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gerrit-public.fairphone.software / fp2-dev / platform / external / libxml2 / 28929b2fa65567a7a7673f1ad007e7d72d7eab87 / . / doc / xml.html
blob: 58794e5021d0b70e9a48ca98e1b4104f896648e1 [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 Veillard28929b22000-11-13 18:22:49 +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 Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]55</ul>
56
57<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]58
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]59<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]60href="http://www.w3.org/XML/">XML</a> C library developped for the <a
61href="http://www.gnome.org/">Gnome</a> project. <a
62href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
63structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]64
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]65<p>Here are some key points about libxml:</p>
66<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]67 <li>Libxml exports Push and Pull type parser interfaces for both XML and
68 HTML.</li>
69 <li>Libxml can do Dtd validation at parse time, using a parsed document
70 instance, or with an arbitrary Dtd.</li>
71 <li>Libxml now includes a nearly complete <a
72 href="http://www.w3.org/TR/xpath">XPath</a> and <a
Daniel Veillard0c069222000-10-21 09:25:52 +0000[diff] [blame]73 href="http://www.w3.org/TR/xptr">XPointer</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]74 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]75 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]76 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]77 <li>Basic support for HTTP and FTP client allowing to fetch remote
78 resources</li>
79 <li>The design of modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]80 <li>The internal document repesentation is as close as possible to the <a
81 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
82 <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]83 like interface</a>; the interface is designed to be compatible with <a
84 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]85 <li>This library is released both under the <a
86 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]87 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
88 LGPL</a>. Use either at your convenience, basically this should make
89 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]90</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]91
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]92<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]93
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]94<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]95<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]96 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]97 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]98 documentation</a> automatically extracted from code comments (using <a
99 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
100 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]101 <li>Look at the documentation about <a href="encoding.html">libxml
102 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]103 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]104 examples</a> on how to use libxml.</li>
105 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
106 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
107 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108 <li>George Lebl wrote <a
109 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]110 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]111 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
112 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
113 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]114 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]115 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
116 href="http://www.levien.com/svg/">gill</a>. Check his <a
117 href="http://www.levien.com/gnome/domination.html">DOMination
118 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]119 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
120 file</a></li>
121 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
122 starting a new project using libxml you should really use the 2.x
123 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]124 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]125 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]126</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]127
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]128<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]129
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]130<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]131of fixing them in a timely fashion. The best way to report a bug is to use the
132<a href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug tracking
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]133database</a> (make sure to use the "gnome-xml" module name, not libxml or
134libxml2). I look at reports there regularly and it's good to have a reminder
135when a bug is still open. Check the <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]136href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]137and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]138
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]139<p>There is also a mailing-list <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]140href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> for libxml, with an <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]141href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]142majordomo based list, send a mail message to <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]143href="mailto:majordomo@rpmfind.net">majordomo@rpmfind.net</a> with "subscribe
144xml" in the <strong>content</strong> of the message.</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]145
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]146<p>Alternatively, you can just send the bug to the <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]147href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> list, if it's really libxml
148related I will approve it..</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]149
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]150<p>Of course, bugs reports with a suggested patch for fixing them will
151probably be processed faster.</p>
152
153<p>If you're looking for help, a quick look at <a
154href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
155provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]156questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]157documentantion</a> is not as polished as I would like (i need to learn more
158about Docbook), but it's a good starting point.</p>
159
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]160<h2><a name="help">How to help</a></h2>
161
162<p>You can help the project in various ways, the best thing to do first is to
163subscribe to the mailing-list as explained before, check the <a
164href="http://xmlsoft.org/messages/">archives </a>and the <a
165href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug
166database:</a>:</p>
167<ol>
168 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]169 <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]170 be integrated in all cases but help pinpointing portability problems
171 and</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]172 <li>provice documentation fixes (either as patches to the code comments or
173 as HTML diffs).</li>
174 <li>provide new documentations pieces (translations, examples, etc ...)</li>
175 <li>Check the TODO file and try to close one of the items</li>
176 <li>take one of the points raised in the archive or the bug database and
177 provide a fix. <a href="mailto:Daniel.Veillard@w3.org">Get in touch with
178 me </a>before to avoid synchronization problems and check that the
179 suggested fix will fit in nicely :-)</li>
180</ol>
181
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]182<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]183
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]184<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]185href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]186href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]187as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]188archive</a> or <a
189href="ftp://ftp.gnome.org/pub/GNOME/contrib/redhat/SRPMS/">RPM packages</a>.
