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gerrit-public.fairphone.software / platform / external / libxml2 / 9d343c4af567e67c28e8a867f44fab76cefeb5ef / . / doc / xml.html
blob: 5b66779bdc8c83c6c62c57d7930772d62570baf5 [file] [log] [blame]
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1<html>
2<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]3 <title>The XML C library for Gnome</title>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame^]4 <meta name="GENERATOR" content="amaya V4.0">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]6</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]7
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]8<body bgcolor="#ffffff">
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9<p><a href="http://www.gnome.org/"><img src="smallfootonly.gif"
10alt="Gnome Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png"
11alt="W3C Logo"></a></p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]12
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]13<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]14
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]15<h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2>
16
17<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]18<ul>
19 <li><a href="#Introducti">Introduction</a></li>
20 <li><a href="#Documentat">Documentation</a></li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]21 <li><a href="#Reporting">Reporting bugs and getting help</a></li>
22 <li><a href="#help">how to help</a></li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]23 <li><a href="#Downloads">Downloads</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]24 <li><a href="#News">News</a></li>
25 <li><a href="#XML">XML</a></li>
26 <li><a href="#tree">The tree output</a></li>
27 <li><a href="#interface">The SAX interface</a></li>
28 <li><a href="#library">The XML library interfaces</a>
29 <ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]30 <li><a href="#Invoking">Invoking the parser: the pull way</a></li>
31 <li><a href="#Invoking">Invoking the parser: the push way</a></li>
32 <li><a href="#Invoking2">Invoking the parser: the SAX interface</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]33 <li><a href="#Building">Building a tree from scratch</a></li>
34 <li><a href="#Traversing">Traversing the tree</a></li>
35 <li><a href="#Modifying">Modifying the tree</a></li>
36 <li><a href="#Saving">Saving the tree</a></li>
37 <li><a href="#Compressio">Compression</a></li>
38 </ul>
39 </li>
40 <li><a href="#Entities">Entities or no entities</a></li>
41 <li><a href="#Namespaces">Namespaces</a></li>
42 <li><a href="#Validation">Validation</a></li>
43 <li><a href="#Principles">DOM principles</a></li>
44 <li><a href="#real">A real example</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]45 <li><a href="#Contributi">Contributions</a></li>
46</ul>
47
48<p>Separate documents:</p>
49<ul>
50 <li><a href="upgrade.html">upgrade instructions for migrating to
51 libxml2</a></li>
52 <li><a href="encoding.html">libxml Internationalization support</a></li>
53 <li><a href="xmlio.html">libxml Input/Output interfaces</a></li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]54 <li><a href="xmlmem.html">libxml Memory interfaces</a></li>
Daniel Veillard300f7d62000-11-24 13:04:04 +0000[diff] [blame]55 <li><a href="xmldtd.html">a short introduction about DTDs and
56 libxml</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]57</ul>
58
59<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]60
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]61<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]62href="http://www.w3.org/XML/">XML</a> C library developped for the <a
63href="http://www.gnome.org/">Gnome</a> project. <a
64href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
65structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]66
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]67<p>Here are some key points about libxml:</p>
68<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]69 <li>Libxml exports Push and Pull type parser interfaces for both XML and
70 HTML.</li>
71 <li>Libxml can do Dtd validation at parse time, using a parsed document
72 instance, or with an arbitrary Dtd.</li>
73 <li>Libxml now includes a nearly complete <a
74 href="http://www.w3.org/TR/xpath">XPath</a> and <a
Daniel Veillard0c069222000-10-21 09:25:52 +0000[diff] [blame]75 href="http://www.w3.org/TR/xptr">XPointer</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]76 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]77 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]78 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]79 <li>Basic support for HTTP and FTP client allowing to fetch remote
80 resources</li>
81 <li>The design of modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]82 <li>The internal document repesentation is as close as possible to the <a
83 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
84 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]85 like interface</a>; the interface is designed to be compatible with <a
86 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]87 <li>This library is released both under the <a
88 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]89 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
90 LGPL</a>. Use either at your convenience, basically this should make
91 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]92</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]93
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]94<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]95
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]96<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]97<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]98 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]99 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]100 documentation</a> automatically extracted from code comments (using <a
101 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
102 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]103 <li>Look at the documentation about <a href="encoding.html">libxml
104 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]105 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]106 examples</a> on how to use libxml.</li>
107 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
108 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
109 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]110 <li>George Lebl wrote <a
111 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]112 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]113 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
114 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
115 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]116 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]117 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
118 href="http://www.levien.com/svg/">gill</a>. Check his <a
119 href="http://www.levien.com/gnome/domination.html">DOMination
120 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]121 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
122 file</a></li>
123 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
124 starting a new project using libxml you should really use the 2.x
125 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]126 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]127 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]128</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]129
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]130<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]131
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]132<p>Well, bugs or missing features are always possible, and I will make a point
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]133of fixing them in a timely fashion. The best way to report a bug is to use the
134<a href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug tracking
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]135database</a> (make sure to use the "gnome-xml" module name, not libxml or
136libxml2). I look at reports there regularly and it's good to have a reminder
137when a bug is still open. Check the <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]138href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]139and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]140
