequence>
3763  </complexType>
3764  <complexType name="record">
3765  <sequence>
3766  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3767  </sequence>
3768  </complexType>
3769 ~~~
3770 </div>
3771 
3772 The XML value space consists of a sequence of item elements each wrapped in a
3773 data element:
3774 
3775 <div class="alt">
3776 ~~~{.xml}
3777  <ns:record xmlns:ns="urn:types" ...>
3778  <data>
3779  <item xsi:type="xsd:int">123</item>
3780  </data>
3781  <data>
3782  <item xsi:type="xsd:double">3.1</item>
3783  </data>
3784  <data>
3785  <item xsi:type="xsd:string">abc</item>
3786  </data>
3787  </ns:record>
3788 ~~~
3789 </div>
3790 
3791 To remove the wrapping data elements, simply rename the wrapping struct and
3792 member to `__data` to make this member invisible to the serializer with the
3793 double underscore prefix naming convention. Also use a dynamic array instead
3794 of a STL container (you can use this in C with structs):
3795 
3796 ~~~{.cpp}
3797  class ns__record
3798  { public:
3799  $ int sizeOfdata; // size of dynamic array
3800  struct __data // contains xsd:anyType item
3801  {
3802  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3803  void *item; // points to some item of type T
3804  } *__data; // points to the data array of length sizeOfdata
3805  };
3806 ~~~
3807 
3808 This maps to a complexType in the soapcpp2-generated XML schema:
3809 
3810 <div class="alt">
3811 ~~~{.xml}
3812  <complexType name="record">
3813  <sequence minOccurs="0" maxOccurs="unbounded">
3814  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1"/>
3815  </sequence>
3816  </complexType>
3817 ~~~
3818 </div>
3819 
3820 The XML value space consists of a sequence of data elements:
3821 
3822 <div class="alt">
3823 ~~~{.xml}
3824  <ns:record xmlns:ns="urn:types" ...>
3825  <item xsi:type="xsd:int">123</item>
3826  <item xsi:type="xsd:double">3.1</item>
3827  <item xsi:type="xsd:string">abc</item>
3828  </ns:record>
3829 ~~~
3830 </div>
3831 
3832 Again, please note that structs, classes, and unions are unnested by soapcpp2
3833 (as in the C standard of nested structs and unions). Therefore, the `__data`
3834 struct in the `ns__record` class is redeclared at the top level despite its
3835 nesting within the `ns__record` class. This means that you will have to choose
3836 a unique name for each nested struct, class, and union.
3837 
3838 @see Section [XSD type bindings](#typemap2).
3839 
3840 🔝 [Back to table of contents](#)
3841 
3842 ### Adding get and set methods {#toxsd9-13}
3843 
3844 A public `get` method may be added to a class or struct, which will be
3845 triggered by the deserializer. This method will be invoked right after the
3846 instance is populated by the deserializer. The `get` method can be used to
3847 update or verify deserialized content. It should return `SOAP_OK` or set
3848 `soap::error` to a nonzero error code and return it.
3849 
3850 A public `set` method may be added to a class or struct, which will be
3851 triggered by the serializer. The method will be invoked just before the
3852 instance is serialized. Likewise, the `set` method should return `SOAP_OK` or
3853 set set `soap::error` to a nonzero error code and return it.
3854 
3855 For example, adding a `set` and `get` method to a class declaration:
3856 
3857 ~~~{.cpp}
3858  class ns__record
3859  { public:
3860  int set(struct soap*); // triggered before serialization
3861  int get(struct soap*); // triggered after deserialization
3862  ...
3863  };
3864 ~~~
3865 
3866 To add these and othe rmethods to classes and structs with wsdl2h and
3867 <i>`typemap.dat`</i>, please see [class/struct member additions](#typemap3).
3868 
3869 🔝 [Back to table of contents](#)
3870 
3871 ### Operations on classes and structs {#toxsd9-14}
3872 
3873 The following functions/macros are generated by soapcpp2 for each type `T`,
3874 which should make it easier to send, receive, and copy XML data in C and in
3875 C++:
3876 
3877 - `int soap_write_T(struct soap*, T*)` writes an instance of `T` to a file via
3878  file descriptor `int soap::sendfd)` or to a stream via `std::ostream
3879  *soap::os` (C++ only) or saves into a NUL-terminated string by setting
3880  `const char **soap::os` to a string pointer to be set (C only). Returns
3881  `SOAP_OK` on success or an error code, also stored in `soap::error`.
3882 
3883 - `int soap_read_T(struct soap*, T*)` reads an instance of `T` from a file via
3884  file descriptor `int soap::recvfd)` or from a stream via `std::istream
3885  *soap::is` (C++ only) or reads from a NUL-termianted string `const char
3886  *soap::is` (C only). Returns `SOAP_OK` on success or an error code, also
3887  stored in `soap::error`.
3888 
3889 - `void soap_default_T(struct soap*, T*)` sets an instance `T` to its default
3890  value, resetting members of a struct to their initial values (for classes we
3891  use method `T::soap_default`, see below). If `T` is a struct that has a
3892  `soap` pointer member to a `::soap` context then this pointer member will be
3893  set to the first argument passed to this function to initialize its `soap`
3894  pointer member.
3895 
3896 - `T * soap_dup_T(struct soap*, T *dst, const T *src)` (requires <b>`soapcpp2 -Ec`</b>)
3897  deep copy `src` into `dst`, replicating all deep cycles and shared pointers
3898  when a managing `soap` context is provided as argument. When `dst` is NULL,
3899  allocates space for `dst` and returns a pointer to the allocated copy. Deep
3900  copy results in a tree when the `soap` context is NULL, but the presence of
3901  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with
3902  managing context to copy into a tree without cycles and pointers to shared
3903  objects. Returns `dst` or allocated copy when `dst` is NULL.
3904 
3905 - `void soap_del_T(const T*)` (requires <b>`soapcpp2 -Ed`</b>) deletes all
3906  heap-allocated members of this object by deep deletion ONLY IF this object
3907  and all of its (deep) members are not managed by a `soap` context AND the deep
3908  structure is a tree (no cycles and co-referenced objects by way of multiple
3909  (non-smart) pointers pointing to the same data). Can be safely used after
3910  `T * soap_dup_T(NULL, NULL, const T*)` to delete the deep copy returned.
3911  Does not delete the object itself.
3912 
3913 When in C++ mode, soapcpp2 tool adds several methods to classes in addition to
3914 adding a default constructor and destructor (when these were not explicitly
3915 declared).
3916 
3917 The public methods added to a class `T`:
3918 
3919 - `virtual int T::soap_type(void)` returns a unique type ID (`SOAP_TYPE_T`).
3920  This numeric ID can be used to distinguish base from derived instances.
3921 
3922 - `virtual void T::soap_default(struct soap*)` sets all data members to
3923  default values. If class `T` has a `soap` pointer member to a `::soap`
3924  context then this pointer member will be set to the argument passed to this
3925  function to initialize its `soap` pointer member.
3926 
3927 - `virtual void T::soap_serialize(struct soap*) const` serializes object to
3928  prepare for SOAP 1.1/1.2 encoded output (or with `SOAP_XML_GRAPH`) by
3929  analyzing its (cyclic) structures.
3930 
3931 - `virtual int T::soap_put(struct soap*, const char *tag, const char *type) const`
3932  emits object in XML, compliant with SOAP 1.1 encoding style, return error
3933  code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
3934  `soap_end_send(soap)`.
3935 
3936 - `virtual int T::soap_out(struct soap*, const char *tag, int id, const char *type) const`
3937  emits object in XML, with tag and optional id attribute and <i>`xsi:type`</i>,
3938  return error code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
3939  `soap_end_send(soap)`.
3940 
3941 - `virtual void * T::soap_get(struct soap*, const char *tag, const char *type)`
3942  Get object from XML, compliant with SOAP 1.1 encoding style, return pointer
3943  to object or NULL on error. Requires `soap_begin_recv(soap)` and
3944  `soap_end_recv(soap)`.
3945 
3946 - `virtual void *soap_in(struct soap*, const char *tag, const char *type)`
3947  Get object from XML, with matching tag and type (NULL matches any tag and
3948  type), return pointer to object or NULL on error. Requires
3949  `soap_begin_recv(soap)` and `soap_end_recv(soap)`
3950 
3951 - `virtual T * T::soap_alloc(void) const` returns a new object of type `T`,
3952  default initialized and not managed by a `soap` context.
3953 
3954 - `virtual T * T::soap_dup(struct soap*) const` (requires <b>`soapcpp2 -Ec`</b>)
3955  returns a duplicate of this object by deep copying, replicating all deep
3956  cycles and shared pointers when a managing `soap` context is provided as
3957  argument. Deep copy is a tree when argument is NULL, but the presence of
3958  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with the
3959  managing context to copy into a tree without cycles and pointers to shared
3960  objects.
3961 
3962 - `virtual void T::soap_del() const` (rquires <b>`soapcpp2 -Ed`</b>) deletes all
3963  heap-allocated members of this object by deep deletion ONLY IF this object
3964  and all of its (deep) members are not managed by a `soap` context AND the deep
3965  structure is a tree (no cycles and co-referenced objects by way of multiple
3966  (non-smart) pointers pointing to the same data). Can be safely used after
3967  `soap_dup(NULL)` to delete the deep copy. Does not delete the object itself.
3968 
3969 Also, there are four variations of `soap_new_T` for
3970 class/struct/template type `T` that soapcpp2 auto-generates to create instances
3971 on a context-managed heap:
3972 
3973 - `T * soap_new_T(struct soap*)` returns a new instance of `T` with default data
3974  member initializations that are set with the soapcpp2 auto-generated `void
3975  T::soap_default(struct soap*)` method), but ONLY IF the soapcpp2
3976  auto-generated default constructor is used that invokes `soap_default()` and
3977  was not replaced by a user-defined default constructor.
3978 
3979 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
3980  `T`. Similar to the above, instances are initialized.
3981 
3982 - `T * soap_new_req_T(struct soap*, ...)` returns a new instance of `T` and sets
3983  the required data members to the values specified in `...`. The required data
3984  members are those with nonzero minOccurs, see the subsections on
3985  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
3986  [container and array members and their occurrence constraints](#toxsd9-9).
3987 
3988 - `T * soap_new_set_T(struct soap*, ...)` returns a new instance of `T` and sets
3989  the public/serializable data members to the values specified in `...`.
3990 
3991 The above functions can be invoked with a NULL `soap` context, but we will be
3992 responsible to use `delete T` to remove this instance from the unmanaged heap.
3993 
3994 The allocation functions return NULL when memory allocation failed.
3995 
3996 🔝 [Back to table of contents](#)
3997 
3998 Special classes and structs {#toxsd10}
3999 ---------------------------
4000 
4001 The following applies to both structs and classes. The examples show classes
4002 in C++. For C, use structs and omit the C++ features. Structs also require
4003 the use of the `struct` keyword, otherwise soapcpp2 will throw a syntax error.
4004 
4005 ### SOAP-encoded arrays {#toxsd10-1}
4006 
4007 A class or struct with the following layout is a one-dimensional SOAP-encoded
4008 array type:
4009 
4010 ~~~{.cpp}
4011  class ArrayOfT
4012  { public:
4013  T *__ptr; // array pointer
4014  int __size; // array size
4015  };
4016 ~~~
4017 
4018 where `T` is the array element type. A multidimensional SOAP Array is:
4019 
4020 ~~~{.cpp}
4021  class ArrayOfT
4022  { public:
4023  T *__ptr; // array pointer
4024  int __size[N]; // array size of each dimension
4025  };
4026 ~~~
4027 
4028 where `N` is the constant number of dimensions. The pointer points to an array
4029 of `__size[0]*__size[1]* ... * __size[N-1]` elements.
4030 
4031 This maps to a complexType restriction of SOAP-ENC:Array in the
4032 soapcpp2-generated XML schema:
4033 
4034 <div class="alt">
4035 ~~~{.xml}
4036  <complexType name="ArrayOfT">
4037  <complexContent>
4038  <restriction base="SOAP-ENC:Array">
4039  <sequence>
4040  <element name="item" type="T" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
4041  </sequence>
4042  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="ArrayOfT[]"/>
4043  </restriction>
4044  </complexContent>
4045  </complexType>
4046 ~~~
4047 </div>
4048 
4049 The name of the class can be arbitrary. We often use `ArrayOfT` without a
4050 prefix to distinguish arrays from other classes and structs.