190(NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]191href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
192href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]193packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]194
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]195<p><a name="Snapshot">Snapshot:</a></p>
196<ul>
197 <li>Code from the W3C cvs base libxml <a
198 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
199 <li>Docs, content of the web site, the list archive included <a
200 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
201</ul>
202
203<p><a name="Contribs">Contribs:</a></p>
204
205<p>I do accept external contributions, especially if compiling on another
206platform, get in touch with me to upload the package. I will keep them in the
207<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
208
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]209<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]210<ul>
211 <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]212 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]213 this base for my own development, so it's updated more regularly, but the
214 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]215 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]216 password: anonymous
217 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]218 </li>
219 <li><p>The <a
220 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]221 CVS base</a>. Check the <a
222 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
223 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]224 </li>
225</ul>
226
227<h2><a name="News">News</a></h2>
228
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]229<h3>CVS only : check the <a
230href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]231for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]232
233<p>Item floating around but not actively worked on, get in touch with me if
234you want to test those</p>
235<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame^]236 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
237 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]238 <li>working on HTML and XML links recognition layers</li>
239 <li>parsing/import of Docbook SGML docs</li>
240</ul>
241
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame^]242<h3>2.2.8: Nov 13 2000</h3>
243<ul>
244 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
245 support</li>
246 <li>Patch in conditional section handling</li>
247 <li>updated MS compiler project</li>
248 <li>fixed some XPath problems</li>
249 <li>added an URI escaping function</li>
250 <li>some other bug fixes</li>
251</ul>
252
253<h3>2.2.7: Oct 31 2000</h3>
254<ul>
255 <li>added message redirection</li>
256 <li>XPath improvements (thanks TOM !)</li>
257 <li>xmlIOParseDTD() added</li>
258 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
259 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
260</ul>
261
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]262<h3>2.2.6: Oct 25 2000:</h3>
263<ul>
264 <li>Added an hash table module, migrated a number of internal structure to
265 those</li>
266 <li>Fixed a posteriori validation problems</li>
267 <li>HTTP module cleanups</li>
268 <li>HTML parser improvements (tag errors, script/style handling, attribute
269 normalization)</li>
270 <li>coalescing of adjacent text nodes</li>
271 <li>couple of XPath bug fixes, exported the internal API</li>
272</ul>
273
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]274<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]275<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]276 <li>XPointer implementation and testsuite</li>
277 <li>Lot of XPath fixes, added variable and functions registration, more
278 tests</li>
279 <li>Portability fixes, lots of enhancements toward an easy Windows build and
280 release</li>
281 <li>Late validation fixes</li>
282 <li>Integrated a lot of contributed patches</li>
283 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]284 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]285</ul>
286
287<h3>2.2.4: Oct 1 2000:</h3>
288<ul>
289 <li>main XPath problem fixed</li>
290 <li>Integrated portability patches for Windows</li>
291 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]292</ul>
293
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]294<h3>2.2.3: Sep 17 2000</h3>
295<ul>
296 <li>bug fixes</li>
297 <li>cleanup of entity handling code</li>
298 <li>overall review of all loops in the parsers, all sprintf usage has been
299 checked too</li>
300 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
301 works smoothly now.</li>
302</ul>
303
304<h3>1.8.10: Sep 6 2000</h3>
305<ul>
306 <li>bug fix release for some Gnome projects</li>
307</ul>
308
309<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]310<ul>
311 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]312 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]313</ul>
314
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]315<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]316<ul>
317 <li>a purely bug fixes release</li>
318 <li>fixed an encoding support problem when parsing from a memory block</li>
319 <li>fixed a DOCTYPE parsing problem</li>
320 <li>removed a bug in the function allowing to override the memory allocation
321 routines</li>
322</ul>
323
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]324<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]325<ul>
326 <li>applied a lot of portability fixes</li>
327 <li>better encoding support/cleanup and saving (content is now always
328 encoded in UTF-8)</li>
329 <li>the HTML parser now correctly handles encodings</li>
330 <li>added xmlHasProp()</li>
331 <li>fixed a serious problem with &amp;#38;</li>
332 <li>propagated the fix to FTP client</li>
333 <li>cleanup, bugfixes, etc ...</li>
334 <li>Added a page about <a href="encoding.html">libxml Internationalization
335 support</a></li>
336</ul>
337
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]338<h3>1.8.9: July 9 2000</h3>
339<ul>
340 <li>fixed the spec the RPMs should be better</li>
341 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
342 rpmfind users problem</li>
343</ul>
344
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]345<h3>2.1.1: July 1 2000</h3>
346<ul>
347 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
348 <li>improvements on the HTML parser</li>
349</ul>
350
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]351<h3>2.1.0 and 1.8.8: June 29 2000</h3>
352<ul>
353 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
354 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
355 about &amp;#38; charref parsing</li>
356 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
357 also contains numerous fixes and enhancements:
358 <ul>
359 <li>added xmlStopParser() to stop parsing</li>
360 <li>improved a lot parsing speed when there is large CDATA blocs</li>
361 <li>includes XPath patches provided by Picdar Technology</li>
362 <li>tried to fix as much as possible DtD validation and namespace
363 related problems</li>
364 <li>output to a given encoding has been added/tested</li>
365 <li>lot of various fixes</li>
366 </ul>
367 </li>
368</ul>
369
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]370<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]371<ul>
372 <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]373 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
374 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
375 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]376 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]377 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]378 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]379 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]380 <pre>#include "xxx.h"</pre>