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]141<p>There is also a mailing-list <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]142href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> for libxml, with an <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]143href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]144majordomo based list, send a mail message to <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]145href="mailto:majordomo@rpmfind.net">majordomo@rpmfind.net</a> with "subscribe
146xml" in the <strong>content</strong> of the message.</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]147
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]148<p>Alternatively, you can just send the bug to the <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]149href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> list, if it's really libxml
150related I will approve it..</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]151
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]152<p>Of course, bugs reports with a suggested patch for fixing them will
153probably be processed faster.</p>
154
155<p>If you're looking for help, a quick look at <a
156href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
157provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]158questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]159documentantion</a> is not as polished as I would like (i need to learn more
160about Docbook), but it's a good starting point.</p>
161
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]162<h2><a name="help">How to help</a></h2>
163
164<p>You can help the project in various ways, the best thing to do first is to
165subscribe to the mailing-list as explained before, check the <a
166href="http://xmlsoft.org/messages/">archives </a>and the <a
167href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug
168database:</a>:</p>
169<ol>
170 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]171 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]172 be integrated in all cases but help pinpointing portability problems
173 and</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]174 <li>provice documentation fixes (either as patches to the code comments or
175 as HTML diffs).</li>
176 <li>provide new documentations pieces (translations, examples, etc ...)</li>
177 <li>Check the TODO file and try to close one of the items</li>
178 <li>take one of the points raised in the archive or the bug database and
179 provide a fix. <a href="mailto:Daniel.Veillard@w3.org">Get in touch with
180 me </a>before to avoid synchronization problems and check that the
181 suggested fix will fit in nicely :-)</li>
182</ol>
183
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]184<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]185
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]186<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]187href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]188href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]189as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]190archive</a> or <a
191href="ftp://ftp.gnome.org/pub/GNOME/contrib/redhat/SRPMS/">RPM packages</a>.
192(NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]193href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
194href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]195packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]196
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]197<p><a name="Snapshot">Snapshot:</a></p>
198<ul>
199 <li>Code from the W3C cvs base libxml <a
200 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
201 <li>Docs, content of the web site, the list archive included <a
202 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
203</ul>
204
205<p><a name="Contribs">Contribs:</a></p>
206
207<p>I do accept external contributions, especially if compiling on another
208platform, get in touch with me to upload the package. I will keep them in the
209<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
210
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]211<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]212<ul>
213 <li><p>The <a href="http://dev.w3.org/cvsweb/XML/">W3C CVS base</a>,
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]214 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]215 this base for my own development, so it's updated more regularly, but the
216 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]217 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]218 password: anonymous
219 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]220 </li>
221 <li><p>The <a
222 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]223 CVS base</a>. Check the <a
224 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
225 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]226 </li>
227</ul>
228
229<h2><a name="News">News</a></h2>
230
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]231<h3>CVS only : check the <a
232href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]233for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]234
235<p>Item floating around but not actively worked on, get in touch with me if
236you want to test those</p>
237<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]238 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
239 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]240 <li>working on HTML and XML links recognition layers</li>
241 <li>parsing/import of Docbook SGML docs</li>
242</ul>
243
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame^]244<p>2.2.9: Nov 25 2000</p>
245<ul>
246 <li>Fix the Windows problems of 2.2.8</li>
247 <li>integrate OpenVMS patches</li>
248 <li>better handling of some nasty HTML input</li>
249 <li>Improved the XPointer implementation</li>
250 <li>integrate a number of provided patches</li>
251</ul>
252
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]253<h3>2.2.8: Nov 13 2000</h3>
254<ul>
255 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
256 support</li>
257 <li>Patch in conditional section handling</li>
258 <li>updated MS compiler project</li>
259 <li>fixed some XPath problems</li>
260 <li>added an URI escaping function</li>
261 <li>some other bug fixes</li>
262</ul>
263
264<h3>2.2.7: Oct 31 2000</h3>
265<ul>
266 <li>added message redirection</li>
267 <li>XPath improvements (thanks TOM !)</li>
268 <li>xmlIOParseDTD() added</li>
269 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
270 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
271</ul>
272
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]273<h3>2.2.6: Oct 25 2000:</h3>
274<ul>
275 <li>Added an hash table module, migrated a number of internal structure to
276 those</li>
277 <li>Fixed a posteriori validation problems</li>
278 <li>HTTP module cleanups</li>
279 <li>HTML parser improvements (tag errors, script/style handling, attribute
280 normalization)</li>
281 <li>coalescing of adjacent text nodes</li>
282 <li>couple of XPath bug fixes, exported the internal API</li>
283</ul>
284
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]285<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]286<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]287 <li>XPointer implementation and testsuite</li>
288 <li>Lot of XPath fixes, added variable and functions registration, more
289 tests</li>
290 <li>Portability fixes, lots of enhancements toward an easy Windows build and
291 release</li>
292 <li>Late validation fixes</li>
293 <li>Integrated a lot of contributed patches</li>
294 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]295 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]296</ul>
297
298<h3>2.2.4: Oct 1 2000:</h3>
299<ul>
300 <li>main XPath problem fixed</li>
301 <li>Integrated portability patches for Windows</li>
302 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]303</ul>
304
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]305<h3>2.2.3: Sep 17 2000</h3>
306<ul>
307 <li>bug fixes</li>
308 <li>cleanup of entity handling code</li>
309 <li>overall review of all loops in the parsers, all sprintf usage has been
310 checked too</li>
311 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
312 works smoothly now.</li>
313</ul>
314