4051 
4052 With SOAP 1.1 encoding, an optional offset member can be added that controls
4053 the start of the index range for each dimension:
4054 
4055 ~~~{.cpp}
4056  class ArrayOfT
4057  { public:
4058  T *__ptr; // array pointer
4059  int __size[N]; // array size of each dimension
4060  int __offset[N]; // array offsets to start each dimension
4061  };
4062 ~~~
4063 
4064 For example, we can define a matrix of floats as follows:
4065 
4066 ~~~{.cpp}
4067  class Matrix
4068  { public:
4069  double *__ptr;
4070  int __size[2];
4071  };
4072 ~~~
4073 
4074 The following code populates the matrix and serializes it in XML:
4075 
4076 ~~~{.cpp}
4077  soap *soap = soap_new1(SOAP_XML_INDENT);
4078  Matrix A;
4079  double a[6] = { 1, 2, 3, 4, 5, 6 };
4080  A.__ptr = a;
4081  A.__size[0] = 2;
4082  A.__size[1] = 3;
4083  soap_write_Matrix(soap, &A);
4084 ~~~
4085 
4086 Matrix A is serialized as an array with 2x3 values:
4087 
4088 <div class="alt">
4089 ~~~{.xml}
4090  <SOAP-ENC:Array SOAP-ENC:arrayType="xsd:double[2,3]" ...>
4091  <item>1</item>
4092  <item>2</item>
4093  <item>3</item>
4094  <item>4</item>
4095  <item>5</item>
4096  <item>6</item>
4097  </SOAP-ENC:Array>
4098 ~~~
4099 </div>
4100 
4101 🔝 [Back to table of contents](#)
4102 
4103 ### XSD hexBinary and base64Binary types {#toxsd10-2}
4104 
4105 A special case of a one-dimensional array is used to define <i>`xsd:hexBinary`</i> and
4106 <i>`xsd:base64Binary`</i> types when the pointer type is `unsigned char`:
4107 
4108 ~~~{.cpp}
4109  class xsd__hexBinary
4110  { public:
4111  unsigned char *__ptr; // points to raw binary data
4112  int __size; // size of data
4113  };
4114 ~~~
4115 
4116 and
4117 
4118 ~~~{.cpp}
4119  class xsd__base64Binary
4120  { public:
4121  unsigned char *__ptr; // points to raw binary data
4122  int __size; // size of data
4123  };
4124 ~~~
4125 
4126 To create a new binary type, use either one of the following three forms that
4127 declare a new `ns__binary` type that is a <i>`simpleType`</i> restriction of
4128 <i>`xsd:base64Binary`</i>:
4129 
4130 ~~~{.cpp}
4131  typedef xsd__base64Binary ns__binary;
4132 ~~~
4133 ~~~{.cpp}
4134  class ns__binary : public xsd__base64Binary
4135  {
4136  ... // attribute members (@) and class methods
4137  };
4138 ~~~
4139 ~~~{.cpp}
4140  class ns__binary
4141  { public:
4142  unsigned char *__ptr; // points to raw binary data
4143  int __size; // size of data
4144  ... // attribute members (@) and class methods (optional)
4145  };
4146 ~~~
4147 
4148 Here, `xsd__base64Binary` is reused in the first two cases, where
4149 `xsd__base64Binary` is declared as shown above.
4150 
4151 @see [DIME/MIME/MTOM attachment binary types](#toxsd10-3)
4152 
4153 🔝 [Back to table of contents](#)
4154 
4155 ### DIME/MIME/MTOM attachment binary types {#toxsd10-3}
4156 
4157 A class or struct with a binary content layout can be extended to support
4158 attachments. The following struct or class type can be used as DIME, MIME, and
4159 MTOM attachment and also be used for <i>`xsd:base64Binary`</i> type values:
4160 
4161 ~~~{.cpp}
4162  class xsd__base64Binary
4163  { public:
4164  unsigned char *__ptr; // points to raw binary data
4165  int __size; // size of data
4166  char *id; // NULL to generate an id, or set to a unique UUID
4167  char *type; // MIME type of the data
4168  char *options; // optional description of MIME attachment
4169  };
4170 ~~~
4171 
4172 When the `id`, `type`, or `options` members are non-NULL, an attachment will be
4173 used instead of base64 XML content. DIME attachments are the default. To
4174 switch to MIME use the `SOAP_ENC_MIME` context flag. To switch to MTOM use the
4175 `SOAP_ENC_MTOM` context flag.
4176 
4177 MTOM is typically used with XOP <i>`<xop:Include>`</i> elements, which is
4178 preferred and declared as follows:
4179 
4180 ~~~{.cpp}
4181  //gsoap xop schema import: http://www.w3.org/2004/08/xop/include
4182  class _xop__Include
4183  { public:
4184  unsigned char *__ptr; // points to raw binary data
4185  int __size; // size of data
4186  char *id; // NULL to generate an id, or set to a unique UUID
4187  char *type; // MIME type of the data
4188  char *options; // optional description of MIME attachment
4189  };
4190 ~~~
4191 
4192 Attachments are beyond the scope of this article. See the
4193 [gSOAP user guide.](../../guide/html/index.html) for more details.
4194 
4195 🔝 [Back to table of contents](#)
4196 
4197 ### Wrapper class/struct with simpleContent {#toxsd10-4}
4198 
4199 A class or struct with the following layout is a complexType that wraps
4200 simpleContent:
4201 
4202 ~~~{.cpp}
4203  class ns__simple
4204  { public:
4205  T __item; // primitive type for the simpleContent
4206  ... // attribute members (@) and class methods (optional)
4207  };
4208 ~~~
4209 
4210 The type `T` is a primitive type (`bool`, `enum`, `time_t`, numeric and string
4211 types), `xsd__hexBinary`, `xsd__base64Binary`, and custom serializers, such as
4212 `xsd__dateTime`.
4213 
4214 This maps to a complexType with simpleContent in the soapcpp2-generated XML
4215 schema:
4216 
4217 <div class="alt">
4218 ~~~{.xml}
4219  <complexType name="simple">
4220  <simpleContent>
4221  <extension base="T"/>
4222  </simpleContent>
4223  </complexType>
4224 ~~~
4225 </div>
4226 
4227 A wrapper class/struct may include any number of members that are declared as
4228 attributes with `@`, which should be placed after the `__item` member.
4229 
4230 🔝 [Back to table of contents](#)
4231 
4232 ### DOM anyType and anyAttribute {#toxsd10-5}
4233 
4234 Use of a DOM is optional and enabled by `#import "dom.h"` to use the DOM
4235 `xsd__anyType` element node and `xsd__anyAttribute` attribute node:
4236 
4237 ~~~{.cpp}
4238  #import "dom.h"
4239 
4240  class ns__record
4241  { public:
4242  @ xsd__anyAttribute attributes; // optional DOM attributes
4243  xsd__anyType *name; // optional DOM element (pointer means minOccurs=0)
4244  xsd__anyType address; // required DOM element (minOccurs=1)
4245  xsd__anyType email 0; // optional DOM element (minOccurs=0)
4246  ... // other members
4247  };
4248 ~~~
4249 
4250 where `name` contains XML stored in a DOM node set and `attributes` is a list
4251 of all visibly rendered attributes. The name `attributes` is arbitrary and any
4252 name will suffice.
4253 
4254 You should place the `xsd__anyType` members at the end of the struct or class.
4255 This ensures that the DOM members are populated last as a "catch all". A
4256 member name starting with double underscore is a wildcard member. These
4257 members are placed at the end of a struct or class automatically by soapcpp2.
4258 
4259 An `#import "dom.h"` import is automatically added by <b>`wsdl2h -d`</b> with
4260 option <b>`-d`</b> to bind <i>`xsd:anyType`</i> to DOM nodes, and also to
4261 populate <i>`xsd:any`</i>, <i>`xsd:anyAttribute`</i> and <i>`xsd:mixed`</i> XML
4262 content:
4263 
4264 ~~~{.cpp}
4265  #import "dom.h"
4266 
4267  class ns__record
4268  { public:
4269  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4270  std::vector<xsd__anyType> __any 0; // optional DOM elements (minOccurs=0)
4271  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4272  ... // other members
4273  };
4274 ~~~
4275 
4276 where the members prefixed with `__` are "invisible" to the XML parser, meaning
4277 that these members are not bound to XML tag names.
4278 
4279 In C you can use a dynamic arrary instead of `std::vector`:
4280 
4281 ~~~{.cpp}
4282  #import "dom.h"
4283 
4284  struct ns__record
4285  {
4286  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4287  $ int __sizeOfany; // size of the array
4288  xsd__anyType *__any; // optional DOM elements (pointer means minOccurs=0)
4289  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4290  ... // other members
4291  };
4292 ~~~
4293 
4294 Classes can inherit DOM, which enables full use of polymorphism with one base
4295 DOM class:
4296 
4297 ~~~{.cpp}
4298  #import "dom.h"
4299 
4300  class ns__record : public xsd__anyType
4301  { public:
4302  std::vector<xsd__anyType*> array; // array of objects of any class
4303  ... // other members
4304  };
4305 ~~~
4306 
4307 This permits an `xsd__anyType` pointer to refer to a derived class such as
4308 `ns__record`, which will be serialized with an <i>`xsi:type`</i> attribute that is
4309 set to "ns:record". The <i>`xsi:type`</i> attributes add the necessary type information
4310 to distinguish the XML content from the DOM base type. This is important for
4311 the receiving end: without <i>`xsd:type`</i> attributes with type names, only base DOM
4312 objects are recognized and instantiated.
4313 
4314 Because C lacks object-oriented programming concepts such as class inheritance
4315 and polymorphism, you should consider using [derived types in C and C++](#toxsd9-1-1).
4316 
4317 An alternative is to use the special [tagged void pointer members](#toxsd9-12)
4318 to serialize data pointed to by a `void*` member, which can be any serializable
4319 type, such as derived types. This approach uses <i>`xsi:type`</i> attributes
4320 to identify the type of value serialized.
4321 
4322 To ensure that wsdl2h generates pointer-based `xsd__anyType` DOM nodes with
4323 <b>`wsdl2h -d`</b> using option <b>`-d`</b> for <i>`xsd:any`</i>, add the
4324 following line to <i>`typemap.dat`</i>:
4325 
4326  xsd__any = | xsd__anyType*
4327 
4328 This lets wsdl2h produce class/struct members and containers with
4329 `xsd__anyType*` for <i>`xsd:any`</i> instead of `xsd__anyType`. To just force all
4330 <i>`xsd:anyType`</i> uses to be pointer-based, declare in <i>`typemap.dat`</i>:
4331 
4332  xsd__anyType = | xsd__anyType*
4333 
4334 If you use <b>`wsdl2h -d -p`</b> using options <b>`-d`</b> and <b>`-p`</b> then
4335 every class will inherit DOM as shown above. Without option `-d`, an
4336 `xsd__anyType` type is generated to serve as the root type in the type
4337 hierarchy:
4338 
4339 ~~~{.cpp}
4340  class xsd__anyType { _XML __item; struct soap *soap; };
4341 
4342  class ns__record : public xsd__anyType
4343  {
4344  ...
4345  };
4346 ~~~
4347 
4348 where the `_XML __item` member holds any XML content as a literal XML string.
4349 
4350 To use the DOM API, compile <i>`dom.c`</i> (or <i>`dom.cpp`</i> for C++), or
4351 link the gSOAP library with <b>`-lgsoapssl`</b> (or <b>`-lgsoapssl++`</b> for C++).
4352 
4353 @see Documentation of [XML DOM and XPath](http://www.genivia.com/doc/dom/html)
4354 for more details.
4355 
4356 🔝 [Back to table of contents](#)
4357 
4358 Directives {#directives}
4359 ==========
4360 
4361 You can use `//gsoap` directives in the interface header file with the data
4362 binding interface for soapcpp2. These directives are used to configure the
4363 code generated by soapcpp2 by declaring various. properties of Web services
4364 and XML schemas. When using the wsdl2h tool, you will notice that wsdl2h
4365 generates directives automatically based on the WSDL and XSD input.
4366 
4367 Service directives are applicable to service and operations described by WSDL.
4368 Schema directives are applicable to types, elements, and attributes defined by
4369 XML schemas.
4370 
4371 🔝 [Back to table of contents](#)
4372 
4373 Service directives {#directives-1}
4374 ------------------
4375 
4376 A service directive must start at a new line and is of the form:
4377 
4378 ~~~{.cpp}
4379  //gsoap <prefix> service <property>: <value>
4380 ~~~
4381 
4382 where `<prefix>` is the XML namespace prefix of a service binding. The
4383 `<property>` and `<value>` fields are one of the following:
4384 
4385 property | value
4386 --------------- | -----
4387 `name` | name of the service, optionally followed by text describing the service
4388 `namespace` | URI of the WSDL targetNamespace
4389 `documentation` | text describing the service (see also the `name` property), multiple permitted
4390 `doc` | an alias for the `documentation` property
4391 `style` | `document` (default) SOAP messaging style or `rpc` for SOAP RPC
4392 `encoding` | `literal` (default), `encoded` for SOAP encoding, or a custom URI
4393 `protocol` | specifies SOAP or REST, see below
4394 `port` | URL of the service endpoint, usually an http or https address, to use in the WSDL definitions/service/port/address/\@location
4395 `location` | an alias for the `port` property
4396 `endpoint` | an alias for the `port` property
4397 `transport` | URI declaration of the transport, usually `http://schemas.xmlsoap.org/soap/http`
4398 `definitions` | name of the WSDL definitions/\@name
4399 `type` | name of the WSDL definitions/portType/\@name (WSDL2.0 interface/\@name)
4400 `portType` | an alias for the `type` property (`portType` follows SOAP 1.1 naming conventions)
4401 `interface` | an alias for the `type` property (`interface` follows SOAP 1.2 naming conventions)
4402 `binding` | name of the WSDL definitions/binding/\@name
4403 `portName` | name of the WSDL definitions/service/port/\@name
4404 `executable` | name of the "executable" to use in the WSDL definitions/service/port/address/\@location
4405 
4406 The service `name` and `namespace` properties are required in order to generate
4407 a valid WSDL with soapcpp2. The other properties are optional.