381 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]382 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
383 <li>the memory allocation routines used by libxml can now be overloaded
384 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]385 <li>The previously CVS only tool tester has been renamed
386 <strong>xmllint</strong> and is now installed as part of the libxml2
387 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]388 <li>The I/O interface has been revamped. There is now ways to plug in
389 specific I/O modules, either at the URI scheme detection level using
390 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
391 parser context using xmlCreateIOParserCtxt()</li>
392 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
393 number of the libxml module in use</li>
394 <li>a number of optional features of libxml can now be excluded at configure
395 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]396</ul>
397
398<h3>2.0.0beta: Mar 14 2000</h3>
399<ul>
400 <li>This is a first Beta release of libxml version 2</li>
401 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
402 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
403 tar and RPMs</li>
404 <li>This version is now the head in the Gnome CVS base, the old one is
405 available under the tag LIB_XML_1_X</li>
406 <li>This includes a very large set of changes. Froma programmatic point of
407 view applications should not have to be modified too much, check the <a
408 href="upgrade.html">upgrade page</a></li>
409 <li>Some interfaces may changes (especially a bit about encoding).</li>
410 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]411 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]412 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
413 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]414 <li>Better handling of entities, especially well formedness checking and
415 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]416 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]417 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]418 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
419 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]420 </ul>
421 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]422 <li>Serious progress were made toward compliance, <a
423 href="conf/result.html">here are the result of the test</a> against the
424 OASIS testsuite (except the japanese tests since I don't support that
425 encoding yet). This URL is rebuilt every couple of hours using the CVS
426 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]427</ul>
428
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]429<h3>1.8.7: Mar 6 2000</h3>
430<ul>
431 <li>This is a bug fix release:</li>
432 <li>It is possible to disable the ignorable blanks heuristic used by
433 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
434 that for adherence to XML spec, this behaviour will be disabled by default
435 in 2.x . The same function will allow to keep compatibility for old
436 code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]437 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
438 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]439 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
440 compilation on some platforms has been fixed</li>
441 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
442 URIs</li>
443</ul>
444
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]445<h3>1.8.6: Jan 31 2000</h3>
446<ul>
447 <li>added a nanoFTP transport module, debugged until the new version of <a
448 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
449 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]450</ul>
451
452<h3>1.8.5: Jan 21 2000</h3>
453<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]454 <li>adding APIs to parse a well balanced chunk of XML (production <a
455 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
456 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]457 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]458 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
459 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]460 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
461 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]462</ul>
463
464<h3>1.8.4: Jan 13 2000</h3>
465<ul>
466 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
467 <li>all exit() call should have been removed from libxml</li>
468 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
469 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]470</ul>
471
472<h3>1.8.3: Jan 5 2000</h3>
473<ul>
474 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]475 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]476 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]477 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]478 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
479 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]480 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]481 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]482 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]483</ul>
484
485<h3>1.8.2: Dec 21 1999</h3>
486<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]487 <li>I got another problem with includes and C++, I hope this issue is fixed
488 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]489 <li>Added a few tree modification functions: xmlReplaceNode,
490 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
491 xmlDocSetRootElement</li>
492 <li>Tried to improve the HTML output with help from <a
493 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]494</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]495
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]496<h3>1.8.1: Dec 18 1999</h3>
497<ul>
498 <li>various patches to avoid troubles when using libxml with C++ compilers
499 the "namespace" keyword and C escaping in include files</li>
500 <li>a problem in one of the core macros IS_CHAR was corrected</li>
501 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
502 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]503 <li>fixed a posteriori validation (validation after parsing, or by using a
504 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]505 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]506</ul>
507
508<h3>1.8.0: Dec 12 1999</h3>
509<ul>
510 <li>cleanup, especially memory wise</li>
511 <li>the parser should be more reliable, especially the HTML one, it should
512 not crash, whatever the input !</li>
513 <li>Integrated various patches, especially a speedup improvement for large
514 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
515 configure with --with-buffers to enable them.</li>
516 <li>attribute normalization, oops should have been added long ago !</li>
517 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
518 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]519</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]520
521<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]522<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]523 <li>Lots of HTML improvement</li>
524 <li>Fixed some errors when saving both XML and HTML</li>
525 <li>More examples, the regression tests should now look clean</li>
526 <li>Fixed a bug with contiguous charref</li>
527</ul>
528
529<h3>1.7.3: Sep 29 1999</h3>
530<ul>
531 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]532 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]533 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]534</ul>
535
536<h3>1.7.1: Sep 24 1999</h3>
537<ul>
538 <li>The basic type for strings manipulated by libxml has been renamed in
539 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
540 is that CHAR was conflicting with a predefined type on Windows. However on
541 non WIN32 environment, compatibility is provided by the way of a