315<h3>1.8.10: Sep 6 2000</h3>
316<ul>
317 <li>bug fix release for some Gnome projects</li>
318</ul>
319
320<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]321<ul>
322 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]323 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]324</ul>
325
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]326<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]327<ul>
328 <li>a purely bug fixes release</li>
329 <li>fixed an encoding support problem when parsing from a memory block</li>
330 <li>fixed a DOCTYPE parsing problem</li>
331 <li>removed a bug in the function allowing to override the memory allocation
332 routines</li>
333</ul>
334
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]335<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]336<ul>
337 <li>applied a lot of portability fixes</li>
338 <li>better encoding support/cleanup and saving (content is now always
339 encoded in UTF-8)</li>
340 <li>the HTML parser now correctly handles encodings</li>
341 <li>added xmlHasProp()</li>
342 <li>fixed a serious problem with &amp;#38;</li>
343 <li>propagated the fix to FTP client</li>
344 <li>cleanup, bugfixes, etc ...</li>
345 <li>Added a page about <a href="encoding.html">libxml Internationalization
346 support</a></li>
347</ul>
348
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]349<h3>1.8.9: July 9 2000</h3>
350<ul>
351 <li>fixed the spec the RPMs should be better</li>
352 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
353 rpmfind users problem</li>
354</ul>
355
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]356<h3>2.1.1: July 1 2000</h3>
357<ul>
358 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
359 <li>improvements on the HTML parser</li>
360</ul>
361
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]362<h3>2.1.0 and 1.8.8: June 29 2000</h3>
363<ul>
364 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
365 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
366 about &amp;#38; charref parsing</li>
367 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
368 also contains numerous fixes and enhancements:
369 <ul>
370 <li>added xmlStopParser() to stop parsing</li>
371 <li>improved a lot parsing speed when there is large CDATA blocs</li>
372 <li>includes XPath patches provided by Picdar Technology</li>
373 <li>tried to fix as much as possible DtD validation and namespace
374 related problems</li>
375 <li>output to a given encoding has been added/tested</li>
376 <li>lot of various fixes</li>
377 </ul>
378 </li>
379</ul>
380
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]381<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]382<ul>
383 <li>First public release of libxml2. If you are using libxml, it's a good
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]384 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
385 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
386 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]387 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]388 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]389 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]390 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]391 <pre>#include "xxx.h"</pre>
392 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]393 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
394 <li>the memory allocation routines used by libxml can now be overloaded
395 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]396 <li>The previously CVS only tool tester has been renamed
397 <strong>xmllint</strong> and is now installed as part of the libxml2
398 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]399 <li>The I/O interface has been revamped. There is now ways to plug in
400 specific I/O modules, either at the URI scheme detection level using
401 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
402 parser context using xmlCreateIOParserCtxt()</li>
403 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
404 number of the libxml module in use</li>
405 <li>a number of optional features of libxml can now be excluded at configure
406 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]407</ul>
408
409<h3>2.0.0beta: Mar 14 2000</h3>
410<ul>
411 <li>This is a first Beta release of libxml version 2</li>
412 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
413 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
414 tar and RPMs</li>
415 <li>This version is now the head in the Gnome CVS base, the old one is
416 available under the tag LIB_XML_1_X</li>
417 <li>This includes a very large set of changes. Froma programmatic point of
418 view applications should not have to be modified too much, check the <a
419 href="upgrade.html">upgrade page</a></li>
420 <li>Some interfaces may changes (especially a bit about encoding).</li>
421 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]422 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]423 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
424 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]425 <li>Better handling of entities, especially well formedness checking and
426 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]427 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]428 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]429 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
430 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]431 </ul>
432 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]433 <li>Serious progress were made toward compliance, <a
434 href="conf/result.html">here are the result of the test</a> against the
435 OASIS testsuite (except the japanese tests since I don't support that
436 encoding yet). This URL is rebuilt every couple of hours using the CVS
437 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]438</ul>
439
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]440<h3>1.8.7: Mar 6 2000</h3>
441<ul>
442 <li>This is a bug fix release:</li>
443 <li>It is possible to disable the ignorable blanks heuristic used by
444 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
445 that for adherence to XML spec, this behaviour will be disabled by default
446 in 2.x . The same function will allow to keep compatibility for old
447 code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]448 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
449 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]450 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
451 compilation on some platforms has been fixed</li>
452 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
453 URIs</li>
454</ul>
455
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]456<h3>1.8.6: Jan 31 2000</h3>
457<ul>
458 <li>added a nanoFTP transport module, debugged until the new version of <a
459 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
460 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]461</ul>
462
463<h3>1.8.5: Jan 21 2000</h3>
464<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]465 <li>adding APIs to parse a well balanced chunk of XML (production <a
466 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
467 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]468 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]469 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
470 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]471 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
472 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]473</ul>
474
475<h3>1.8.4: Jan 13 2000</h3>
476<ul>
477 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
478 <li>all exit() call should have been removed from libxml</li>
479 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
480 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]481</ul>
482
483<h3>1.8.3: Jan 5 2000</h3>
484<ul>
485 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]486 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]487 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]488 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]489 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
490 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]491 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]492 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]493 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]494</ul>
495
496<h3>1.8.2: Dec 21 1999</h3>