4408 
4409 The `style` and `encoding` property defaults are changed with
4410 <b>`soapcpp2 -e`</b> option <b>`-e`</b> to `rpc` and `encoded`, respectively.
4411 
4412 The `protocol` property is `SOAP` by default (SOAP 1.1). Protocol property
4413 values are:
4414 
4415 protocol value | description
4416 -------------- | -----------
4417 `SOAP` | SOAP transport, supporting both SOAP 1.1 and 1.2
4418 `SOAP1.1` | SOAP 1.1 transport (same as `soapcpp2 -1`)
4419 `SOAP1.2` | SOAP 1.2 transport (same as `soapcpp2 -2`)
4420 `SOAP-GET` | one-way SOAP 1.1 or 1.2 with HTTP GET
4421 `SOAP1.1-GET` | one-way SOAP 1.1 with HTTP GET
4422 `SOAP1.2-GET` | one-way SOAP 1.2 with HTTP GET
4423 `HTTP` | non-SOAP REST protocol with HTTP POST
4424 `POST` | non-SOAP REST protocol with HTTP POST
4425 `GET` | non-SOAP REST protocol with HTTP GET
4426 `PUT` | non-SOAP REST protocol with HTTP PUT
4427 `DELETE` | non-SOAP REST protocol with HTTP DELETE
4428 
4429 You can bind service operations to the WSDL namespace of a service by using the
4430 namespace prefix as part of the identifier name of the function that defines
4431 the service operation:
4432 
4433 ~~~{.cpp}
4434  int prefix__func(arg1, arg2, ..., argn, result);
4435 ~~~
4436 
4437 You can override the `port` endpoint URL at runtime in the auto-generated
4438 `soap_call_prefix__func` service call (C/C++ client side) and in the C++ proxy
4439 class service call.
4440 
4441 🔝 [Back to table of contents](#)
4442 
4443 Service method directives {#directives-2}
4444 -------------------------
4445 
4446 Service properties are applicable to a service and to all of its operations.
4447 Service method directives are specifically applicable to a service operation.
4448 
4449 A service method directive is of the form:
4450 
4451 ~~~{.cpp}
4452  //gsoap <prefix> service method-<property>: <method> <value>
4453 ~~~
4454 
4455 where `<prefix>` is the XML namespace prefix of a service binding and
4456 `<method>` is the unqualified name of a service operation. The `<property>`
4457 and `<value>` fields are one of the following:
4458 
4459 method property | value
4460 --------------------------- | -----
4461 `method-documentation` | text describing the service operation
4462 `method` | an alias for the `method-documentation` property
4463 `method-action` | `""` or URI SOAPAction HTTP header, or URL query string for REST protocols
4464 `method-input-action` | `""` or URI SOAPAction HTTP header of service request messages
4465 `method-output-action` | `""` or URI SOAPAction HTTP header of service response messages
4466 `method-fault-action` | `""` or URI SOAPAction HTTP header of service fault messages
4467 `method-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Header
4468 `method-input-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of requests
4469 `method-output-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of responses
4470 `method-fault` | type name of a struct or class member used in `SOAP_ENV__Details` struct
4471 `method-mime-type` | REST content type or SOAP MIME attachment content type(s)
4472 `method-input-mime-type` | REST content type or SOAP MIME attachment content type(s) of request message
4473 `method-output-mime-type` | REST content type or SOAP MIME attachment content type(s) of response message
4474 `method-style` | `document` or `rpc`
4475 `method-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of messages
4476 `method-response-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of response messages
4477 `method-protocol` | SOAP or REST, see [service directives](#directives-1)
4478 
4479 The `method-header-part` properties can be repeated for a service operation to
4480 declare multiple SOAP Header parts that the service operation requires. You
4481 can use `method-input-header-part` and `method-output-header-part` to
4482 differentiate between request and response messages.
4483 
4484 The `method-fault` property can be repeated for a service operation to declare
4485 multiple faults that the service operation may return.
4486 
4487 The `method-action` property serves two purposes:
4488 
4489 -# To set the SOAPAction header for SOAP protocols, i.e. sets the
4490  definitions/binding/operation/SOAP:operation/\@soapAction.
4491 
4492 -# To set the URL query string for endpoints with REST protocols, i.e. sets the
4493  definitions/binding/operation/HTTP:operation/\@location, which specifies
4494  a URL query string (starts with a `?`) to complete the service endpoint URL
4495  or extends the endpoint URL with a local path (starts with a `/`).
4496 
4497 Use `method-input-action` and `method-output-action` to differentiate the
4498 SOAPAction between SOAP request and response messages.
4499 
4500 You can always override the port endpoint URL and action values at runtime in
4501 the auto-generated `soap_call_prefix__func` service call (C/C++ client side)
4502 and in the auto-generated C++ proxy class service calls. A runtime NULL
4503 endpoint URL and/or action uses the defaults set by these directives.
4504 
4505 The `method-mime-type` property serves two purposes:
4506 
4507 -# To set the type of MIME/MTOM attachments used with SOAP protocols. Multiple
4508  attachment types can be declared for a SOAP service operation, i.e. adds
4509  definitions/binding/operation/input/MIME:multipartRelated/MIME:part/MIME:content/\@type
4510  for each type specified.
4511 
4512 -# To set the MIME type of a REST operation. This replaces XML declared in
4513  WSDL by definitions/binding/operation/(input|output)/MIME:mimeXml with
4514  MIME:content/\@type. Use `application/x-www-form-urlencoded` with REST POST
4515  and PUT protocols to send encoded form data automatically instead of XML.
4516  Only primitive type values can be transmitted with form data, such as
4517  numbers and strings, i.e. only types that are legal to use as
4518  [attributes members](#toxsd9-5).
4519 
4520 Use `method-input-mime-type` and `method-output-mime-type` to differentiate the
4521 attachment types between request and response messages.
4522 
4523 🔝 [Back to table of contents](#)
4524 
4525 Schema directives {#directives-3}
4526 -----------------
4527 
4528 A schema directive is of the form:
4529 
4530 ~~~{.cpp}
4531  //gsoap <prefix> schema <property>: <value>
4532 ~~~
4533 
4534 where `<prefix>` is the XML namespace prefix of a schema. The `<property>` and
4535 `<value>` fields are one of the following:
4536 
4537 property | value
4538 --------------- | -----
4539 `namespace` | URI of the XSD targetNamespace
4540 `namespace2` | alternate URI pattern for the XSD namespace (i.e. URI is also accepted by the XML parser)
4541 `import` | URI of an imported namespace, as an alternative or in addition to `namespace`, adds `xsd:import` to the generated WSDL and XSD files
4542 `form` | `unqualified` (default) or `qualified` local element and attribute form defaults
4543 `elementForm` | `unqualified` (default) or `qualified` local element form default
4544 `attributeForm` | `unqualified` (default) or `qualified` local attribute form default
4545 `typed` | `no` (default) or `yes` for serializers to add `xsi:type` attributes to XML
4546 
4547 To learn more about the local form defaults, see [qualified and unqualified members.](#toxsd9-6)
4548 
4549 The `namespace2` URI is a pattern with `*` matching any sequence of characters
4550 and `-` matching any character. This pattern instructs the XML parser and validator
4551 to also accept the URI pattern as a valid namespace for the specified `<prefix>`.
4552 
4553 The `typed` property is implicitly `yes` when <b>`soapcpp2 -t`</b> option <b>`-t`</b> is used.
4554 
4555 🔝 [Back to table of contents](#)
4556 
4557 Schema type directives {#directives-4}
4558 ----------------------
4559 
4560 A schema type directive is of the form:
4561 
4562 ~~~{.cpp}
4563  //gsoap <prefix> schema type-<property>: <name> <value>
4564  //gsoap <prefix> schema type-<property>: <name>::<member> <value>
4565 ~~~
4566 
4567 where `<prefix>` is the XML namespace prefix of a schema and `<name>` is an
4568 unqualified name of a C/C++ type, and the optional `<member>` is a class/struct
4569 members or enum constant.
4570 
4571 You can describe a type with one of the following:
4572 
4573 type property | value
4574 -------------------- | -----
4575 `type-documentation` | text describing the schema type
4576 `type` | an alias for the `type-documentation` property
4577 
4578 For example, you can add a description to an enumeration:
4579 
4580 ~~~{.cpp}
4581  //gsoap ns schema type: Vowels The letters A, E, I, O, U, and sometimes Y
4582  //gsoap ns schema type: Vowels::Y A vowel, sometimes
4583  enum class ns__Vowels : char { A = 'A', E = 'E', I = 'I', O = 'O', U = 'U', Y = 'Y' };
4584 ~~~
4585 
4586 This documented enumeration maps to a simpleType restriction of <i>`xsd:string`</i> in
4587 the soapcpp2-generated schema:
4588 
4589 <div class="alt">
4590 ~~~{.xml}
4591  <simpleType name="Vowels">
4592  <annotation>
4593  <documentation>The letters A, E, I, O, U, and sometimes Y</documentation>
4594  </annotation>
4595  <restriction base="xsd:string">
4596  <enumeration value="A"/>
4597  <enumeration value="E"/>
4598  <enumeration value="I"/>
4599  <enumeration value="O"/>
4600  <enumeration value="U"/>
4601  <enumeration value="Y">
4602  <annotation>
4603  <documentation>A vowel, sometimes</documentation>
4604  </annotation>
4605  <enumeration/>
4606  </restriction>
4607  </simpleType>
4608 ~~~
4609 </div>
4610 
4611 🔝 [Back to table of contents](#)
4612 
4613 Serialization rules {#rules}
4614 ===================
4615 
4616 A presentation on XML data bindings is not complete without discussing the
4617 serialization rules and options that put your data in XML on the wire or store
4618 it a file or buffer.
4619 
4620 There are several options to choose from to serialize data in XML. The choice
4621 depends on the use of the SOAP protocol or if SOAP is not required. The wsdl2h
4622 tool automates this for you by taking the WSDL transport bindings into account
4623 when generating the service functions in C and C++ that use SOAP or REST.
4624 
4625 The gSOAP tools are not limited to SOAP. The tools implement generic XML data
4626 bindings for SOAP, REST, and other uses of XML. So you can read and write XML
4627 using the serializing [operations on classes and structs](#toxsd9-14).
4628 
4629 The following sections briefly explain the serialization rules with respect to
4630 the SOAP protocol for XML Web services. A basic understanding of the SOAP
4631 protocol is useful when developing client and server applications that must
4632 interoperate with other SOAP applications.
4633 
4634 SOAP/REST Web service client and service operations are represented as
4635 functions in your interface header file with the data binding interface for
4636 soapcpp2. The soapcpp2 tool will translate these function to client-side
4637 service invocation calls and server-side service operation dispatchers.
4638 
4639 A discussion of SOAP clients and servers is beyond the scope of this article.
4640 However, the SOAP options discussed here also apply to SOAP client and server
4641 development.
4642 
4643 🔝 [Back to table of contents](#)
4644 
4645 SOAP document versus rpc style {#doc-rpc}
4646 ------------------------------
4647 
4648 The `wsdl:binding/soap:binding/@style` attribute in the <i>`<wsdl:binding>`</i>
4649 section of a WSDL is either "document" or "rpc". The "rpc" style refers to
4650 SOAP RPC (Remote Procedure Call), which is more restrictive than the "document"
4651 style by requiring one XML element in the SOAP Body to act as the procedure
4652 name with XML subelements as its parameters.
4653 
4654 For example, the following directives in the interface header file for soapcpp2
4655 declare that `DBupdate` is a SOAP RPC encoding service method:
4656 
4657 ~~~{.cpp}
4658  //gsoap ns service namespace: urn:DB
4659  //gsoap ns service method-protocol: DBupdate SOAP
4660  //gsoap ns service method-style: DBupdate rpc
4661  int ns__DBupdate(...);
4662 ~~~
4663 
4664 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4665 one element representing the operation with the parameters as subelements:
4666 
4667 <div class="alt">
4668 ~~~{.xml}
4669  <SOAP-ENV:Envelope
4670  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4671  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4672  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4673  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4674  xmlsn:ns="urn:DB">
4675  <SOAP-ENV:Body>
4676  <ns:DBupdate>
4677  ...
4678  </ns:DBupdate>
4679  </SOAP-ENV:Body>
4680  </SOAP-ENV:Envelope>
4681 ~~~
4682 </div>
4683 
4684 The "document" style puts no restrictions on the SOAP Body content. However, we
4685 recommend that the first element's tag name in the SOAP Body should be unique
4686 to each type of operation, so that the receiver can dispatch the operation
4687 based on this element's tag name. Alternatively, the HTTP URL path can be used
4688 to specify the operation, or the HTTP action header can be used to dispatch
4689 operations automatically on the server side (soapcpp2 options -a and -A).