542 <strong>#define </strong>.</li>
543 <li>Changed another error : the use of a structure field called errno, and
544 leading to troubles on platforms where it's a macro</li>
545</ul>
546
547<h3>1.7.0: sep 23 1999</h3>
548<ul>
549 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]550 href="html/gnome-xml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]551 <li>Added an errno to report errors by another mean than a simple printf
552 like callback</li>
553 <li>Finished ID/IDREF support and checking when validation</li>
554 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]555 href="html/gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]556 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
557 implementation</li>
558 <li>Added an HTML parser front-end</li>
559</ul>
560
561<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]562
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]563<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]564markup-based structured documents. Here is <a name="example">an example XML
565document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]566<pre>&lt;?xml version="1.0"?&gt;
567&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
568 &lt;head&gt;
569 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
570 &lt;/head&gt;
571 &lt;chapter&gt;
572 &lt;title&gt;The Linux adventure&lt;/title&gt;
573 &lt;p&gt;bla bla bla ...&lt;/p&gt;
574 &lt;image href="linus.gif"/&gt;
575 &lt;p&gt;...&lt;/p&gt;
576 &lt;/chapter&gt;
577&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]578
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]579<p>The first line specifies that it's an XML document and gives useful
580information about its encoding. Then the document is a text format whose
581structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]582to be closed</strong>. XML is pedantic about this. However, if a tag is empty
583(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]584ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note that,
585for example, the image tag has no content (just an attribute) and is closed by
586ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]587
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]588<p>XML can be applied sucessfully to a wide range of uses, from long term
589structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]590data encoding mechanisms like configuration file formatting (glade),
591spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
592it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]593
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]594<h2>An overview of libxml architecture</h2>
595
596<p>Libxml is made of multiple components, some of them optionals, and most of
597the block interfaces are public. The main components are:</p>
598<ul>
599 <li>an Input/Output layer</li>
600 <li>FTP and HTTP client layers (optionnal)</li>
601 <li>an Internationalization layer managing the encodings support</li>
602 <li>an URI module</li>
603 <li>the XML parser and its basic SAX interface</li>
604 <li>an HTML parser using the same SAX interface (optionnal)</li>
605 <li>a SAX tree module to build an in-memory DOM representation</li>
606 <li>a tree module to manipulate the DOM representation</li>
607 <li>a validation module using the DOM representation (optionnal)</li>
608 <li>an XPath module for global lookup in a DOM representation
609 (optionnal)</li>
610 <li>a debug module (optionnal)</li>
611</ul>
612
613<p>Graphically this gives the following:</p>
614
615<p><img src="libxml.gif" alt="a graphical view of the various"></p>
616
617<p></p>
618
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]619<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]620
621<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]622returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]623<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]624as the file name, the document type, and a <strong>children</strong> pointer
625which is the root of the document (or more exactly the first child under the
626root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]627chained in double-linked lists of siblings and with children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]628relationship. An xmlNode can also carry properties (a chain of xmlAttr
629structures). An attribute may have a value which is a list of TEXT or
630ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]631
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]632<p>Here is an example (erroneous with respect to the XML spec since there
633should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]634
635<p><img src="structure.gif" alt=" structure.gif "></p>
636
637<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]638called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]639prints them back as parsed. This is useful for detecting errors both in XML
640code and in the XML parser itself. It has an option <strong>--debug</strong>
641which prints the actual in-memory structure of the document, here is the
642result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]643<pre>DOCUMENT
644version=1.0
645standalone=true
646 ELEMENT EXAMPLE
647 ATTRIBUTE prop1
648 TEXT
649 content=gnome is great
650 ATTRIBUTE prop2
651 ENTITY_REF
652 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]653 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]654 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]655 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]656 TEXT
657 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]658 ELEMENT chapter
659 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]660 TEXT
661 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]662 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]663 TEXT
664 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]665 ELEMENT image
666 ATTRIBUTE href
667 TEXT
668 content=linus.gif
669 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]670 TEXT
671 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]672
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]673<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]674
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]675<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]676
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]677<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]678memory. In that case (and if you don't expect to save back the XML document
679loaded 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]680<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]681application layer registers a customized set of callbacks which are called by
682the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]683
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]684<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]685libxml, see the <a
686href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
687documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]688Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]689
690<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
691program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]692binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]693distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]694testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]695<pre>SAX.setDocumentLocator()
696SAX.startDocument()
697SAX.getEntity(amp)
698SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
699SAX.characters( , 3)
700SAX.startElement(head)
701SAX.characters( , 4)
702SAX.startElement(title)
703SAX.characters(Welcome to Gnome, 16)
704SAX.endElement(title)
705SAX.characters( , 3)
706SAX.endElement(head)
707SAX.characters( , 3)
708SAX.startElement(chapter)
709SAX.characters( , 4)
710SAX.startElement(title)
711SAX.characters(The Linux adventure, 19)