497<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]498 <li>I got another problem with includes and C++, I hope this issue is fixed
499 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]500 <li>Added a few tree modification functions: xmlReplaceNode,
501 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
502 xmlDocSetRootElement</li>
503 <li>Tried to improve the HTML output with help from <a
504 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]505</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]506
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]507<h3>1.8.1: Dec 18 1999</h3>
508<ul>
509 <li>various patches to avoid troubles when using libxml with C++ compilers
510 the "namespace" keyword and C escaping in include files</li>
511 <li>a problem in one of the core macros IS_CHAR was corrected</li>
512 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
513 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]514 <li>fixed a posteriori validation (validation after parsing, or by using a
515 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]516 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]517</ul>
518
519<h3>1.8.0: Dec 12 1999</h3>
520<ul>
521 <li>cleanup, especially memory wise</li>
522 <li>the parser should be more reliable, especially the HTML one, it should
523 not crash, whatever the input !</li>
524 <li>Integrated various patches, especially a speedup improvement for large
525 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
526 configure with --with-buffers to enable them.</li>
527 <li>attribute normalization, oops should have been added long ago !</li>
528 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
529 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]530</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]531
532<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]533<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]534 <li>Lots of HTML improvement</li>
535 <li>Fixed some errors when saving both XML and HTML</li>
536 <li>More examples, the regression tests should now look clean</li>
537 <li>Fixed a bug with contiguous charref</li>
538</ul>
539
540<h3>1.7.3: Sep 29 1999</h3>
541<ul>
542 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]543 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]544 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]545</ul>
546
547<h3>1.7.1: Sep 24 1999</h3>
548<ul>
549 <li>The basic type for strings manipulated by libxml has been renamed in
550 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
551 is that CHAR was conflicting with a predefined type on Windows. However on
552 non WIN32 environment, compatibility is provided by the way of a
553 <strong>#define </strong>.</li>
554 <li>Changed another error : the use of a structure field called errno, and
555 leading to troubles on platforms where it's a macro</li>
556</ul>
557
558<h3>1.7.0: sep 23 1999</h3>
559<ul>
560 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]561 href="html/gnome-xml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]562 <li>Added an errno to report errors by another mean than a simple printf
563 like callback</li>
564 <li>Finished ID/IDREF support and checking when validation</li>
565 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]566 href="html/gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]567 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
568 implementation</li>
569 <li>Added an HTML parser front-end</li>
570</ul>
571
572<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]573
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]574<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]575markup-based structured documents. Here is <a name="example">an example XML
576document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]577<pre>&lt;?xml version="1.0"?&gt;
578&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
579 &lt;head&gt;
580 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
581 &lt;/head&gt;
582 &lt;chapter&gt;
583 &lt;title&gt;The Linux adventure&lt;/title&gt;
584 &lt;p&gt;bla bla bla ...&lt;/p&gt;
585 &lt;image href="linus.gif"/&gt;
586 &lt;p&gt;...&lt;/p&gt;
587 &lt;/chapter&gt;
588&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]589
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]590<p>The first line specifies that it's an XML document and gives useful
591information about its encoding. Then the document is a text format whose
592structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]593to be closed</strong>. XML is pedantic about this. However, if a tag is empty
594(no content), a single tag can serve as both the opening and closing tag if it
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]595ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note that,
596for example, the image tag has no content (just an attribute) and is closed by
597ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]598
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]599<p>XML can be applied sucessfully to a wide range of uses, from long term
600structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]601data encoding mechanisms like configuration file formatting (glade),
602spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
603it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]604
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]605<h2>An overview of libxml architecture</h2>
606
607<p>Libxml is made of multiple components, some of them optionals, and most of
608the block interfaces are public. The main components are:</p>
609<ul>
610 <li>an Input/Output layer</li>
611 <li>FTP and HTTP client layers (optionnal)</li>
612 <li>an Internationalization layer managing the encodings support</li>
613 <li>an URI module</li>
614 <li>the XML parser and its basic SAX interface</li>
615 <li>an HTML parser using the same SAX interface (optionnal)</li>
616 <li>a SAX tree module to build an in-memory DOM representation</li>
617 <li>a tree module to manipulate the DOM representation</li>
618 <li>a validation module using the DOM representation (optionnal)</li>
619 <li>an XPath module for global lookup in a DOM representation
620 (optionnal)</li>
621 <li>a debug module (optionnal)</li>
622</ul>
623
624<p>Graphically this gives the following:</p>
625
626<p><img src="libxml.gif" alt="a graphical view of the various"></p>
627
628<p></p>
629
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]630<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]631
632<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]633returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]634<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]635as the file name, the document type, and a <strong>children</strong> pointer
636which is the root of the document (or more exactly the first child under the
637root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]638chained in double-linked lists of siblings and with children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]639relationship. An xmlNode can also carry properties (a chain of xmlAttr
640structures). An attribute may have a value which is a list of TEXT or
641ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]642
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]643<p>Here is an example (erroneous with respect to the XML spec since there
644should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]645
646<p><img src="structure.gif" alt=" structure.gif "></p>
647
648<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]649called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]650prints them back as parsed. This is useful for detecting errors both in XML
651code and in the XML parser itself. It has an option <strong>--debug</strong>
652which prints the actual in-memory structure of the document, here is the
653result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]654<pre>DOCUMENT
655version=1.0
656standalone=true
657 ELEMENT EXAMPLE
658 ATTRIBUTE prop1
659 TEXT
660 content=gnome is great
661 ATTRIBUTE prop2
662 ENTITY_REF
663 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]664 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]665 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]666 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]667 TEXT
668 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]669 ELEMENT chapter
