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blob: df5a0199f2b9b5ead11b997278572627c53f8cd1 [file] [log] [blame]
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2 "http://www.w3.org/TR/REC-html40/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]5 <title>The XML library for Gnome</title>
6 <meta name="GENERATOR" content="amaya V2.1">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]7</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]9<body bgcolor="#ffffff">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]10<h1 align="center">The XML library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]11
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]12<h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2>
13
14<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]15<ul>
16 <li><a href="#Introducti">Introduction</a></li>
17 <li><a href="#Documentat">Documentation</a></li>
18 <li><a href="#News">News</a></li>
19 <li><a href="#XML">XML</a></li>
20 <li><a href="#tree">The tree output</a></li>
21 <li><a href="#interface">The SAX interface</a></li>
22 <li><a href="#library">The XML library interfaces</a>
23 <ul>
24 <li><a href="#Invoking">Invoking the parser</a></li>
25 <li><a href="#Building">Building a tree from scratch</a></li>
26 <li><a href="#Traversing">Traversing the tree</a></li>
27 <li><a href="#Modifying">Modifying the tree</a></li>
28 <li><a href="#Saving">Saving the tree</a></li>
29 <li><a href="#Compressio">Compression</a></li>
30 </ul>
31 </li>
32 <li><a href="#Entities">Entities or no entities</a></li>
33 <li><a href="#Namespaces">Namespaces</a></li>
34 <li><a href="#Validation">Validation</a></li>
35 <li><a href="#Principles">DOM principles</a></li>
36 <li><a href="#real">A real example</a></li>
37</ul>
38
39<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]40
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]41<p>This document describes the <a href="http://www.w3.org/XML/">XML</a>
42library provideed in the <a href="http://www.gnome.org/">Gnome</a> framework.
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]43XML is a standard to build tag based structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]44
45<p>The internal document repesentation is as close as possible to the <a
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]46href="http://www.w3.org/DOM/">DOM</a> interfaces.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]47
48<p>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
49interface</a>, <a href="mailto:james@daa.com.au">James Henstridge</a> made <a
50href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">a nice
51documentation</a> expaining how to use it. The interface is as compatible as
52possible with <a href="http://www.jclark.com/xml/expat.html">Expat</a>
53one.</p>
54
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]55<p>There is also a mailing-list <a
Daniel Veillard6bd26dc1999-09-03 14:28:40 +0000[diff] [blame]56href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> for libxml, with an <a
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]57href="http://rpmfind.net/veillard/XML/messages">on-line archive</a>. To
58subscribe to this majordomo based list, send a mail to <a
Daniel Veillard6bd26dc1999-09-03 14:28:40 +0000[diff] [blame]59href="mailto:majordomo@rufus.w3.org">majordomo@rufus.w3.org</a> with
60"subscribe xml" in the <strong>content</strong> of the message.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]61
62<p>This library is released both under the W3C Copyright and the GNU LGP,
63basically everybody should be happy, if not, drop me a mail.</p>
64
65<p>People are invited to use the <a
66href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module to</a> get a
67full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
68Levien</a>, check his <a
69href="http://www.levien.com/gnome/domination.html">DOMination paper</a>. He
70uses it for his implementation of <a
71href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
72href="http://www.levien.com/svg/">gill</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]73
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]74<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]75
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]76<p>The code is commented in a <a href=""></a>way which allow <a
77href="http://rpmfind.net/veillard/XML/libxml.html">extensive documentation</a>
78to be automatically extracted.</p>
79
80<p>At some point I will change the back-end to produce XML documentation in
81addition to SGML Docbook and HTML.</p>
82
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]83<h2><a name="News">News</a></h2>
84
85<p>Latest version is 1.7.1, you can find it on <a
86href="ftp://rpmfind.net/pub/veillard/">rpmfind.net</a> or on the <a
87href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
88as a <a href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml/">source