4690 
4691 🔝 [Back to table of contents](#)
4692 
4693 SOAP literal versus encoding {#lit-enc}
4694 ----------------------------
4695 
4696 The `wsdl:operation/soap:body/@use` attribute in the <i>`<wsdl:binding>`</i> section
4697 of a WSDL is either "literal" or "encoded". The "encoded" use refers to the
4698 SOAP encoding rules that support id-ref multi-referenced elements to serialize
4699 data as graphs.
4700 
4701 SOAP encoding is very useful if the data internally forms a graph (including
4702 cycles) and we want the graph to be serialized in XML in a format that ensures
4703 that its structure is preserved. In that case, SOAP 1.2 encoding is the best
4704 option.
4705 
4706 SOAP encoding also adds encoding rules for [SOAP arrays](#toxsd10) to serialize
4707 multi-dimensional arrays. The use of XML attributes to exchange XML data in
4708 SOAP encoding is not permitted. The only attributes permitted are the standard
4709 XSD attributes, SOAP encoding attributes (such as for arrays), and id-ref.
4710 
4711 For example, the following directives in the interface header file for soapcpp2
4712 declare that `DBupdate` is a SOAP RPC encoding service method:
4713 
4714 ~~~{.cpp}
4715  //gsoap ns service namespace: urn:DB
4716  //gsoap ns service method-protocol: DBupdate SOAP
4717  //gsoap ns service method-style: DBupdate rpc
4718  //gsoap ns service method-encoding: DBupdate encoded
4719  int ns__DBupdate(...);
4720 ~~~
4721 
4722 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4723 an encodingStyle attribute for SOAP 1.1 encoding and an element representing the
4724 operation with parameters that are SOAP 1.1 encoded:
4725 
4726 <div class="alt">
4727 ~~~{.xml}
4728  <SOAP-ENV:Envelope
4729  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4730  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4731  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4732  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4733  xmlsn:ns="urn:DB">
4734  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4735  <ns:DBupdate>
4736  <records SOAP-ENC:arrayType="ns:record[3]">
4737  <item>
4738  <name href="#_1"/>
4739  <SSN>1234567890</SSN>
4740  </item>
4741  <item>
4742  <name>Jane</name>
4743  <SSN>1987654320</SSN>
4744  </item>
4745  <item>
4746  <name href="#_1"/>
4747  <SSN>2345678901</SSN>
4748  </item>
4749  </records>
4750  </ns:DBupdate>
4751  <id id="_1" xsi:type="xsd:string">Joe</id>
4752  </SOAP-ENV:Body>
4753  </SOAP-ENV:Envelope>
4754 ~~~
4755 </div>
4756 
4757 In the XML fragment shown above the name "Joe" is shared by two records and the
4758 string is referenced by SOAP 1.1 href and id attributes.
4759 
4760 While the soapcpp-generated serializers only introduce multi-referenced
4761 elements in the payload when they are actually multi-referenced in the data
4762 graph, other SOAP applications may render multi-referenced elements more
4763 aggressively. The example could also be rendered as:
4764 
4765 <div class="alt">
4766 ~~~{.xml}
4767  <SOAP-ENV:Envelope
4768  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4769  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4770  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4771  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4772  xmlsn:ns="urn:DB">
4773  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4774  <ns:DBupdate>
4775  <records SOAP-ENC:arrayType="ns:record[3]">
4776  <item href="#id1"/>
4777  <item href="#id2"/>
4778  <item href="#id3"/>
4779  </records>
4780  </ns:DBupdate>
4781  <id id="id1" xsi:type="ns:record">
4782  <name href="#id4"/>
4783  <SSN>1234567890</SSN>
4784  </id>
4785  <id id="id2" xsi:type="ns:record">
4786  <name href="#id5"/>
4787  <SSN>1987654320</SSN>
4788  </id>
4789  <id id="id3" xsi:type="ns:record">
4790  <name href="#id4"/>
4791  <SSN>2345678901</SSN>
4792  </id>
4793  <id id="id4" xsi:type="xsd:string">Joe</id>
4794  <id id="id5" xsi:type="xsd:string">Jane</id>
4795  </SOAP-ENV:Body>
4796  </SOAP-ENV:Envelope>
4797 ~~~
4798 </div>
4799 
4800 SOAP 1.2 encoding is cleaner and produces more accurate XML encodings of data
4801 graphs by setting the id attribute on the element that is referenced:
4802 
4803 <div class="alt">
4804 ~~~{.xml}
4805  <SOAP-ENV:Envelope
4806  xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope"
4807  xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding"
4808  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4809  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4810  xmlsn:ns="urn:DB">
4811  <SOAP-ENV:Body>
4812  <ns:DBupdate SOAP-ENV:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
4813  <records SOAP-ENC:itemType="ns:record" SOAP-ENC:arraySize="3">
4814  <item>
4815  <name SOAP-ENC:id="_1">Joe</name>
4816  <SSN>1234567890</SSN>
4817  </item>
4818  <item>
4819  <name>Jane</name>
4820  <SSN>1987654320</SSN>
4821  </item>
4822  <item>
4823  <name SOAP-ENC:ref="_1"/>
4824  <SSN>2345678901</SSN>
4825  </item>
4826  </records>
4827  </ns:DBupdate>
4828  </SOAP-ENV:Body>
4829  </SOAP-ENV:Envelope>
4830 ~~~
4831 </div>
4832 
4833 @note Some SOAP 1.2 applications consider the namespace `SOAP-ENC` of
4834 <i>`SOAP-ENC:id`</i> and <i>`SOAP-ENC:ref`</i> optional. With gSOAP, the SOAP
4835 1.2 encoding serialization follows the 2007 standard, while accepting
4836 unqualified id and ref attributes.
4837 
4838 To remove all rendered id-ref multi-referenced elements, use the
4839 `SOAP_XML_TREE` flag to initialize the `soap` context.
4840 
4841 Some XSD validation rules are turned off with SOAP encoding, because of the
4842 presence of additional attributes, such as id and ref/href, SOAP arrays with
4843 arbitrary element tags for array elements, and the occurrence of additional
4844 multi-ref elements in the SOAP 1.1 Body.
4845 
4846 The use of "literal" puts no restrictions on the XML in the SOAP Body. Full
4847 XSD validation is possible, which can be enabled with the `SOAP_XML_STRICT`
4848 flag to initialize the `soap` context. However, data graphs will be
4849 serialized as trees and cycles in the data will be cut from the XML rendition.
4850 
4851 🔝 [Back to table of contents](#)
4852 
4853 SOAP 1.1 versus SOAP 1.2 {#soap}
4854 ------------------------
4855 
4856 There are two SOAP protocol versions: 1.1 and 1.2. The gSOAP tools can switch
4857 between the two versions seamlessly. You can declare the default SOAP version
4858 for a service operation as follows:
4859 
4860 ~~~{.cpp}
4861  //gsoap ns service method-protocol: DBupdate SOAP1.2
4862 ~~~
4863 
4864 Use `SOAP` (SOAP 1.1), `SOAP1.1`, `SOAP1.2`, and `HTTP` to switch SOAP versions
4865 or enable REST methods with HTTP POST. See [service directives](#directives-1)
4866 and [XML serialization](#non-soap).
4867 
4868 The soapcpp2 tool auto-generates client and server code. At the client side,
4869 this operation sends data with SOAP 1.2 but accepts responses also in SOAP 1.1.
4870 At the server side, this operation accepts requests in SOAP 1.1 and 1.2 and
4871 will return responses in the same SOAP version.
4872 
4873 As we discussed in the previous section, the SOAP 1.2 protocol has a cleaner
4874 multi-referenced element serialization format that greatly enhances the
4875 accuracy of data graph serialization with SOAP RPC encoding and is therefore
4876 recommended.
4877 
4878 The SOAP 1.2 protocol default can also be set by importing and loading
4879 <i>`gsoap/import/soap12.h`</i>:
4880 
4881 ~~~{.cpp}
4882  #import "soap12.h"
4883 ~~~
4884 
4885 Finally, the soapcpp2 tool has options to force SOAP 1.1, SOAP 1.2, or remove
4886 SOAP altogether with <b>`soapcpp2 -1`</b> (SOAP 1.1), <b>`soapcpp2 -2`</b>
4887 (SOAP 1.2) and <b>`soapcpp2 -0`</b> (plain XML, no SOAP).
4888 
4889 🔝 [Back to table of contents](#)
4890 
4891 XML serialization {#non-soap}
4892 -----------------
4893 
4894 You can serialize data to XML that is stored on the heap, on the stack (locals), and
4895 static data as long as the serializable (i.e. non-transient) values are
4896 properly initialized and pointers in the data structures are either NULL or
4897 point to valid structures.
4898 
4899 When XML is deserialized into data, the data is put on the heap and managed by the
4900 `::soap` context, see also [memory management](#memory).
4901 
4902 You can read and write XML directly to a file or stream with the serializing
4903 [operations on classes and structs](#toxsd9-14).
4904 
4905 To define and use XML Web service client and service operations, we can declare
4906 these operations in your interface header file with the data binding interface
4907 for soapcpp2 as functions. The function are translated by soapcpp2 to
4908 client-side service invocation calls and server-side service operation
4909 dispatchers.
4910 
4911 The REST operations POST, GET, and PUT are declared with `//gsoap` directives
4912 in the interface header file for soapcpp2. For example, a REST HTTP POST
4913 operation is declared as follows:
4914 
4915 ~~~{.cpp}
4916  //gsoap ns service namespace: urn:DB
4917  //gsoap ns service method-protocol: DBupdate POST
4918  int ns__DBupdate(...);
4919 ~~~
4920 
4921 There are no SOAP Envelope and SOAP Body elements in the payload for
4922 `DBupdate`. Also the XML serialization rules are identical to SOAP
4923 document/literal, meaning no SOAP RPC encoding XML structures are implicitly
4924 used. The XML payload only has the operation name as an element with its
4925 parameters serialized as subelements:
4926 
4927 <div class="alt">
4928 ~~~{.xml}
4929  <ns:DBupdate xmln:ns="urn:DB" ...>
4930  ...
4931  </ns:DBupdate>
4932 ~~~
4933 </div>
4934 
4935 To force id-ref serialization with REST similar to SOAP 1.2 multi-reference
4936 encoding, use the `SOAP_XML_GRAPH` flag to initialize the `soap` context.
4937 The XML serialization includes id and ref attributes for multi-referenced
4938 elements as follows:
4939 
4940 <div class="alt">
4941 ~~~{.xml}
4942  <ns:DBupdate xmln:ns="urn:DB" ...>
4943  <records>
4944  <item>
4945  <name id="_1">Joe</name>
4946  <SSN>1234567890</SSN>
4947  </item>
4948  <item>
4949  <name>Jane</name>
4950  <SSN>1987654320</SSN>
4951  </item>
4952  <item>
4953  <name ref="_1"/>
4954  <SSN>2345678901</SSN>
4955  </item>
4956  </records>
4957  </ns:DBupdate>
4958 ~~~
4959 </div>
4960 
4961 🔝 [Back to table of contents](#)
4962 
4963 Input and output {#io}
4964 ================
4965 
4966 Reading and writing XML from/to files, streams and string buffers is done via
4967 the managing `soap` context by setting one of the following context variables that
4968 control IO sources and sinks:
4969 
4970 ~~~{.cpp}
4971  soap->recvfd = fd; // an int file descriptor to read from (0 by default)
4972  soap->sendfd = fd; // an int file descriptor to write to (1 by default)
4973  soap->is = &is; // C++ only: a std::istream is object to read from
4974  soap->os = &os; // C++ only: a std::ostream os object to write to
4975  soap->is = cs; // C only: a const char* string to read from (soap->is will advance)
4976  soap->os = &cs; // C only: pointer to a const char*, will be set to point to the string output
4977 ~~~
4978 
4979 Normally, all of these context variables are NULL, which is required to send and
4980 receive data over sockets by gSOAP client and server applications. Therefore,
4981 if you set any of these context variables in a client or server application
4982 then you should reset them to NULL to ensure that socket communications are not
4983 blocked.
4984 
4985 @note The use of `soap::is` and `soap::os` in C requires gSOAP 2.8.28 or greater.
4986 
4987 In the following sections, we present more details on how to read and write to
4988 files and streams, and use string buffers as sources and sinks for XML data.