712SAX.endElement(title)
713SAX.characters( , 4)
714SAX.startElement(p)
715SAX.characters(bla bla bla ..., 15)
716SAX.endElement(p)
717SAX.characters( , 4)
718SAX.startElement(image, href='linus.gif')
719SAX.endElement(image)
720SAX.characters( , 4)
721SAX.startElement(p)
722SAX.characters(..., 3)
723SAX.endElement(p)
724SAX.characters( , 3)
725SAX.endElement(chapter)
726SAX.characters( , 1)
727SAX.endElement(EXAMPLE)
728SAX.endDocument()</pre>
729
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]730<p>Most of the other functionalities of libxml are based on the DOM
731tree-building facility, so nearly everything up to the end of this document
732presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]733itself is built by a set of registered default callbacks, without internal
734specific interface.</p>
735
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]736<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]737
738<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]739using the XML library from the C language. It is not intended to be extensive.
740I hope the automatically generated documents will provide the completeness
741required, but as a separate set of documents. The interfaces of the XML
742library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]743interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]744
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]745<p>The <a href="html/gnome-xml-parser.html">parser interfaces for XML</a> are
746separated from the <a href="html/gnome-xml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]747interfaces</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]748
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]749<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]750
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]751<p>Usually, the first thing to do is to read an XML input. The parser accepts
752documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]753defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]754<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]755 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]756 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]757 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]758</dl>
759<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]760 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]761 <dd><p>Parse an XML document contained in a (possibly compressed)
762 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]763 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]764</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]765
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]766<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]767failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]768
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]769<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]770
771<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]772fetched (which is common for GUI based programs) libxml provides a push
773interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]774<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
775 void *user_data,
776 const char *chunk,
777 int size,
778 const char *filename);
779int xmlParseChunk (xmlParserCtxtPtr ctxt,
780 const char *chunk,
781 int size,
782 int terminate);</pre>
783
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]784<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]785<pre> FILE *f;
786
787 f = fopen(filename, "r");
788 if (f != NULL) {
789 int res, size = 1024;
790 char chars[1024];
791 xmlParserCtxtPtr ctxt;
792
793 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]794 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]795 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
796 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]797 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]798 xmlParseChunk(ctxt, chars, res, 0);
799 }
800 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]801 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]802 xmlFreeParserCtxt(ctxt);
803 }
804 }</pre>
805
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]806<p>Also note that the HTML parser embedded into libxml also has a push
807interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]808
809<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
810
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]811<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]812memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]813Reading a document without building the tree is possible using the SAX
814interfaces (see SAX.h and <a
815href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]816Henstridge's documentation</a>). Note also that the push interface can be
817limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]818<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]819
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]820<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]821
822<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]823there is a set of functions dedicated to building new elements. (These are
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]824also 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]825that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]826<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]827 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]828 xmlNodePtr tree, subtree;
829
830 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]831 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
832 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
833 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
834 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]835 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]836 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]837 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
838 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
839 subtree = xmlNewChild(tree, NULL, "image", NULL);
840 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]841
842<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]843
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]844<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]845
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]846<p>Basically by <a href="html/gnome-xml-tree.html">including "tree.h"</a> your
847code has access to the internal structure of all the elements of the tree. The
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]848names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]849<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]850<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]851example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]852<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]853
854<p>points to the title element,</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]855<pre>doc-&gt;children-&gt;children-&gt;next-&gt;child-&gt;child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]856
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]857<p>points to the text node containing the chapter title "The Linux
858adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]859
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]860<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]861present before the document root, so <code>doc-&gt;children</code> may point
862to an element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]863<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]864
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]865<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]866
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]867<p>Functions are provided for reading and writing the document content. Here