89archive</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/contrib/rpms/">RPMs
90packages</a>.</p>
91
92<h3>CVS only</h3>
93<ul>
94 <li>snprintf was used unconditionnally, leading to link problems on system
95 were it's not available, fixed </li>
96</ul>
97
98<h3>1.7.1: Sep 24 1999</h3>
99<ul>
100 <li>The basic type for strings manipulated by libxml has been renamed in
101 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
102 is that CHAR was conflicting with a predefined type on Windows. However on
103 non WIN32 environment, compatibility is provided by the way of a
104 <strong>#define </strong>.</li>
105 <li>Changed another error : the use of a structure field called errno, and
106 leading to troubles on platforms where it's a macro</li>
107</ul>
108
109<h3>1.7.0: sep 23 1999</h3>
110<ul>
111 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
112 href="gnome-xml-nanohttp.html">nanohttp</a> module.</li>
113 <li>Added an errno to report errors by another mean than a simple printf
114 like callback</li>
115 <li>Finished ID/IDREF support and checking when validation</li>
116 <li>Serious memory leaks fixed (there is now a <a
117 href="gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
118 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
119 implementation</li>
120 <li>Added an HTML parser front-end</li>
121</ul>
122
123<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]124
125<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for markup
126based structured documents, here is <a name="example">an example</a>:</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]127<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]128&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]129 &lt;head>
130 &lt;title>Welcome to Gnome&lt;/title>
131 &lt;/head>
132 &lt;chapter>
133 &lt;title>The Linux adventure&lt;/title>
134 &lt;p>bla bla bla ...&lt;/p>
135 &lt;image href="linus.gif"/>
136 &lt;p>...&lt;/p>
137 &lt;/chapter>
138&lt;/EXAMPLE></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]139
140<p>The first line specify that it's an XML document and gives useful
141informations about it's encoding. Then the document is a text format whose
142structure is specified by tags between brackets. <strong>Each tag opened have
143to be closed</strong> XML is pedantic about this, not that for example the
144image tag has no content (just an attribute) and is closed by ending up the
145tag with <code>/></code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]146
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]147<p>XML can be applied sucessfully to a wide range or usage from long term
148structured document maintenance where it follows the steps of SGML to simple
149data encoding mechanism like configuration file format (glade), spreadsheets
150(gnumeric), or even shorter lived document like in WebDAV where it is used to
151encode remote call between a client and a server.</p>
152
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]153<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]154
155<p>The parser returns a tree built during the document analysis. The value
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]156returned is an <strong>xmlDocPtr</strong> (i.e. a pointer to an
157<strong>xmlDoc</strong> structure). This structure contains informations like
158the file name, the document type, and a <strong>root</strong> pointer which
159is the root of the document (or more exactly the first child under the root
160which is the document). The tree is made of <strong>xmlNode</strong>s, chained
161in double linked lists of siblings and with childs&lt;->parent relationship.
162An xmlNode can also carry properties (a chain of xmlAttr structures). An
163attribute may have a value which is a list of TEXT or ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]164
165<p>Here is an example (erroneous w.r.t. the XML spec since there should be
166only one ELEMENT under the root):</p>
167
168<p><img src="structure.gif" alt=" structure.gif "></p>
169
170<p>In the source package there is a small program (not installed by default)
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]171called <strong>tester</strong> which parses XML files given as argument and
172prints them back as parsed, this is useful to detect errors both in XML code
173and in the XML parser itself. It has an option <strong>--debug</strong> which
174prints the actual in-memory structure of the document, here is the result with
175the <a href="#example">example</a> given before:</p>
176<pre>DOCUMENT
177version=1.0
178standalone=true
179 ELEMENT EXAMPLE
180 ATTRIBUTE prop1
181 TEXT
182 content=gnome is great
183 ATTRIBUTE prop2
184 ENTITY_REF
185 TEXT
186 content= too
187 ELEMENT head
188 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]189 TEXT
190 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]191 ELEMENT chapter