4989 
4990 In addition, you can set IO callback functions to handle IO at a lower level.
4991 For more details on defining your own callback functions, see the
4992 [gSOAP user guide.](../../guide/html/index.html)
4993 
4994 🔝 [Back to table of contents](#)
4995 
4996 Reading and writing from/to files and streams {#io1}
4997 ---------------------------------------------
4998 
4999 The default IO is standard input and output. Other sources and sinks (those
5000 listed above) will be used until you (re)set them. For example with file-based
5001 input and output:
5002 
5003 ~~~{.cpp}
5004  FILE *fp = fopen("record.xml", "r");
5005  if (fp != NULL)
5006  {
5007  soap->recvfd = fileno(fp); // get file descriptor of file to read from
5008  if (soap_read_ns__record(soap, &pers1))
5009  ... // handle IO error
5010  fclose(fp);
5011  soap->recvfd = 0; // read from stdin, or -1 to block reading
5012  }
5013 
5014  FILE *fp = fopen("record.xml", "w");
5015  if (fp != NULL)
5016  {
5017  soap->sendfd = fileno(fp); // get file descriptor of file to write to
5018  if (soap_write_ns__record(soap, &pers1))
5019  ... // handle IO error
5020  fclose(fp);
5021  soap->sendfd = 1; // write to stdout, or -1 to block writing
5022  }
5023 ~~~
5024 
5025 Similar code with streams in C++:
5026 
5027 ~~~{.cpp}
5028  #include <fstream>
5029 
5030  std::fstream fs;
5031  fs.open("record.xml", std::ios::in);
5032  if (fs)
5033  {
5034  soap->is = &fs;
5035  if (soap_read__ns__record(soap, &pers1))
5036  ... // handle IO error
5037  fs.close();
5038  soap->is = NULL;
5039  }
5040 
5041  fs.open("record.xml", std::ios::out);
5042  if (fs)
5043  {
5044  soap->os = &fs;
5045  if (soap_write__ns__record(soap, &pers1))
5046  ... // handle IO error
5047  fs.close();
5048  soap->os = NULL;
5049  }
5050 ~~~
5051 
5052 🔝 [Back to table of contents](#)
5053 
5054 Reading and writing from/to string buffers {#io2}
5055 ------------------------------------------
5056 
5057 For C++ we recommend to use `std::stringstream` objects from the
5058 <i>`sstream`</i> C++ library as illustrated in the following example:
5059 
5060 ~~~{.cpp}
5061  #include <sstream>
5062 
5063  std::stringstream ss;
5064  ss.str("..."); // XML to parse
5065  soap->is = &ss;
5066  if (soap_read__ns__record(soap, &pers1))
5067  ... // handle IO error
5068  soap->is = NULL;
5069 
5070  soap->os = &ss;
5071  if (soap_write__ns__record(soap, &pers1))
5072  ... // handle IO error
5073  soap->os = NULL;
5074  std::string s = ss.str(); // string with XML
5075 ~~~
5076 
5077 For C we can use `soap::is` and `soap::os` to point to strings of XML content
5078 as follows (this requires gSOAP 2.8.28 or later):
5079 
5080 ~~~{.cpp}
5081  soap->is = "..."; // XML to parse
5082  if (soap_read__ns__record(soap, &pers1))
5083  ... // handle IO error
5084  soap->is = NULL;
5085 
5086  const char *cs = NULL;
5087  soap->os = &cs;
5088  if (soap_write__ns__record(soap, &pers1))
5089  ... // handle IO error
5090  soap->os = NULL;
5091  ... = cs; // string with XML (do not free(cs): managed by the context and freed with soap_end())
5092 ~~~
5093 
5094 The type of `soap::os` is a pointer to a `const char*` string. The pointer is
5095 set by the managing `soap` context to point to the XML data that is stored on
5096 the context-managed heap.
5097 
5098 For earlier gSOAP versions we recommend to use IO callbacks `soap::frecv` and
5099 `soap::fsend`, see the [gSOAP user guide.](../../guide/html/index.html).
5100 
5101 🔝 [Back to table of contents](#)
5102 
5103 Memory management {#memory}
5104 =================
5105 
5106 Memory management with the `soap` context enables us to allocate data in
5107 context-managed heap space that can be collectively deleted. All deserialized
5108 data is placed on the context-managed heap by the `soap` context of the engine.
5109 
5110 🔝 [Back to table of contents](#)
5111 
5112 Memory management in C {#memory1}
5113 ----------------------
5114 
5115 When working with gSOAP in C (i.e. using <b>`wsdl2h -c`</b> option <b>`-c`</b>
5116 or <b>`soapcpp2 -c`</b> option <b>`-c`</b>), data is allocated on the managed heap with:
5117 
5118 - `void *soap_malloc(struct soap*, size_t len)`.
5119 
5120 This function allocates `len` bytes on the heap managed by the specified
5121 context and returns NULL when allocation failed.
5122 
5123 You can also make shallow copies of data with `soap_memdup` that uses
5124 `soap_malloc` and a safe version of `memcpy` to copy a chunk of data `src` with
5125 length `len` to the context-managed heap:
5126 
5127 - `void * soap_memdup(struct soap*, const void *src, size_t len)`
5128 
5129 This function returns a pointer to the copy. This function requires gSOAP
5130 2.8.27 or later.
5131 
5132 In gSOAP 2.8.35 and greater versions, you can use an auto-generated function to
5133 allocate and initialize data of type `T` on the managed heap:
5134 
5135 - `T * soap_new_T(struct soap*, int n)`
5136 
5137 This function returns an array of length `n` of type `T` data that is default
5138 initialized (by internally calling `soap_malloc(soap, n * sizeof(T))` and then
5139 `soap_default_T(soap, T*)` on each array value). Use a negative value or `n=1`
5140 to allocate and initialize a single value. This function returns NULL when
5141 allocation failed.
5142 
5143 The `soap_malloc` function is essentially a wrapper around `malloc`, but
5144 permits the `soap` context to track all heap allocations for collective
5145 deletion with `soap_end(soap)`:
5146 
5147 ~~~{.cpp}
5148  #include "soapH.h"
5149  #include "ns.nsmap"
5150  ...
5151  struct soap *soap = soap_new(); // new context
5152  ...
5153  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5154  soap_default_ns__record(soap, record); // auto-generated struct initializer
5155  ...
5156  soap_destroy(soap); // only for C++, see section on C++ below
5157  soap_end(soap); // delete record and all other heap allocations
5158  soap_free(soap); // delete context
5159 ~~~
5160 
5161 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5162 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5163 the `soap` context and free the context, respectively. Use
5164 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5165 `soap_done(soap)` only when the context is stack allocated (so cannot be
5166 deleted from the heap).
5167 
5168 The managed heap is checked for memory leaks at run time when the source code
5169 is compiled with option <b>`-DDEBUG`</b>.
5170 
5171 The soapcpp2 auto-generated deserializers in C use `soap_malloc` to allocate
5172 and populate deserialized structures, which are managed by the context for
5173 collective deletion.
5174 
5175 To make `char*` and `wchar_t*` string copies to the context-managed heap, we
5176 can use the functions:
5177 
5178 - `char *soap_strdup(struct soap*, const char *str)` and
5179 
5180 - `wchar_t *soap_wstrdup(struct soap*, const wchar_t *wstr)`.
5181 
5182 If your C compiler supports `typeof` then you can use the following macro to
5183 simplify the managed heap allocation and initialization of primitive values:
5184 
5185 ~~~{.cpp}
5186  #define soap_assign(soap, lhs, rhs) (*(lhs = (typeof(lhs))soap_malloc(soap, sizeof(*lhs))) = rhs)
5187 ~~~
5188 
5189 Pointers to primitive values are often used for optional members. For example,
5190 assume we have the following struct:
5191 
5192 ~~~{.cpp}
5193  struct ns__record
5194  {
5195  const char *name 1; // required (minOccurs=1)
5196  uint64_t *SSN; // optional (pointer means minOccurs=0)
5197  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5198  };
5199 ~~~
5200 
5201 Use `soap_assign` to create a SSN value on the managed heap:
5202 
5203 ~~~{.cpp}
5204  struct soap *soap = soap_new(); // new context
5205  ...
5206  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5207  soap_default_ns__record(soap, record);
5208  record->name = soap_strdup(soap, "Joe");
5209  soap_assign(soap, record->SSN, 1234567890UL);
5210  ...
5211  soap_end(soap); // delete managed soap_malloc'ed heap data
5212  soap_free(soap); // delete context
5213 ~~~
5214 
5215 Without the `soap_assign` macro, you will need two lines of code, one to
5216 allocate and one to assign (you should also use this if your system can run out
5217 of memory):
5218 
5219 ~~~{.cpp}
5220  assert((record->SSN = (uint64_t*)soap_malloc(soap, sizeof(utint64_t))) != NULL);
5221  *record->SSN = 1234567890UL;
5222 ~~~
5223 
5224 The serializer can serialize any heap, stack, or static allocated data. So we
5225 can also create a new record as follows:
5226 
5227 ~~~{.cpp}
5228  struct soap *soap = soap_new(); // new context
5229  ...
5230  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5231  static uint64_t SSN = 1234567890UL;
5232  soap_default_ns__record(soap, record);
5233  record->name = "Joe";
5234  record->SSN = &SSN; // safe to use static values: the value of record->SSN is never changed
5235  ...
5236  soap_end(soap); // delete managed soap_malloc'ed heap data
5237  soap_free(soap); // delete context
5238 ~~~
5239 
5240 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5241 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to
5242 generate), here shown for C with the second argument `dst` NULL because we want
5243 to allocate a new managed structure:
5244 
5245 ~~~{.cpp}
5246  struct soap *other_soap = soap_new(); // another context
5247  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5248  ...
5249  soap_destroy(other_soap); // only for C++, see section on C++ below
5250  soap_end(other_soap); // delete other_record and all of its deep data
5251  soap_free(other_soap); // delete context
5252 ~~~
5253 
5254 The only reason to use another `soap` context and not to use the primary `soap`
5255 context is when the primary context must be destroyed together with all of the
5256 objects it manages while some of the objects must be kept alive. If the
5257 objects that are kept alive contain deep cycles then this is the only option we
5258 have, because deep copy with a managing `soap` context detects and preserves
5259 these cycles unless the `SOAP_XML_TREE` flag is used with the `soap` context:
5260 
5261 ~~~{.cpp}
5262  struct soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5263  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5264 ~~~
5265 
5266 The resulting deep copy will be a full copy of the source data structure as a
5267 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5268 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5269 
5270 You can also deep copy into unmanaged space and use the auto-generated
5271 `soap_del_T()` function (requires <b>`soapcpp2 -Ed`</b> option <b>`-Ed`</b> to generate) to delete
5272 it later:
5273 
5274 ~~~{.cpp}
5275  struct ns__record *other_record = soap_dup_ns__record(NULL, NULL, record);
5276  ...
5277  soap_del_ns__record(other_record); // deep delete record data members
5278  free(other_record); // delete the record
5279 ~~~
5280 
5281 But you should not do this for any data that has deep cycles in its runtime
5282 data structure. Cycles in the data structure will lead to non-termination when
5283 making unmanaged deep copies. Consider for example:
5284 
5285 ~~~{.cpp}
5286  struct ns__record
5287  {
5288  const char *name 1; // required (minOccurs=1)
5289  uint64_t SSN; // required (non-pointer means minOccurs=1)
5290  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5291  };
5292 ~~~
5293 
5294 The code to populate a structure with a mutual spouse relationship:
5295 
5296 ~~~{.cpp}
5297  struct soap *soap = soap_new();
5298  ...
5299  struct ns__record pers1, pers2;
5300  soap_default_ns__record(soap, &pers1);
5301  soap_default_ns__record(soap, &pers2);
5302  pers1.name = "Joe"; // OK to serialize static data
5303  pers1.SSN = 1234567890;
5304  pers1.spouse = &pers2;
5305  pers2.name = soap_strdup(soap, "Jane"); // allocates and copies a string
5306  pers2.SSN = 1987654320;
5307  pers2.spouse = &pers1;
5308  ...
5309  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5310  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5311  soap_set_mode(soap, SOAP_XML_TREE);
5312  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5313 ~~~
5314 
5315 The bad case is where there is no context used in the first argument. The deep
5316 copy functions use a context to keep track of co-referenced data nodes and
5317 cycles in the data structure copies, to copy co-referenced nodes just once.
5318 Co-references in a data structure are formed by pointers and smart pointers
5319 such as `std::shared_ptr`, such that at least two pointers point to the same
5320 data.
5321 
5322 The serializer can serialize any heap, stack, or static allocated data, such as
5323 in the code shown above. So we can serialize the stack-allocated `pers1`
5324 record as follows:
5325 
5326 ~~~{.cpp}
5327  FILE *fp = fopen("record.xml", "w");
5328  if (fp != NULL)
5329  {
5330  soap->sendfd = fileno(fp); // file descriptor to write to
5331  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5332  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5333  soap_write_ns__record(soap, &pers1);
5334  fclose(fp);
5335  soap->sendfd = -1; // block further writing
5336  }
5337 ~~~
5338 
5339 which produces an XML document record.xml that is similar to:
5340 
5341 <div class="alt">
5342 ~~~{.xml}
5343  <ns:record xmlns:ns="urn:types" id="Joe">
5344  <name>Joe</name>
5345  <SSN>1234567890</SSN>
5346  <spouse id="Jane">
5347  <name>Jane</name>
5348  <SSN>1987654320</SSN>
5349  <spouse ref="#Joe"/>
5350  </spouse>
5351  </ns:record>
5352 ~~~
5353 </div>
5354 
5355 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5356 leads to the same non-termination problem when we later try to copy the data
5357 into unmanaged memory heap space:
5358 
5359 ~~~{.cpp}
5360  struct soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5361  ...