670 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]671 TEXT
672 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]673 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]674 TEXT
675 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]676 ELEMENT image
677 ATTRIBUTE href
678 TEXT
679 content=linus.gif
680 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]681 TEXT
682 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]683
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]684<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]685
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]686<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]687
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]688<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]689memory. In that case (and if you don't expect to save back the XML document
690loaded using libxml), it's better to use the SAX interface of libxml. SAX is a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]691<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]692application layer registers a customized set of callbacks which are called by
693the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]694
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]695<p>To get more detailed step-by-step guidance on using the SAX interface of
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]696libxml, see the <a
697href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
698documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]699Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]700
701<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
702program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]703binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]704distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]705testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]706<pre>SAX.setDocumentLocator()
707SAX.startDocument()
708SAX.getEntity(amp)
709SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
710SAX.characters( , 3)
711SAX.startElement(head)
712SAX.characters( , 4)
713SAX.startElement(title)
714SAX.characters(Welcome to Gnome, 16)
715SAX.endElement(title)
716SAX.characters( , 3)
717SAX.endElement(head)
718SAX.characters( , 3)
719SAX.startElement(chapter)
720SAX.characters( , 4)
721SAX.startElement(title)
722SAX.characters(The Linux adventure, 19)
723SAX.endElement(title)
724SAX.characters( , 4)
725SAX.startElement(p)
726SAX.characters(bla bla bla ..., 15)
727SAX.endElement(p)
728SAX.characters( , 4)
729SAX.startElement(image, href='linus.gif')
730SAX.endElement(image)
731SAX.characters( , 4)
732SAX.startElement(p)
733SAX.characters(..., 3)
734SAX.endElement(p)
735SAX.characters( , 3)
736SAX.endElement(chapter)
737SAX.characters( , 1)
738SAX.endElement(EXAMPLE)
739SAX.endDocument()</pre>
740
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]741<p>Most of the other functionalities of libxml are based on the DOM
742tree-building facility, so nearly everything up to the end of this document
743presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]744itself is built by a set of registered default callbacks, without internal
745specific interface.</p>
746
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]747<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]748
749<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]750using the XML library from the C language. It is not intended to be extensive.
751I hope the automatically generated documents will provide the completeness
752required, but as a separate set of documents. The interfaces of the XML
753library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]754interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]755
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]756<p>The <a href="html/gnome-xml-parser.html">parser interfaces for XML</a> are
757separated from the <a href="html/gnome-xml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]758interfaces</a>. Let's have a look at how the XML parser can be called:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]759
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]760<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]761
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]762<p>Usually, the first thing to do is to read an XML input. The parser accepts
763documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]764defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]765<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]766 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]767 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]768 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]769</dl>
770<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]771 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]772 <dd><p>Parse an XML document contained in a (possibly compressed)
773 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]774 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]775</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]776
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]777<p>The parser returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]778failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]779
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]780<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]781
782<p>In order for the application to keep the control when the document is been
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]783fetched (which is common for GUI based programs) libxml provides a push
784interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]785<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
786 void *user_data,
787 const char *chunk,
788 int size,
789 const char *filename);
790int xmlParseChunk (xmlParserCtxtPtr ctxt,
791 const char *chunk,
792 int size,
793 int terminate);</pre>
794
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]795<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]796<pre> FILE *f;
797
798 f = fopen(filename, "r");
799 if (f != NULL) {
800 int res, size = 1024;
801 char chars[1024];
802 xmlParserCtxtPtr ctxt;
803
804 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]805 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]806 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
807 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]808 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]809 xmlParseChunk(ctxt, chars, res, 0);
810 }
811 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]812 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]813 xmlFreeParserCtxt(ctxt);
814 }
815 }</pre>
816
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]817<p>Also note that the HTML parser embedded into libxml also has a push
818interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]819
820<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
821
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]822<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]823memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]824Reading a document without building the tree is possible using the SAX
825interfaces (see SAX.h and <a
826href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]827Henstridge's documentation</a>). Note also that the push interface can be
828limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]829<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]830
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]831<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]832
833<p>The other way to get an XML tree in memory is by building it. Basically
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]834there is a set of functions dedicated to building new elements. (These are
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]835also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of code
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]836that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]837<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]838 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]839 xmlNodePtr tree, subtree;
840
841 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]842 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
843 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