192 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]193 TEXT
194 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]195 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]196 TEXT
197 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]198 ELEMENT image
199 ATTRIBUTE href
200 TEXT
201 content=linus.gif
202 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]203 TEXT
204 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]205
206<p>This should be useful to learn the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]207
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]208<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]209
210<p>Sometimes the DOM tree output is just to large to fit reasonably into
211memory. In that case and if you don't expect to save back the XML document
212loaded using libxml, it's better to use the SAX interface of libxml. SAX is a
213<strong>callback based interface</strong> to the parser. Before parsing, the
214application layer register a customized set of callbacks which will be called
215by the library as it progresses through the XML input.</p>
216
217<p>To get a more detailed step-by-step guidance on using the SAX interface of
218libxml, <a href="mailto:james@daa.com.au">James Henstridge</a> made <a
219href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">a nice
220documentation.</a></p>
221
222<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
223program located in the gnome-xml module (it's usually not shipped in the
224binary packages of libxml, but you can also find it in the tar source
225distribution). Here is the sequence of callback that would be generated when
226parsing the example given before as reported by testSAX:</p>
227<pre>SAX.setDocumentLocator()
228SAX.startDocument()
229SAX.getEntity(amp)
230SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
231SAX.characters( , 3)
232SAX.startElement(head)
233SAX.characters( , 4)
234SAX.startElement(title)
235SAX.characters(Welcome to Gnome, 16)
236SAX.endElement(title)
237SAX.characters( , 3)
238SAX.endElement(head)
239SAX.characters( , 3)
240SAX.startElement(chapter)
241SAX.characters( , 4)
242SAX.startElement(title)
243SAX.characters(The Linux adventure, 19)
244SAX.endElement(title)
245SAX.characters( , 4)
246SAX.startElement(p)
247SAX.characters(bla bla bla ..., 15)
248SAX.endElement(p)
249SAX.characters( , 4)
250SAX.startElement(image, href='linus.gif')
251SAX.endElement(image)
252SAX.characters( , 4)
253SAX.startElement(p)
254SAX.characters(..., 3)
255SAX.endElement(p)
256SAX.characters( , 3)
257SAX.endElement(chapter)
258SAX.characters( , 1)
259SAX.endElement(EXAMPLE)
260SAX.endDocument()</pre>
261
262<p>Most of the other functionnalities of libxml are based on the DOM tree
263building facility, so nearly everything up to the end of this document
264presuppose the use of the standard DOM tree build. Note that the DOM tree
265itself is built by a set of registered default callbacks, without internal
266specific interface.</p>
267
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]268<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]269
270<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]271using the XML library from the C language. It doesn't intent to be extensive,
272I hope the automatically generated docs will provide the completeness
273required, but as a separated set of documents. The interfaces of the XML
274library are by principle low level, there is nearly zero abstration. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]275interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]276
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]277<h3><a name="Invoking">Invoking the parser</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]278
279<p>Usually, the first thing to do is to read an XML input, the parser accepts
280to parse both memory mapped documents or direct files. The functions are
281defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]282<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]283 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
284 <dd><p>parse a zero terminated string containing the document</p>
285 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]286</dl>
287<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]288 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
289 <dd><p>parse an XML document contained in a file (possibly compressed)</p>
290 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]291</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]292
293<p>This returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]294failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]295
296<p>A couple of comments can be made, first this mean that the parser is
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]297memory-hungry, first to load the document in memory, second to build the tree.