5362  struct ns__record pers1;
5363  FILE *fp = fopen("record.xml", "r");
5364  if (fp != NULL)
5365  {
5366  soap->recvfd = fileno(fp);
5367  if (soap_read_ns__record(soap, &pers1))
5368  ... // handle IO error
5369  fclose(fp);
5370  soap->recvfd = -1; // blocks further reading
5371  }
5372  ...
5373  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5374  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5375  soap_set_mode(soap, SOAP_XML_TREE);
5376  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5377 ~~~
5378 
5379 Copying data with `soap_dup_T(soap)` into managed heap memory space is always
5380 safe. Copying into unmanaged heap memory space requires diligence. But
5381 deleting unmanaged data is easy with `soap_del_T()`.
5382 
5383 You can also use `soap_del_T()` to delete structures that you created in C, but
5384 only if these structures are created with `malloc` and do NOT contain pointers
5385 to stack and static data.
5386 
5387 You can unlink one or more allocated objects from the managed heap to allow the
5388 object to live after `soap_end(soap)` by using:
5389 
5390 - `void soap_unlink(struct soap *soap, void *ptr)`
5391 
5392 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5393 `soap_end(soap)`. Do not forget to free the data with `free(ptr)`. Be aware
5394 that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If `ptr` is a
5395 struct, pointer members will become invalid when pointing to objects on the
5396 managed heap. Use `soap_unlink(soap, ptr->member)` to unlink `member` as well.
5397 
5398 Finally, when data is allocated in managed memory heap space, either explicitly
5399 with the allocation functions shown above or by the soapcpp2-generated
5400 deserializers, you can delegate the management and deletion of this data to
5401 another `soap` context. That context will be responsible to delete the data
5402 with `soap_end(soap)` later:
5403 
5404 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5405 
5406 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5407 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5408 `soap_from` is stack-allocated) while the managed data remains intact. You
5409 can use this function any time, to delegate management and deletion to another
5410 context `soap_to` and then continue with the current context. You can also use
5411 different source `soap_from` contexts to delegate management and deletion to
5412 the other `soap_to` context. To mass delete all managed data, use
5413 `soap_end(soap_to)`.
5414 
5415 🔝 [Back to table of contents](#)
5416 
5417 Memory management in C++ {#memory2}
5418 ------------------------
5419 
5420 When working with gSOAP in C++, the engine allocates data on a managed heap
5421 using `soap_new_T(soap)` to allocate a type with type name `T`. Managed heap
5422 allocation is tracked by the `soap` context for collective deletion with
5423 `soap_destroy(soap)` for structs, classes, and templates and with
5424 `soap_end(soap)` for everything else.
5425 
5426 You should only use `soap_malloc(struct soap*, size_t len)` to allocate
5427 primitive types because constructors are not invoked. Therefore, `soap_new_T`
5428 is preferred. The auto-generated `T * soap_new_T(struct soap*)` returns data
5429 allocated on the managed heap for type `T`. The data is mass-deleted with
5430 `soap_destroy(soap)` followed by `soap_end(soap)`.
5431 
5432 The `soap_new_T` functions return NULL when allocation fails. C++ exceptions
5433 are never raised by the engine and serializers when data is allocated.
5434 
5435 There are four variations of `soap_new_T` functions to allocate data of type
5436 `T` that soapcpp2 auto-generates:
5437 
5438 - `T * soap_new_T(struct soap*)` returns a new instance of `T` that is default
5439  initialized. For classes, initialization is internally performed using the
5440  soapcpp2 auto-generated `void T::soap_default(struct soap*)` method of the
5441  class, but ONLY IF the soapcpp2 auto-generated default constructor is used
5442  that invokes `soap_default()` and was not replaced by a user-defined default
5443  constructor.
5444 
5445 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
5446  `T`. The instances in the array are default initialized as described above.
5447 
5448 - `T * soap_new_req_T(struct soap*, ...)` (structs and classes only) returns a
5449  new instance of `T` and sets the required data members to the values
5450  specified in `...`. The required data members are those with nonzero
5451  minOccurs, see the subsections on
5452  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
5453  [container and array members and their occurrence constraints](#toxsd9-9).
5454 
5455 - `T * soap_new_set_T(struct soap*, ...)` (structs and classes only) returns a
5456  new instance of `T` and sets the public/serializable data members to the values
5457  specified in `...`.
5458 
5459 The above functions can be invoked with a NULL `soap` context, but you are then
5460 responsible to use `delete T` to remove this instance from the unmanaged heap.
5461 
5462 For example, to allocate a managed `std::string` you can use:
5463 
5464 ~~~{.cpp}
5465  std::string *s = soap_new_std__string(soap);
5466 ~~~
5467 
5468 To throw a `std::bad_alloc` exception when memory allocation fails, we can define the
5469 following class and macro:
5470 
5471 ~~~{.cpp}
5472  class alloc_check {
5473  public:
5474  alloc_check()
5475  { }
5476  template<typename T>
5477  T operator=(T ptr)
5478  {
5479  if (ptr == NULL)
5480  throw std::bad_alloc();
5481  return ptr;
5482  }
5483  };
5484 
5485  #define CHECK alloc_check() =
5486 ~~~
5487 
5488 And use `CHECK` as follows to throw an exception when memory allocation fails:
5489 
5490 ~~~{.cpp}
5491  std::string *s = CHECK soap_new_std__string(soap);
5492 ~~~
5493 
5494 To throw a `std::runtime_exception` when memory allocation fails, with file
5495 and line number information where the error occurred, we can define the
5496 following revised version of our exception-throwing macro:
5497 
5498 ~~~{.cpp}
5499  class alloc_failure : public std::runtime_error {
5500  public:
5501  alloc_failure(const char *file, size_t line) : std::runtime_error(error(file, line))
5502  { }
5503  private:
5504  std::string error(const char *file, size_t line) const
5505  {
5506  std::stringstream ss;
5507  ss << "Memory allocation failed in " << file << " at line " << line;
5508  return ss.str();
5509  }
5510  };
5511 
5512  class alloc_check_with_info {
5513  public:
5514  alloc_check_with_info(const char *file, size_t line) : file(file), line(line)
5515  { }
5516  template<typename T>
5517  T operator=(T ptr) const
5518  {
5519  if (ptr == NULL)
5520  throw alloc_failure(file, line);
5521  return ptr;
5522  }
5523  const char *file;
5524  size_t line;
5525  };
5526 
5527  #define CHECK alloc_check_with_info(__FILE__, __LINE__) =
5528 ~~~
5529 
5530 And use `CHECK` as follows to throw an exception with the file and line number
5531 of the location where memory allocation failed:
5532 
5533 ~~~{.cpp}
5534  std::string *s = CHECK soap_new_std__string(soap);
5535 ~~~
5536 
5537 Primitive types and arrays of primitive values may be allocated with
5538 `soap_malloc` (actually, `soap_new_T` calls `soap_malloc` for primitive type
5539 `T`). All primitive types (i.e. no classes, structs, class templates,
5540 containers, and smart pointers) are allocated with `soap_malloc` for reasons of
5541 efficiency.
5542 
5543 You can use a C++ template to simplify the managed allocation and initialization
5544 of primitive values as follows (this is for primitive types only):
5545 
5546 ~~~{.cpp}
5547  template<class T>
5548  T * soap_make(struct soap *soap, T val)
5549  {
5550  T *p = (T*)soap_malloc(soap, sizeof(T));
5551  if (p == NULL)
5552  throw std::bad_alloc();
5553  *p = val;
5554  return p;
5555  }
5556 ~~~
5557 
5558 For example, assuming we have the following class:
5559 
5560 ~~~{.cpp}
5561  class ns__record
5562  { public:
5563  std::string name; // required (non-pointer means minOccurs=1)
5564  uint64_t *SSN; // optional (pointer means minOccurs=0)
5565  ns__record *spouse; // optional (pointer means minOccurs=0)
5566  };
5567 ~~~
5568 
5569 You can instantiate a record by using the auto-generated
5570 `soap_new_set_ns__record` and use `soap_make` to create a SSN value on the
5571 managed heap as follows:
5572 
5573 ~~~{.cpp}
5574  soap *soap = soap_new(); // new context
5575  ...
5576  ns__record *record = soap_new_set_ns__record(
5577  soap,
5578  "Joe",
5579  soap_make<uint64_t>(soap, 1234567890UL),
5580  NULL);
5581  ...
5582  soap_destroy(soap); // delete record and all other managed instances
5583  soap_end(soap); // delete managed soap_malloc'ed heap data
5584  soap_free(soap); // delete context
5585 ~~~
5586 
5587 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5588 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5589 the `soap` context and free the context, respectively. Use
5590 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5591 `soap_done(soap)` only when the context is stack allocated (so cannot be
5592 deleted from the heap).
5593 
5594 The managed heap is checked for memory leaks at run time when the source code
5595 is compiled with option <b>`-DDEBUG`</b>.
5596 
5597 However, the serializer can serialize any heap, stack, or static allocated
5598 data. So we can also create a new record as follows:
5599 
5600 ~~~{.cpp}
5601  uint64_t SSN = 1234567890UL;
5602  ns__record *record = soap_new_set_ns__record(soap, "Joe", &SSN, NULL);
5603 ~~~
5604 
5605 which will be fine to serialize this record as long as the local `SSN`
5606 stack-allocated value remains in scope when invoking the serializer and/or
5607 using `record`. It does not matter if `soap_destroy` and `soap_end` are called
5608 beyond the scope of `SSN`.
5609 
5610 To facilitate class methods to access the managing context, we can add a soap
5611 context pointer to a class/struct:
5612 
5613 ~~~{.cpp}
5614  class ns__record
5615  { public:
5616  ...
5617  void create_more(); // needs a context to create more internal data
5618  protected:
5619  struct soap *soap; // the context that manages this instance, or NULL
5620  };
5621 ~~~
5622 
5623 The `soap` context pointer member of the class is set when invoking
5624 `soap_new_T` (and similar) with a non-NULL context argument that will be
5625 assigned to the `soap` member of the class.
5626 
5627 You can also use a template when an array of pointers to values is required.
5628 To create an array of pointers to values, define the following template:
5629 
5630 ~~~{.cpp}
5631  template<class T>
5632  T **soap_make_array(struct soap *soap, T* array, int n) throw (std::bad_alloc)
5633  {
5634  T **p = (T**)soap_malloc(soap, n * sizeof(T*));
5635  if (p == NULL)
5636  throw std::bad_alloc();
5637  for (int i = 0; i < n; ++i)
5638  p[i] = &array[i];
5639  return p;
5640  }
5641 ~~~
5642 
5643 The `array` parameter is a pointer to an array of `n` values. The template
5644 returns an array of `n` pointers that point to the values in that array:
5645 
5646 ~~~{.cpp}
5647  // create an array of 100 pointers to 100 records
5648  int n = 100;
5649  ns__record **precords = soap_make_array(soap, soap_new_ns__record(soap, n), n);
5650  for (int i = 0; i < n; ++i)
5651  {
5652  precords[i]->name = "...";
5653  precords[i]->SSN = soap_make<uint64_t>(1234567890UL + i);
5654  }
5655 ~~~
5656 
5657 Note that `soap_new_ns__record(soap, n)` returns a pointer to an array of `n`
5658 records, which is then used to create an array of `n` pointers to these records.
5659 
5660 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5661 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate), here shown
5662 for C++ with the second argument `dst` NULL to allocate a new managed object:
5663 
5664 ~~~{.cpp}
5665  soap *other_soap = soap_new(); // another context
5666  ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5667  ...
5668  soap_destroy(other_soap); // delete record and other managed instances
5669  soap_end(other_soap); // delete other data (the SSNs on the heap)
5670  soap_free(other_soap); // delete context
5671 ~~~
5672 
5673 To duplicate base and derived instances when a base class pointer or reference
5674 is provided, use the auto-generated method `T * T::soap_dup(struct soap*)`:
5675 
5676 ~~~{.cpp}
5677  soap *other_soap = soap_new(); // another context
5678  ns__record *other_record = record->soap_dup(other_soap);
5679  ...
5680  soap_destroy(other_soap); // delete record and other managed instances
5681  soap_end(other_soap); // delete other data (the SSNs on the heap)
5682  soap_free(other_soap); // delete context
5683 ~~~
5684 
5685 The only reason to use another context and not to use the primary `soap`
5686 context is when the primary context must be destroyed together with all of the
5687 objects it manages while some of the objects must be kept alive. If the
5688 objects that are kept alive contain deep cycles then this is the only option we
5689 have, because deep copy with a managing `soap` context detects and preserves
5690 these cycles unless the `SOAP_XML_TREE` flag is used with the context:
5691 
5692 ~~~{.cpp}
5693  soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5694  ns__record *other_record = record->soap_dup(other_soap); // deep tree copy
5695 ~~~
5696 
5697 The resulting deep copy will be a full copy of the source data structure as a
5698 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5699 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5700 
5701 You can also deep copy into unmanaged space and use the auto-generated
5702 `soap_del_T()` function or the `T::soap_del()` method (requires
5703 <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate) to delete it later,
5704 but we should not do this for any data that has deep cycles in its runtime data
5705 structure graph:
5706 
5707 ~~~{.cpp}
5708  ns__record *other_record = record->soap_dup(NULL);
5709  ...