844 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
845 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]846 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]847 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]848 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
849 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
850 subtree = xmlNewChild(tree, NULL, "image", NULL);
851 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]852
853<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]854
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]855<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]856
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]857<p>Basically by <a href="html/gnome-xml-tree.html">including "tree.h"</a> your
858code has access to the internal structure of all the elements of the tree. The
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]859names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]860<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]861<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]862example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]863<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]864
865<p>points to the title element,</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]866<pre>doc-&gt;children-&gt;children-&gt;next-&gt;child-&gt;child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]867
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]868<p>points to the text node containing the chapter title "The Linux
869adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]870
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]871<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]872present before the document root, so <code>doc-&gt;children</code> may point
873to an element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]874<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]875
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]876<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]877
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]878<p>Functions are provided for reading and writing the document content. Here
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]879is an excerpt from the <a href="html/gnome-xml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]880<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]881 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
882 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]883 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
884 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]885 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]886</dl>
887<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]888 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]889 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]890 <dd><p>This function returns a pointer to new copy of the property
891 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]892 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]893</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]894
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]895<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]896elements:</p>
897<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]898 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]899 *value);</code></dt>
900 <dd><p>This function takes an "external" string and convert it to one text
901 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]902 entity references like &amp;Gnome; will be stored internally as entity
903 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]904 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]905</dl>
906<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]907 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]908 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]909 <dd><p>This function is the inverse of
910 <code>xmlStringGetNodeList()</code>. It generates a new string
911 containing the content of the text and entity nodes. Note the extra
912 argument inLine. If this argument is set to 1, the function will expand
913 entity references. For example, instead of returning the &amp;Gnome;
914 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]915 "GNU Network Object Model Environment"). Set this argument if you want
916 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]917 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]918</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]919
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]920<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]921
922<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]923<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]924 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]925 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]926 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]927 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]928</dl>
929<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]930 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]931 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]932 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]933</dl>
934<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]935 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]936 <dd><p>Saves the document to a file. In this case, the compression
937 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]938 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]939</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]940
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]941<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]942
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]943<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]944accesses. The level of compression on saves can be turned on either globally
945or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]946<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]947 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]948 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]949 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]950</dl>
951<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]952 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]953 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]954 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]955</dl>
956<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]957 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]958 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]959 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]960</dl>
961<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]962 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]963 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]964 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]965</dl>
966
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]967<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]968
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]969<p>Entities in principle are similar to simple C macros. An entity defines an
970abbreviation for a given string that you can reuse many times throughout the
971content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]972may occur frequently within a document, or to confine the change needed to a
973document to a restricted area in the internal subset of the document (at the
974beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]975<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9762 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9773 &lt;!ENTITY xml "Extensible Markup Language"&gt;
9784 ]&gt;
9795 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9806 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9817 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]982
983<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]984it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]985are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]986predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]987<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]988for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]989<strong>&amp;quot;</strong> for the character '"', and
990<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]991