298Reading a document without building the tree will be possible in the future by
299pluggin the code to the SAX interface (see SAX.c).</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]300
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]301<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]302
303<p>The other way to get an XML tree in memory is by building it. Basically
304there is a set of functions dedicated to building new elements, those are also
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]305described in "tree.h", here is for example the piece of code producing the
306example used before:</p>
307<pre> xmlDocPtr doc;
308 xmlNodePtr tree, subtree;
309
310 doc = xmlNewDoc("1.0");
311 doc->root = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
312 xmlSetProp(doc->root, "prop1", "gnome is great");
313 xmlSetProp(doc->root, "prop2", "&amp;linux; too");
314 tree = xmlNewChild(doc->root, NULL, "head", NULL);
315 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
316 tree = xmlNewChild(doc->root, NULL, "chapter", NULL);
317 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
318 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
319 subtree = xmlNewChild(tree, NULL, "image", NULL);
320 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]321
322<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]323
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]324<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]325
326<p>Basically by including "tree.h" your code has access to the internal
327structure of all the element of the tree. The names should be somewhat simple
328like <strong>parent</strong>, <strong>childs</strong>, <strong>next</strong>,
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]329<strong>prev</strong>, <strong>properties</strong>, etc... For example still
330with the previous example:</p>
331<pre><code>doc->root->childs->childs</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]332
333<p>points to the title element,</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]334<pre>doc->root->childs->next->child->child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]335
336<p>points to the text node containing the chapter titlle "The Linux adventure"
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]337and</p>
338<pre>doc->root->properties->next->val</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]339
340<p>points to the entity reference containing the value of "&amp;linux" at the
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]341beginning of the second attribute of the root element "EXAMPLE".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]342
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]343<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]344
345<p>functions are provided to read and write the document content:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]346<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]347 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
348 xmlChar *value);</code></dt>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]349 <dd><p>This set (or change) an attribute carried by an ELEMENT node the
350 value can be NULL</p>
351 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]352</dl>
353<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]354 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]355 *name);</code></dt>
356 <dd><p>This function returns a pointer to the property content, note that
357 no extra copy is made</p>
358 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]359</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]360
361<p>Two functions must be used to read an write the text associated to
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]362elements:</p>
363<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]364 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]365 *value);</code></dt>
366 <dd><p>This function takes an "external" string and convert it to one text
367 node or possibly to a list of entity and text nodes. All non-predefined
368 entity references like &amp;Gnome; will be stored internally as an
369 entity node, hence the result of the function may not be a single
370 node.</p>
371 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]372</dl>
373<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]374 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]375 inLine);</code></dt>
376 <dd><p>this is the dual function, which generate a new string containing
377 the content of the text and entity nodes. Note the extra argument
378 inLine, if set to 1 instead of returning the &amp;Gnome; XML encoding in
379 the string it will substitute it with it's value say "GNU Network Object
380 Model Environment". Set it if you want to use the string for non XML
381 usage like User Interface.</p>
382 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]383</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]384
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]385<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]386
387<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]388<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]389 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]390 *size);</code></dt>
391 <dd><p>returns a buffer where the document has been saved</p>
392 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]393</dl>
394<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]395 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
396 <dd><p>dumps a buffer to an open file descriptor</p>
397 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]398</dl>
399<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]400 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
401 <dd><p>save the document ot a file. In that case the compression interface
402 is triggered if turned on</p>
403 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]404</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]405
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]406<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]407
408<p>The library handle transparently compression when doing file based
409accesses, the level of compression on saves can be tuned either globally or
410individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]411<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]412 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
413 <dd><p>Get the document compression ratio (0-9)</p>
414 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]415</dl>
416<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]417 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
418 <dd><p>Set the document compression ratio</p>
419 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]420</dl>
421<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]422 <dt><code>int xmlGetCompressMode(void);</code></dt>
423 <dd><p>Get the default compression ratio</p>
424 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]425</dl>