5710  other_record->soap_del(); // deep delete record data members
5711  delete other_record; // delete the record
5712 ~~~
5713 
5714 Cycles in the data structure will lead to non-termination when making unmanaged
5715 deep copies. Consider for example:
5716 
5717 ~~~{.cpp}
5718  class ns__record
5719  { public:
5720  const char *name 1; // required (minOccurs=1)
5721  uint64_t SSN; // required (non-pointer means minOccurs=1)
5722  ns__record *spouse; // optional (pointer means minOccurs=1)
5723  };
5724 ~~~
5725 
5726 The code to populate a structure with a mutual spouse relationship:
5727 
5728 ~~~{.cpp}
5729  soap *soap = soap_new();
5730  ...
5731  ns__record pers1, pers2;
5732  pers1.name = "Joe";
5733  pers1.SSN = 1234567890;
5734  pers1.spouse = &pers2;
5735  pers2.name = "Jane";
5736  pers2.SSN = 1987654320;
5737  pers2.spouse = &pers1;
5738  ...
5739  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5740  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5741  soap_set_mode(soap, SOAP_XML_TREE);
5742  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5743 ~~~
5744 
5745 The serializer can serialize any heap, stack, or static allocated data, such as
5746 shown in the code shown above. So we can serialize the stack-allocated `pers1`
5747 record as follows:
5748 
5749 ~~~{.cpp}
5750  FILE *fp = fopen("record.xml", "w");
5751  if (fp != NULL)
5752  {
5753  soap->sendfd = fileno(fp); // file descriptor to write to
5754  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5755  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5756  if (soap_write_ns__record(soap, &pers1))
5757  ... // handle IO error
5758  fclose(fp);
5759  soap->sendfd = -1; // block further writing
5760  }
5761 ~~~
5762 
5763 which produces an XML document record.xml that is similar to:
5764 
5765 <div class="alt">
5766 ~~~{.xml}
5767  <ns:record xmlns:ns="urn:types" id="Joe">
5768  <name>Joe</name>
5769  <SSN>1234567890</SSN>
5770  <spouse id="Jane">
5771  <name>Jane</name>
5772  <SSN>1987654320</SSN>
5773  <spouse ref="#Joe"/>
5774  </spouse>
5775  </ns:record>
5776 ~~~
5777 </div>
5778 
5779 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5780 leads to the same non-termination problem when we later try to copy the data
5781 into unmanaged space:
5782 
5783 ~~~{.cpp}
5784  soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5785  ...
5786  ns__record pers1;
5787  FILE *fp = fopen("record.xml", "r");
5788  if (fp != NULL)
5789  {
5790  soap->recvfd = fileno(fp); // file descriptor to read from
5791  if (soap_read_ns__record(soap, &pers1))
5792  ... // handle IO error
5793  fclose(fp);
5794  soap->recvfd = -1; // block further reading
5795  }
5796  ...
5797  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5798  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5799  soap_set_mode(soap, SOAP_XML_TREE);
5800  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5801 ~~~
5802 
5803 Copying data with `soap_dup_T(soap)` into managed space is always safe. Copying
5804 into unmanaged space requires diligence. But deleting unmanaged data is easy
5805 with `soap_del_T()`.
5806 
5807 You can also use `soap_del_T()` to delete structures in C++, but only if these
5808 structures are created with `new` (and `new []` for arrays when applicable) for
5809 classes, structs, and class templates and with `malloc` for anything else, and
5810 the structures do NOT contain pointers to stack and static data.
5811 
5812 You can unlink one or more allocated objects from the managed heap to allow the
5813 object to live after `soap_destroy(soap)` and `soap_end(soap)` by using:
5814 
5815 - `void soap_unlink(struct soap *soap, void *ptr)`
5816 
5817 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5818 `soap_destroy(soap)` and `soap_end(soap)`. Do not forget to free the data with
5819 `delete ptr` (C++ class instance only) or with `free(ptr)` (non-class data).
5820 Be aware that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If
5821 `ptr` is a struct or class, pointer members will become invalid when pointing
5822 to objects on the managed heap. Use `soap_unlink(soap, ptr->member)` to unlink
5823 `member` as well.
5824 
5825 Finally, when data is allocated in managed memory heap space, either explicitly
5826 with the allocation functions shown above or by the soapcpp2-generated
5827 deserializers, you can delegate the management and deletion of this data to
5828 another `soap` context. That context will be responsible to delete the data
5829 with `soap_destroy(soap)` and `soap_end(soap)` later:
5830 
5831 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5832 
5833 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5834 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5835 `soap_from` is stack-allocated) while the managed data remains intact. You
5836 can use this function any time, to delegate management and deletion to another
5837 context `soap_to` and then continue with the current context. You can also use
5838 different source `soap_from` contexts to delegate management and deletion to
5839 the other `soap_to` context. To mass delete all managed data, use
5840 `soap_destroy(soap_to)` followed by `soap_end(soap_to)`.
5841 
5842 🔝 [Back to table of contents](#)
5843 
5844 Context flags to initialize the soap struct {#flags}
5845 ===========================================
5846 
5847 There are several `soap` context initialization flags and context mode flags to
5848 control XML serialization at runtime. The flags are set with `soap_new1()` to
5849 allocate and initialize a new context:
5850 
5851 ~~~{.cpp}
5852  struct soap *soap = soap_new1(flag1 | flag2 | ... | flagn);
5853  ...
5854  soap_destroy(soap); // delete objects
5855  soap_end(soap); // delete other data and temp data
5856  soap_free(soap); // free context
5857 ~~~
5858 
5859 and with `soap_init1()` for stack-allocated contexts:
5860 
5861 ~~~{.cpp}
5862  struct soap soap;
5863  soap_init1(&soap, flag1 | flag2 | ... | flagn);
5864  ...
5865  soap_destroy(&soap); // delete objects
5866  soap_end(&soap); // delete other data and temp data
5867  soap_done(&soap); // clear context
5868 ~~~
5869 
5870 where `flag1`, `flag2`, ..., `flagn` is one of:
5871 
5872 - `SOAP_C_UTFSTRING`: enables all `std::string` and `char*` strings to
5873  contain UTF-8 content. This option is recommended.
5874 
5875 - `SOAP_C_NILSTRING`: treat empty strings as if they were NULL pointers, i.e.
5876  omits elements and attributes when empty.
5877 
5878 - `SOAP_XML_STRICT`: strictly validates XML while deserializing. Should not be
5879  used together with SOAP 1.1/1.2 encoding style of messaging. Use
5880  <b>`soapcpp2 -s`</b> option <b>`-s`</b> to hard code `SOAP_XML_STRICT` in the
5881  generated serializers. Not recommended with SOAP 1.1/1.2 encoding style
5882  messaging.
5883 
5884 - `SOAP_XML_INDENT`: produces indented XML.
5885 
5886 - `SOAP_XML_CANONICAL`: c14n canonocalization, removes unused `xmlns` bindings
5887  and adds them to appropriate places by applying c14n normalization rules.
5888  Should not be used together with SOAP 1.1/1.2 encoding style messaging.
5889 
5890 - `SOAP_XML_TREE`: write tree XML without id-ref, while pruning data structure
5891  cycles to prevent nontermination of the serializer for cyclic structures.
5892 
5893 - `SOAP_XML_GRAPH`: write graph (digraph and cyclic graphs with shared pointers
5894  to objects) using id-ref attributes. That is, XML with SOAP multi-ref
5895  encoded id-ref elements. This is a structure-preserving serialization format,
5896  because co-referenced data and also cyclic relations are accurately represented.
5897 
5898 - `SOAP_XML_DEFAULTNS`: uses xmlns default namespace declarations, assuming
5899  that the schema attribute form is "qualified" by default (be warned if it is
5900  not, since attributes in the null namespace will get bound to namespaces!).
5901 
5902 - `SOAP_XML_NIL`: emit empty element with <i>`xsi:nil`</i> for all NULL pointers
5903  serialized.
5904 
5905 - `SOAP_XML_IGNORENS`: the XML parser ignores XML namespaces, i.e. element and
5906  attribute tag names match independent of their namespace.
5907 
5908 - `SOAP_XML_NOTYPE`: removes all <i>`xsi:type`</i> attribuation. This option is usually
5909  not needed unless the receiver rejects all <i>`xsi:type`</i> attributes. This option
5910  may affect the quality of the deserializer, which relies on <i>`xsi:type`</i>
5911  attributes to distinguish base class instances from derived class instances
5912  transported in the XML payloads.
5913 
5914 - `SOAP_IO_CHUNK`: to enable HTTP chunked transfers.
5915 
5916 - `SOAP_IO_STORE`: full buffering of outbound messages.
5917 
5918 - `SOAP_ENC_ZLIB`: compress messages, requires compiling with option <b>`-DWITH_GZIP`</b> and
5919  linking with zlib using option <b>`-lz`</b>.
5920 
5921 - `SOAP_ENC_MIME`: enable MIME attachments, see
5922  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
5923 
5924 - `SOAP_ENC_MTOM`: enable MTOM attachments, see
5925  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
5926 
5927 @note C++ Web service proxy and service classes have their own `soap` context, either
5928 as a base class (with <b>`soapcpp2 -i`</b> option <b>`-i`</b>) or as a pointer member `soap` that points to
5929 a context (with <b>`soapcpp2 -j`</b> option <b>`-j`</b>). These contexts are allocated when the proxy or
5930 service is instantiated with context flags that are passed to the constructor.
5931 
5932 🔝 [Back to table of contents](#)
5933 
5934 Context parameter settings {#params}
5935 ==========================
5936 
5937 After allocation and initializtion of a `soap` context, several context
5938 parameters can be set (some parameters may require 2.8.31 or greater):
5939 
5940 - `unsigned int soap::maxlevel` is the maximum XML nesting depth levels that
5941  the parser permits. Default initialized to `SOAP_MAXLEVEL` (10000), which is
5942  a redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlevel` to a
5943  lower value to restrict XML parsing nesting depth.
5944 
5945 - `long soap::maxlength` is the maximum string content length if not already
5946  constrained by an XML schema validation `maxLength` constraint. Zero means
5947  unlimited string lengths are permitted (unless restricted by XML schema
5948  `maxLength`). Default initialized to `SOAP_MAXLENGTH` (0), which is a
5949  redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlength` to a
5950  positive value to restrict the number of (wide) characters in strings parsed,
5951  restrict hexBinary byte length, and restrict base64Binary byte length.
5952 
5953 - `size_t soap::maxoccurs` is the maximum number of array or container elements
5954  permitted by the parser. Must be greater than zero (0). Default initialized
5955  to `SOAP_MAXOCCURS` (100000), which is a redefinable macro in
5956  <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxoccurs` to a positive value to
5957  restrict the number of array and container elements that can be parsed.
5958 
5959 - `soap::version` is the SOAP version used, with 0 for non-SOAP, 1 for SOAP1.1,
5960  and 2 for SOAP1.2. This value is normally set by web service operations, and
5961  is otherwise 0 (non-SOAP). Use `soap_set_version(struct soap*, short)` to
5962  set the value. This controls XML namespaces and SOAP id-ref serialization
5963  when applicable with an encodingStyle (see below).
5964 
5965 - `const char *soap::encodingStyle` is a string that is used with SOAP
5966  encoding, normally NULL for non-SOAP XML. Set this string to "" (empty
5967  string) to enable SOAP encoding style, which supports id-ref graph
5968  serialization (see also the `SOAP_XML_GRAPH` [context flag](#flags)).
5969 
5970 - `int soap::recvfd` is the file descriptor to read and parse source data from.
5971  Default initialized to 0 (stdin). See also [input and output](#io).
5972 
5973 - `int soap::sendfd` is the file descriptor to write data to. Default
5974  initialized to 1 (stdout). See also [input and output](#io).
5975 
5976 - `const char *is` for C: string to read and parse source data from, overriding
5977  the `recvfd` source. Normally NULL. This value must be reset to NULL or
5978  the parser will continue to read from this string content until the NUL
5979  character. See also [input and output](#io).
5980 
5981 - `std::istream *is` for C++: an input stream to read and parse source data
5982  from, overriding the `recvfd` source. Normally NULL. This value must be
5983  reset to NULL or the parser will continue to read from this stream until EOF.
5984  See also [input and output](#io).
5985 
5986 - `const char **os` for C: points to a string (a `const char *`) that will be
5987  set to point to the string output. Normally NULL. This value must be reset
5988  to NULL or the next output will result in reassigning the pointer to point to
5989  the next string that is output. The strings are automatically deallocated by
5990  `soap_end(soap)`. See also [input and output](#io).
5991 
5992 - `std::ostream *os` for C++: an output stream to write output to. Normally
5993  NULL. This value must be reste to NULL or the next output will be send to
5994  this stream. See also [input and output](#io).