992<p>One of the problems related to entities is that you may want the parser to
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]993substitute an entity's content so that you can see the replacement text in
994your application. Or you may prefer to keep entity references as such in the
995content to be able to save the document back without losing this usually
996precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]997entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]998them as saving time). The <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]999href="html/gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1000function allows you to check and change the behaviour, which is to not
1001substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1002
1003<p>Here is the DOM tree built by libxml for the previous document in the
1004default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1005<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1006DOCUMENT
1007version=1.0
1008 ELEMENT EXAMPLE
1009 TEXT
1010 content=
1011 ENTITY_REF
1012 INTERNAL_GENERAL_ENTITY xml
1013 content=Extensible Markup Language
1014 TEXT
1015 content=</pre>
1016
1017<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1018<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1019DOCUMENT
1020version=1.0
1021 ELEMENT EXAMPLE
1022 TEXT
1023 content= Extensible Markup Language</pre>
1024
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1025<p>So, entities or no entities? Basically, it depends on your use case. I
1026suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1027entities in your XML document or data if you are not willing to handle the
1028entity references elements in the DOM tree.</p>
1029
1030<p>Note that at save time libxml enforce the conversion of the predefined
1031entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1032transparently replace those with chars (i.e., it will not generate entity
1033reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1034finding them in the input).</p>
1035
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1036<p><span style="background-color: #FF0000">WARNING</span>: handling entities
1037on top of libxml SAX interface is difficult !!! If you plan to use
1038non-predefined entities in your documents, then the learning cuvre to handle
1039then using the SAX API may be long. If you plan to use complex document, I
1040strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]1041deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1042
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1043<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1044
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1045<p>The libxml library implements <a
1046href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
1047recognizing namespace contructs in the input, and does namespace lookup
1048automatically when building the DOM tree. A namespace declaration is
1049associated with an in-memory structure and all elements or attributes within
1050that namespace point to it. Hence testing the namespace is a simple and fast
1051equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1052
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1053<p>I suggest that people using libxml use a namespace, and declare it in the
1054root element of their document as the default namespace. Then they don't need
1055to use the prefix in the content but we will have a basis for future semantic
1056refinement and merging of data from different sources. This doesn't augment
1057significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1058in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1059<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
1060 &lt;elem1&gt;...&lt;/elem1&gt;
1061 &lt;elem2&gt;...&lt;/elem2&gt;
1062&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1063
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1064<p>Concerning the namespace value, this has to be an URL, but the URL doesn't
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1065have to point to any existing resource on the Web. It will bind all the
1066element and atributes with that URL. I suggest to use an URL within a domain
1067you control, and that the URL should contain some kind of version information
1068if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1069a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1070
1071<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1072version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1073and if the version information don't match something you know, warn the user
1074and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1075namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
1076same as &lt;bar:text&gt; in another document. What really matter is the URI
1077associated with the element or the attribute, not the prefix string (which is
1078just a shortcut for the full URI). In libxml element and attributes have a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1079<code>ns</code> field pointing to an xmlNs structure detailing the namespace
1080prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1081
1082<p>@@Interfaces@@</p>
1083
1084<p>@@Examples@@</p>
1085
1086<p>Usually people object using namespace in the case of validation, I object
1087this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1088so even is you plan to use or currently are using validation I strongly
1089suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1090<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1091flexible parsers. Now using namespace to mix and differentiate content coming
1092from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1093to provide ways to do this, but this may not be portable or standardized.</p>
1094
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1095<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1096
1097<p>Well what is validation and what is a DTD ?</p>
1098
1099<p>Validation is the process of checking a document against a set of
1100construction rules, a <strong>DTD</strong> (Document Type Definition) is such
1101a set of rules.</p>
1102
1103<p>The validation process and building DTDs are the two most difficult parts
1104of XML life cycle. Briefly a DTD defines all the possibles element to be
1105found within your document, what is the formal shape of your document tree (by
1106defining the allowed content of an element, either text, a regular expression
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1107for the allowed list of children, or mixed content i.e. both text and
1108children). The DTD also defines the allowed attributes for all elements and
1109the types of the attributes. For more detailed informations, I suggest to read
1110the related parts of the XML specification, the examples found under
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1111gnome-xml/test/valid/dtd and the large amount of books available on XML. The
1112dia example in gnome-xml/test/valid should be both simple and complete enough
1113to allow you to build your own.</p>
1114
1115<p>A word of warning, building a good DTD which will fit your needs of your
1116application in the long-term is far from trivial, however the extra level of
1117quality it can insure is well worth the price for some sets of applications or
1118if you already have already a DTD defined for your application field.</p>
1119
1120<p>The validation is not completely finished but in a (very IMHO) usable
1121state. Until a real validation interface is defined the way to do it is to
1122define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
1123variable to 1, this will of course be changed at some point:</p>
1124
1125<p>extern int xmlDoValidityCheckingDefaultValue;</p>
1126
1127<p>...</p>
1128
1129<p>xmlDoValidityCheckingDefaultValue = 1;</p>
1130
1131<p></p>
1132
1133<p>To handle external entities, use the function
1134<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
1135link in you HTTP/FTP/Entities database library to the standard libxml
1136core.</p>
1137
1138<p>@@interfaces@@</p>
1139
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1140<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1141
1142<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]1143Model</em> this is an API for accessing XML or HTML structured documents.