426<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]427 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
428 <dd><p>set the default compression ratio</p>
429 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]430</dl>
431
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]432<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]433
434<p>Entities principle is similar to simple C macros. They define an
435abbreviation for a given string that you can reuse many time through the
436content of your document. They are especially useful when frequent occurrences
437of a given string may occur within a document or to confine the change needed
438to a document to a restricted area in the internal subset of the document (at
439the beginning). Example:</p>
440<pre>1 &lt;?xml version="1.0"?>
4412 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
4423 &lt;!ENTITY xml "Extensible Markup Language">
4434 ]>
4445 &lt;EXAMPLE>
4456 &amp;xml;
4467 &lt;/EXAMPLE>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]447</pre>
448
449<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]450it's name with '&amp;' and following it by ';' without any spaces added. There
451are 5 predefined entities in libxml allowing to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]452predefined meaning in some parts of the xml document content:
453<strong>&amp;lt;</strong> for the letter '&lt;', <strong>&amp;gt;</strong> for
454the letter '>', <strong>&amp;apos;</strong> for the letter ''',
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]455<strong>&amp;quot;</strong> for the letter '"', and <strong>&amp;amp;</strong>
456for the letter '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]457
458<p>One of the problems related to entities is that you may want the parser to
459substitute entities content to see the replacement text in your application,
460or you may prefer keeping entities references as such in the content to be
461able to save the document back without loosing this usually precious
462information (if the user went through the pain of explicitley defining
463entities, he may have a a rather negative attitude if you blindly susbtitute
464them as saving time). The function <a
465href="gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
466allows to check and change the behaviour, which is to not substitute entities
467by default.</p>
468
469<p>Here is the DOM tree built by libxml for the previous document in the
470default case:</p>
471<pre>/gnome/src/gnome-xml -> ./tester --debug test/ent1
472DOCUMENT
473version=1.0
474 ELEMENT EXAMPLE
475 TEXT
476 content=
477 ENTITY_REF
478 INTERNAL_GENERAL_ENTITY xml
479 content=Extensible Markup Language
480 TEXT
481 content=</pre>
482
483<p>And here is the result when substituting entities:</p>
484<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
485DOCUMENT
486version=1.0
487 ELEMENT EXAMPLE
488 TEXT
489 content= Extensible Markup Language</pre>
490
491<p>So entities or no entities ? Basically it depends on your use case, I
492suggest to keep the non-substituting default behaviour and avoid using
493entities in your XML document or data if you are not willing to handle the
494entity references elements in the DOM tree.</p>
495
496<p>Note that at save time libxml enforce the conversion of the predefined
497entities where necessary to prevent well-formedness problems, and will also
498transparently replace those with chars (i.e. will not generate entity
499reference elements in the DOM tree nor call the reference() SAX callback when
500finding them in the input).</p>
501
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]502<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]503
504<p>The libxml library implement namespace @@ support by recognizing namespace
505contructs in the input, and does namespace lookup automatically when building
506the DOM tree. A namespace declaration is associated with an in-memory
507structure and all elements or attributes within that namespace point to it.
508Hence testing the namespace is a simple and fast equality operation at the
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]509user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]510
511<p>I suggest it that people using libxml use a namespace, and declare it on
512the root element of their document as the default namespace. Then they dont
513need to happend the prefix in the content but we will have a basis for future
514semantic refinement and merging of data from different sources. This doesn't
515augment significantly the size of the XML output, but significantly increase
516it's value in the long-term.</p>
517
518<p>Concerning the namespace value, this has to be an URL, but this doesn't
519have to point to any existing resource on the Web. I suggest using an URL
520within a domain you control, which makes sense and if possible holding some
521kind of versionning informations. For example
522<code>"http://www.gnome.org/gnumeric/1.0"</code> is a good namespace scheme.
523Then when you load a file, make sure that a namespace carrying the
524version-independant prefix is installed on the root element of your document,
525and if the version information don't match something you know, warn the user
526and be liberal in what you accept as the input. Also do *not* try to base
527namespace checking on the prefix value &lt;foo:text> may be exactly the same
528as &lt;bar:text> in another document, what really matter is the URI
529associated with the element or the attribute, not the prefix string which is
530just a shortcut for the full URI.</p>
531
532<p>@@Interfaces@@</p>
533
534<p>@@Examples@@</p>
535
536<p>Usually people object using namespace in the case of validation, I object
537this and will make sure that using namespaces won't break validity checking,
538so even is you plan or are using validation I strongly suggest to add
539namespaces to your document. A default namespace scheme
540<code>xmlns="http://...."</code> should not break validity even on less
541flexible parsers. Now using namespace to mix and differenciate content coming
542from mutliple Dtd will certainly break current validation schemes, I will try
543to provide ways to do this, but this may not be portable or standardized.</p>
544
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]545<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]546
547<p>Well what is validation and what is a DTD ?</p>
548
549<p>Validation is the process of checking a document against a set of
550construction rules, a <strong>DTD</strong> (Document Type Definition) is such
551a set of rules.</p>
552
553<p>The validation process and building DTDs are the two most difficult parts
554of XML life cycle. Briefly a DTD defines all the possibles element to be
555found within your document, what is the formal shape of your document tree (by
556defining the allowed content of an element, either text, a regular expression
557for the allowed list of children, or mixed content i.e. both text and childs).