5995 
5996 🔝 [Back to table of contents](#)
5997 
5998 Error handling and reporting {#errors}
5999 ============================
6000 
6001 The gSOAP API functions return `SOAP_OK` (zero) or a non-zero error code. The
6002 error code is stored in `int soap::error` of the current `soap` context.
6003 Error messages can be displayed with:
6004 
6005 - `void soap_stream_fault(struct soap*, std::ostream &os)` for C++ only, prints
6006  the error message to an output stream.
6007 
6008 - `void soap_print_fault(struct soap*, FILE *fd)` prints the error message to a
6009  FILE descriptor.
6010 
6011 - `void soap_sprint_fault(struct soap*, char *buf, size_t len)` saves the error
6012  message to a fixed-size buffer allocated with a maximum length.
6013 
6014 - `void soap_print_fault_location(struct soap*, FILE *fd)` prints the location
6015  and part of the XML where the parser encountered an error.
6016 
6017 C++ exceptions are never raised by the engine or serializers, even when data is
6018 allocated.
6019 
6020 A `SOAP_EOM` error code is returned when memory was exhausted during
6021 processing of input and/or output of data.
6022 
6023 An EOF (`SOAP_EOF` or -1) error code is returned when the parser has hit EOF
6024 but expected more input, or when socket communications timed out. In addition
6025 to the `SOAP_EOF` error, the `int soap::errnum` of the `soap` context is
6026 set to the `errno` value of the operation that failed. For timeouts, the
6027 `soap::ernum` value is always 0 instead of an `errno` error code.
6028 
6029 Use `soap_xml_error_check(soap->error)` to check for XML errors. This returns
6030 true (non-zero) when a parsing and validation error has occurred.
6031 
6032 For example:
6033 
6034 ~~~{.cpp}
6035  #include <sstream>
6036 
6037  struct soap *soap = soap_new1(SOAP_XML_INDENT | SOAP_XML_STRICT | SOAP_XML_TREE);
6038  struct ns__record person;
6039  std::stringstream ss;
6040  ss.str("..."); // XML to parse
6041  soap->is = &ss;
6042  if (soap_read__ns__record(soap, &person))
6043  {
6044  if (soap_xml_error_check(soap->error))
6045  std::cerr << "XML parsing error!" << std::endl;
6046  else
6047  soap_stream_fault(soap, std::cerr);
6048  }
6049  else
6050  {
6051  ... // all OK, use person record
6052  }
6053  soap_destroy(soap); // delete objects
6054  soap_end(soap); // delete other data and temp data
6055  soap_free(soap); // free context
6056 ~~~
6057 
6058 When deploying your application on UNIX and Linux systems, UNIX signal handlers
6059 should be added to your code handle signals, in particular `SIGPIPE`:
6060 
6061 ~~~{.cpp}
6062  signal(SIGPIPE, sigpipe_handler);
6063 ~~~
6064 
6065 where the `sigpipe_handler` is a function:
6066 
6067 ~~~{.cpp}
6068  void sigpipe_handler(int x) { }
6069 ~~~
6070 
6071 Other UNIX signals may have to be handled as well.
6072 
6073 The engine is designed for easy memory cleanup after being interrupted. Use
6074 `soap_destroy(soap)` and `soap_end(soap)`, after which the `soap` context can
6075 be reused.
6076 
6077 🔝 [Back to table of contents](#)
6078 
6079 Features and limitations {#features}
6080 ========================
6081 
6082 In general, to use the generated code:
6083 
6084 - Make sure to `#include "soapH.h"` in your code and also define a namespace
6085  table or `#include "ns.nsmap"` with the generated table, where `ns` is the
6086  namespace prefix for services.
6087 
6088 - Use <b>`soapcpp2 -j`</b> option <b>`-j`</b> (C++ only) to generate C++ proxy and service objects.
6089  The auto-generated files include documented inferfaces. Compile with
6090  <i>`soapC.cpp`</i> and link with <b>`-lgsoap++`</b>, or alternatively compile
6091  <i>`gsoap/stdsoap2.cpp`</i>.
6092 
6093 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: client-side uses the auto-generated
6094  <i>`soapClient.cpp`</i> and <i>`soapC.cpp`</i> (or C versions of those).
6095  Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for C), or
6096  alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`gsoap/stdsoap2.c`</i>
6097  for C).
6098 
6099 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: server-side uses the
6100  auto-generated <i>`soapServer.cpp`</i> and <i>`soapC.cpp`</i> (or C versions
6101  of those). Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for
6102  C), or alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`stdsoap2.c`</i>
6103  for C).
6104 
6105 - Use `soap_new()` or `soap_new1(int flags)` to allocate and initialize a
6106  heap-allocated `soap` context with or without flags. Delete this `soap` context with
6107  `soap_free(struct soap*)`, but only after `soap_destroy(struct soap*)` and
6108  `soap_end(struct soap*)`.
6109 
6110 - Use `soap_init(struct *soap)` or `soap_init1(struct soap*, int flags)` to
6111  initialize a stack-allocated `soap` context with or without flags. End the use of
6112  this context with `soap_done(struct soap*)`, but only after
6113  `soap_destroy(struct soap*)` and `soap_end(struct soap*)`.
6114 
6115 Additional notes with respect to the wsdl2h and soapcpp2 tools:
6116 
6117 - Nested classes, structs, and unions in a interface header file are unnested
6118  by soapcpp2.
6119 
6120 - Use `#import "file.h"` instead of `#include` to import other header files in
6121  a interface header file for soapcpp2. The `#include`, `#define`, and
6122  `#pragma` are accepted by soapcpp2, but are moved to the very start of the
6123  generated code for the C/C++ compiler to include before all generated
6124  definitions. Often it is useful to add an `#include` with a
6125  [volatile type](#toxsd9-2) that includes the actual type declaration, and to
6126  ensure transient types are declared when these are used in a data binding
6127  interface declared in a interface header file for soapcpp2.
6128 
6129 - To remove any SOAP-specific bindings, use <b>`soapcpp2 -0`</b> option <b>`-0`</b>.
6130 
6131 - A interface header file for soapcpp2 should not include any code statements,
6132  only data type declarations. This includes constructor initialization lists
6133  that are not permitted. Use member initializations instead.
6134 
6135 - C++ namespaces are supported. Use <b>`wsdl2h -qname`</b> option
6136  <b>`-qname`</b> to add C++ namespace `name`. Or add a `namespace name { ... }`
6137  to the header file, but the `{ ... }` must cover the entire
6138  header file content from begin to end.
6139 
6140 - Optional XML DOM support can be used to store mixed content or literal XML
6141  content. Otherwise, mixed content may be lost. Use <b>`wsdl2h -d`</b>
6142  option <b>`-d`</b> for XML DOM support and compile and link with
6143  <i>`gsoap/dom.c`</i> or <i>`gsoap/dom.cpp`</i>. For details,
6144  see [XML DOM and XPath](http://www.genivia.com/doc/dom/html).
6145 
6146 🔝 [Back to table of contents](#)
6147 
6148 Removing SOAP namespaces from XML payloads {#nsmap}
6149 ==========================================
6150 
6151 The soapcpp2 tool generates a <i>`.nsmap`</i> file that includes two bindings for SOAP
6152 namespaces. We can remove all SOAP namespaces (and SOAP processing logic) with
6153 <b>`soapcpp2 -0`</b> option <b>`-0`</b> or by simply setting the two entries to NULL:
6154 
6155 ~~~{.cpp}
6156  struct Namespace namespaces[] =
6157  {
6158  {"SOAP-ENV", NULL, NULL, NULL},
6159  {"SOAP-ENC", NULL, NULL, NULL},
6160  ...
6161  };
6162 ~~~
6163 
6164 Once the <i>`.nsmap`</i> is generated, you can copy-paste the content into your
6165 project code. However, if we rerun wsdl2h on updated WSDL/XSD files or
6166 <i>`typemap.dat`</i> declarations then we need to use the updated table.
6167 
6168 In cases that no XML namespaces are used at all, for example with
6169 [XML-RPC](http://www.genivia.com/doc/xml-rpc-json/html), you may use an empty
6170 namespace table:
6171 
6172 ~~~{.cpp}
6173  struct Namespace namespaces[] = {{NULL,NULL,NULL,NULL}};
6174 ~~~
6175 
6176 However, beware that any built-in xsi attributes that are rendered will lack
6177 the proper namespace binding. At least we suggest to use `SOAP_XML_NOTYPE` for
6178 this reason.
6179 
6180 🔝 [Back to table of contents](#)
6181 
6182 Examples {#examples}
6183 ========
6184 
6185 Select the project files below to peruse the source code examples.
6186 
6187 🔝 [Back to table of contents](#)
6188 
6189 Source files
6190 ------------
6191 
6192 - <i>`address.xsd`</i> Address book schema
6193 - <i>`address.cpp`</i> Address book app (reads/writes address.xml file)
6194 - <i>`addresstypemap.dat`</i> Schema namespace prefix name preference for wsdl2h
6195 - <i>`graph.h`</i> Graph data binding (tree, digraph, cyclic graph)
6196 - <i>`graph.cpp`</i> Test graph serialization as tree, digraph, and cyclic
6197 
6198 🔝 [Back to table of contents](#)
6199 
6200 Generated files
6201 ---------------
6202 
6203 - <i>`address.h`</i> data binding interface generated from address.xsd
6204 - <i>`addressStub.h`</i> C++ data binding definitions
6205 - <i>`addressH.h`</i> Serializers
6206 - <i>`addressC.cpp`</i> Serializers
6207 - <i>`address.xml`</i> Address book data generated by address app
6208 - <i>`graphStub.h`</i> C++ data binding definitions
6209 - <i>`graphH.h`</i> Serializers
6210 - <i>`graphC.cpp`</i> Serializers
6211 - <i>`g.xsd`</i> XSD schema with <i>`g:Graph`</i> complexType
6212 - <i>`g.nsmap`</i> xmlns bindings namespace mapping table
6213 
6214 🔝 [Back to table of contents](#)
6215 
6216 Build steps
6217 -----------
6218 
6219 Building the AddressBook example:
6220 
6221  wsdl2h -g -taddresstypemap.dat address.xsd
6222  soapcpp2 -0 -C -S -paddress -I../../import address.h
6223  c++ -I../.. address.cpp addressC.cpp -o address -lgsoap++
6224 
6225 Using <b>`wsdl2h -g -taddresstypemap.dat`</b> option <b>`-g`</b> produces
6226 bindings for global (root) elements in addition to types and option
6227 <b>`-taddresstypemap.dat`</b> specifies a mapping file, see further below.
6228 
6229 In this case the root element <i>`a:address-book`</i> is bound to `_a__address_book`.
6230 The complexType <i>`a:address`</i> is bound to class `a__address`, which is also the
6231 type of `_a__address_book`. This option is not required, but allows you to use
6232 global element tag names when referring to their serializers, instead of their
6233 type name. Using <b>`soapcpp2 -0 -C -S -paddress`</b> option <b>`-0`</b> removes the
6234 SOAP protocol and the combination of the two options <b>`-C`</b> and
6235 <b>`-S`</b> removes client and server code generation (using option <b>`-C`</b>
6236 alone generates client code and using option <b>`-S`</b> alone generates server
6237 code). Option <b>`-paddress`</b> renames the output <i>`soap`</i>-prefixed files to
6238 <i>`address`</i>-prefixed files.
6239 
6240 See the <i>`address.cpp`</i> implementation and [related pages](pages.html).
6241 
6242 The <i>`addresstypemap.dat`</i> file specifies the XML namespace prefix for the
6243 bindings:
6244 
6245  # Bind the address book schema namespace to prefix 'a'
6246 
6247  a = "urn:address-book-example"
6248 
6249  # By default the xsd:dateTime schema type is translated to time_t
6250  # To map xsd:dateTime to struct tm, enable the following line:
6251 
6252  # xsd__dateTime = #import "../../custom/struct_tm.h"
6253 
6254  # ... and compile/link with custom/struct_tm.c
6255 
6256 The DOB field is a <i>`xsd:dateTime`</i>, which is bound to `time_t` by default. To
6257 change this to `struct tm`, enable the import of the `xsd__dateTime` custom
6258 serializer by uncommenting the definition of `xsd__dateTime` in
6259 <i>`addresstypemap.dat`</i>. Then change `soap_dateTime2s` to `soap_xsd__dateTime2s`
6260 in the code.
6261 
6262 Building the graph serialization example:
6263 
6264  soapcpp2 -C -S -pgraph -I../../import graph.h
6265  c++ -I../.. graph.cpp graphC.cpp -o graph -lgsoap++
6266 
6267 To compile without using the <b>`-lgsoap++`</b> library: simply compile
6268 <i>`stdsoap2.cpp`</i> together with the above.
6269 
6270 🔝 [Back to table of contents](#)
6271 
6272 Usage
6273 -----
6274 
6275 To execute the AddressBook example:
6276 
6277  ./address
6278 
6279 To execute the Graph serialization example:
6280 
6281  ./graph
6282