1144Native 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]1145be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]1146files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1147set of IDL (or Java) interfaces allowing to traverse and manipulate a
1148document. The DOM library will allow accessing and modifying "live" documents
1149presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1150
1151<p><img src="DOM.gif" alt=" DOM.gif "></p>
1152
1153<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1154embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1155
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1156<p>The current DOM implementation on top of libxml is the <a
1157href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
1158a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
1159Levien</a>.</p>
1160
1161<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
1162
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1163<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1164
1165<p>Here is a real size example, where the actual content of the application
1166data 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]1167a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1168storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
1169base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1170<pre>&lt;?xml version="1.0"?&gt;
1171&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
1172 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1173
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1174 &lt;gjob:Job&gt;
1175 &lt;gjob:Project ID="3"/&gt;
1176 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
1177 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1178
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1179 &lt;gjob:Update&gt;
1180 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
1181 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
1182 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
1183 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1184
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1185 &lt;gjob:Developers&gt;
1186 &lt;gjob:Developer&gt;
1187 &lt;/gjob:Developer&gt;
1188 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1189
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1190 &lt;gjob:Contact&gt;
1191 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
1192 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
1193 &lt;gjob:Company&gt;
1194 &lt;/gjob:Company&gt;
1195 &lt;gjob:Organisation&gt;
1196 &lt;/gjob:Organisation&gt;
1197 &lt;gjob:Webpage&gt;
1198 &lt;/gjob:Webpage&gt;
1199 &lt;gjob:Snailmail&gt;
1200 &lt;/gjob:Snailmail&gt;
1201 &lt;gjob:Phone&gt;
1202 &lt;/gjob:Phone&gt;
1203 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1204
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1205 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1206 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1207 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1208
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1209 &lt;gjob:Skills&gt;
1210 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1211
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1212 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1213 A GNOME based system that will allow a superuser to configure
1214 compressed and uncompressed files and/or file systems to be backed
1215 up with a supported media in the system. This should be able to
1216 perform via find commands generating a list of files that are passed
1217 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1218 or via operations performed on the filesystem itself. Email
1219 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1220 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1221
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1222 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1223
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1224 &lt;/gjob:Jobs&gt;
1225&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1226
1227<p>While loading the XML file into an internal DOM tree is a matter of calling
1228only a couple of functions, browsing the tree to gather the informations and
1229generate the internals structures is harder, and more error prone.</p>
1230
1231<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1232structure. For example, the ordering of the attributes is not significant,
1233Cthe XML specification is clear about it. It's also usually a good idea to not
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1234be dependent of the orders of the children of a given node, unless it really
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1235makes things harder. Here is some code to parse the informations for a
1236person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1237<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1238 * A person record
1239 */
1240typedef struct person {
1241 char *name;
1242 char *email;
1243 char *company;
1244 char *organisation;
1245 char *smail;
1246 char *webPage;
1247 char *phone;
1248} person, *personPtr;
1249
1250/*
1251 * And the code needed to parse it
1252 */
1253personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1254 personPtr ret = NULL;
1255
1256DEBUG("parsePerson\n");
1257 /*
1258 * allocate the struct
1259 */
1260 ret = (personPtr) malloc(sizeof(person));
1261 if (ret == NULL) {
1262 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1263 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1264 }
1265 memset(ret, 0, sizeof(person));
1266
1267 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1268 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1269 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1270 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
1271 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1272 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
1273 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1274 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1275 }
1276
1277 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1278}</pre>
1279
1280<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1281<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1282 <li>Usually a recursive parsing style is the more convenient one, XML data
1283 being by nature subject to repetitive constructs and usualy exibit highly
1284 stuctured patterns.</li>
1285 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1286 the pointer to the global XML document and the namespace reserved to the
1287 application. Document wide information are needed for example to decode
1288 entities and it's a good coding practice to define a namespace for your
1289 application set of data and test that the element and attributes you're
1290 analyzing actually pertains to your application space. This is done by a
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1291 simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1292 <li>To retrieve text and attributes value, it is suggested to use the
1293 function <em>xmlNodeListGetString</em> to gather all the text and entity
1294 reference nodes generated by the DOM output and produce an single text
1295 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1296</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1297
1298<p>Here is another piece of code used to parse another level of the
1299structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1300<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1301/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1302 * a Description for a Job
1303 */
1304typedef struct job {
1305 char *projectID;
1306 char *application;
1307 char *category;
1308 personPtr contact;
1309 int nbDevelopers;
1310 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1311} job, *jobPtr;
1312
1313/*
1314 * And the code needed to parse it
1315 */
1316jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1317 jobPtr ret = NULL;
1318
1319DEBUG("parseJob\n");
1320 /*
1321 * allocate the struct
1322 */
1323 ret = (jobPtr) malloc(sizeof(job));
1324 if (ret == NULL) {
1325 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1326 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1327 }
1328 memset(ret, 0, sizeof(job));
1329
1330 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1331 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1332 while (cur != NULL) {
1333
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1334 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
1335 ret-&gt;projectID = xmlGetProp(cur, "ID");
1336 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1337 fprintf(stderr, "Project has no ID\n");
1338 }
1339 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1340 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
1341 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1342 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
1343 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1344 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
1345 ret-&gt;contact = parsePerson(doc, ns, cur);
1346 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1347 }
1348
1349 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1350}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1351
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1352<p>One can notice that once used to it, writing this kind of code is quite
1353simple, but boring. Ultimately, it could be possble to write stubbers taking
1354either C data structure definitions, a set of XML examples or an XML DTD and
1355produce the code needed to import and export the content between C data and
1356XML storage. This is left as an exercise to the reader :-)</p>
1357
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]1358<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1359parsing example</a> as a template, it is also available with Makefile in the
1360Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1361
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1362<h2><a name="Contributi">Contributions</a></h2>
1363<ul>
Daniel Veillard851c59c2000-11-24 16:06:22 +0000[diff] [blame]1364 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1365 for libxml:
1366 <p>Website: <a
1367 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1368 <p>Download: <a
1369 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1370 </li>
1371 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1372 precompiled Windows version
1373 <p><a
1374 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1375 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1376 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1377 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1378 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1379 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1380 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1381 integrated in the distribution)</li>
1382</ul>
1383
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1384<p></p>
1385
1386<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1387
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame^]1388<p>$Id: xml.html,v 1.60 2000/11/24 16:06:22 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1389</body>
1390</html>