558The DTD also defines the allowed attributes for all elements and the types of
559the attributes. For more detailed informations, I suggest to read the related
560parts of the XML specification, the examples found under
561gnome-xml/test/valid/dtd and the large amount of books available on XML. The
562dia example in gnome-xml/test/valid should be both simple and complete enough
563to allow you to build your own.</p>
564
565<p>A word of warning, building a good DTD which will fit your needs of your
566application in the long-term is far from trivial, however the extra level of
567quality it can insure is well worth the price for some sets of applications or
568if you already have already a DTD defined for your application field.</p>
569
570<p>The validation is not completely finished but in a (very IMHO) usable
571state. Until a real validation interface is defined the way to do it is to
572define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
573variable to 1, this will of course be changed at some point:</p>
574
575<p>extern int xmlDoValidityCheckingDefaultValue;</p>
576
577<p>...</p>
578
579<p>xmlDoValidityCheckingDefaultValue = 1;</p>
580
581<p></p>
582
583<p>To handle external entities, use the function
584<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
585link in you HTTP/FTP/Entities database library to the standard libxml
586core.</p>
587
588<p>@@interfaces@@</p>
589
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]590<h2><a name="DOM"><a name="Principles">DOM Principles</a></a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]591
592<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document Object
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]593Model</em> this is an API for accessing XML or HTML structured documents.
594Native support for DOM in Gnome is on the way (module gnome-dom), and it will
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]595be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]596files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]597set of IDL (or Java) interfaces allowing to traverse and manipulate a
598document. The DOM library will allow accessing and modifying "live" documents
599presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]600
601<p><img src="DOM.gif" alt=" DOM.gif "></p>
602
603<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]604embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]605
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]606<p>The current DOM implementation on top of libxml is the <a
607href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
608a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
609Levien</a>.</p>
610
611<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
612
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]613<h2><a name="Example"><a name="real">A real example</a></a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]614
615<p>Here is a real size example, where the actual content of the application
616data is not kept in the DOM tree but uses internal structures. It is based on
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]617a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]618storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
619base</a>:</p>
620<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]621&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
622 &lt;gjob:Jobs>
623
624 &lt;gjob:Job>
625 &lt;gjob:Project ID="3"/>
626 &lt;gjob:Application>GBackup&lt;/gjob:Application>
627 &lt;gjob:Category>Development&lt;/gjob:Category>
628
629 &lt;gjob:Update>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]630 &lt;gjob:Status>Open&lt;/gjob:Status>
631 &lt;gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]632 &lt;gjob:Salary>USD 0.00&lt;/gjob:Salary>
633 &lt;/gjob:Update>
634
635 &lt;gjob:Developers>
636 &lt;gjob:Developer>
637 &lt;/gjob:Developer>
638 &lt;/gjob:Developers>
639
640 &lt;gjob:Contact>
641 &lt;gjob:Person>Nathan Clemons&lt;/gjob:Person>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]642 &lt;gjob:Email>nathan@windsofstorm.net&lt;/gjob:Email>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]643 &lt;gjob:Company>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]644 &lt;/gjob:Company>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]645 &lt;gjob:Organisation>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]646 &lt;/gjob:Organisation>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]647 &lt;gjob:Webpage>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]648 &lt;/gjob:Webpage>
649 &lt;gjob:Snailmail>
650 &lt;/gjob:Snailmail>
651 &lt;gjob:Phone>
652 &lt;/gjob:Phone>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]653 &lt;/gjob:Contact>
654
655 &lt;gjob:Requirements>
656 The program should be released as free software, under the GPL.
657 &lt;/gjob:Requirements>
658
659 &lt;gjob:Skills>
660 &lt;/gjob:Skills>
661
662 &lt;gjob:Details>
663 A GNOME based system that will allow a superuser to configure
664 compressed and uncompressed files and/or file systems to be backed
665 up with a supported media in the system. This should be able to
666 perform via find commands generating a list of files that are passed
667 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
668 or via operations performed on the filesystem itself. Email
669 notification and GUI status display very important.
670 &lt;/gjob:Details>
671
672 &lt;/gjob:Job>
673
674 &lt;/gjob:Jobs>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]675&lt;/gjob:Helping></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]676
677<p>While loading the XML file into an internal DOM tree is a matter of calling
678only a couple of functions, browsing the tree to gather the informations and
679generate the internals structures is harder, and more error prone.</p>
680
681<p>The suggested principle is to be tolerant with respect to the input
682structure. For example the ordering of the attributes is not significant, Cthe
683XML specification is clear about it. It's also usually a good idea to not be
684dependant of the orders of the childs of a given node, unless it really makes
685things harder. Here is some code to parse the informations for a person:</p>
686<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]687 * A person record
688 */
689typedef struct person {
690 char *name;
691 char *email;
692 char *company;
693 char *organisation;
694 char *smail;
695 char *webPage;
696 char *phone;
697} person, *personPtr;
698
699/*
700 * And the code needed to parse it
701 */
702personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
703 personPtr ret = NULL;
704
705DEBUG("parsePerson\n");
706 /*
707 * allocate the struct
708 */
709 ret = (personPtr) malloc(sizeof(person));
710 if (ret == NULL) {
711 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]712 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]713 }
714 memset(ret, 0, sizeof(person));
715
716 /* We don't care what the top level element name is */
717 cur = cur->childs;
718 while (cur != NULL) {
719 if ((!strcmp(cur->name, "Person")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]720 ret->name = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]721 if ((!strcmp(cur->name, "Email")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]722 ret->email = xmlNodeListGetString(doc, cur->childs, 1);
723 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]724 }
725
726 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]727}</pre>
728
729<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]730<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]731 <li>Usually a recursive parsing style is the more convenient one, XML data
732 being by nature subject to repetitive constructs and usualy exibit highly
733 stuctured patterns.</li>
734 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
735 the pointer to the global XML document and the namespace reserved to the
736 application. Document wide information are needed for example to decode
737 entities and it's a good coding practice to define a namespace for your
738 application set of data and test that the element and attributes you're
739 analyzing actually pertains to your application space. This is done by a
740 simple equality test (cur->ns == ns).</li>
741 <li>To retrieve text and attributes value, it is suggested to use the
742 function <em>xmlNodeListGetString</em> to gather all the text and entity
743 reference nodes generated by the DOM output and produce an single text
744 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]745</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]746
747<p>Here is another piece of code used to parse another level of the
748structure:</p>
749<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]750 * a Description for a Job
751 */
752typedef struct job {
753 char *projectID;
754 char *application;
755 char *category;
756 personPtr contact;
757 int nbDevelopers;
758 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
759} job, *jobPtr;
760
761/*
762 * And the code needed to parse it
763 */
764jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
765 jobPtr ret = NULL;
766
767DEBUG("parseJob\n");
768 /*
769 * allocate the struct
770 */
771 ret = (jobPtr) malloc(sizeof(job));
772 if (ret == NULL) {
773 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]774 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]775 }
776 memset(ret, 0, sizeof(job));
777
778 /* We don't care what the top level element name is */
779 cur = cur->childs;
780 while (cur != NULL) {
781
782 if ((!strcmp(cur->name, "Project")) &amp;&amp; (cur->ns == ns)) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]783 ret->projectID = xmlGetProp(cur, "ID");
784 if (ret->projectID == NULL) {
785 fprintf(stderr, "Project has no ID\n");
786 }
787 }
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]788 if ((!strcmp(cur->name, "Application")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]789 ret->application = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]790 if ((!strcmp(cur->name, "Category")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]791 ret->category = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]792 if ((!strcmp(cur->name, "Contact")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]793 ret->contact = parsePerson(doc, ns, cur);
794 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]795 }
796
797 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]798}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]799
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]800<p>One can notice that once used to it, writing this kind of code is quite
801simple, but boring. Ultimately, it could be possble to write stubbers taking
802either C data structure definitions, a set of XML examples or an XML DTD and
803produce the code needed to import and export the content between C data and
804XML storage. This is left as an exercise to the reader :-)</p>
805
806<p>Feel free to use <a href="gjobread.c">the code for the full C parsing
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]807example</a> as a template, it is also available with Makefile in the Gnome CVS
808base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]809
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]810<p></p>
811
812<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
813
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame^]814<p>$Id: xml.html,v 1.9 1999/09/23 22:19:20 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]815</body>
816</html>