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]868is 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]869<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]870 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
871 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]872 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
873 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]874 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]875</dl>
876<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]877 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]878 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]879 <dd><p>This function returns a pointer to new copy of the property
880 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]881 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]882</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]883
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]884<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]885elements:</p>
886<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]887 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]888 *value);</code></dt>
889 <dd><p>This function takes an "external" string and convert it to one text
890 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]891 entity references like &amp;Gnome; will be stored internally as entity
892 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]893 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]894</dl>
895<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]896 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]897 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]898 <dd><p>This function is the inverse of
899 <code>xmlStringGetNodeList()</code>. It generates a new string
900 containing the content of the text and entity nodes. Note the extra
901 argument inLine. If this argument is set to 1, the function will expand
902 entity references. For example, instead of returning the &amp;Gnome;
903 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]904 "GNU Network Object Model Environment"). Set this argument if you want
905 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]906 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]907</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]908
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]909<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]910
911<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]912<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]913 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]914 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]915 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]916 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]917</dl>
918<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]919 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]920 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]921 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]922</dl>
923<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]924 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]925 <dd><p>Saves the document to a file. In this case, the compression
926 interface is triggered if it has been turned on.</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>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]929
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]930<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]931
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]932<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]933accesses. The level of compression on saves can be turned on either globally
934or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]935<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]936 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]937 <dd><p>Gets the document compression ratio (0-9).</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>
940<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]941 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]942 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]943 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]944</dl>
945<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]946 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]947 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]948 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]949</dl>
950<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]951 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]952 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]953 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]954</dl>
955
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]956<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]957
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]958<p>Entities in principle are similar to simple C macros. An entity defines an
959abbreviation for a given string that you can reuse many times throughout the
960content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]961may occur frequently within a document, or to confine the change needed to a
962document to a restricted area in the internal subset of the document (at the
963beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]964<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9652 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9663 &lt;!ENTITY xml "Extensible Markup Language"&gt;
9674 ]&gt;
9685 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9696 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9707 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]971
972<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]973it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]974are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]975predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]976<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]977for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]978<strong>&amp;quot;</strong> for the character '"', and
979<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]980
981<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]982substitute an entity's content so that you can see the replacement text in
983your application. Or you may prefer to keep entity references as such in the
984content to be able to save the document back without losing this usually
985precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]986entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]987them as saving time). The <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]988href="html/gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]989function allows you to check and change the behaviour, which is to not
990substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]991
992<p>Here is the DOM tree built by libxml for the previous document in the
993default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]994<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]995DOCUMENT
996version=1.0
997 ELEMENT EXAMPLE
998 TEXT
999 content=
1000 ENTITY_REF
1001 INTERNAL_GENERAL_ENTITY xml
1002 content=Extensible Markup Language
1003 TEXT
1004 content=</pre>
1005
1006<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1007<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1008DOCUMENT
1009version=1.0
1010 ELEMENT EXAMPLE
1011 TEXT
1012 content= Extensible Markup Language</pre>
1013
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1014<p>So, entities or no entities? Basically, it depends on your use case. I
1015suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1016entities in your XML document or data if you are not willing to handle the
1017entity references elements in the DOM tree.</p>
1018
1019<p>Note that at save time libxml enforce the conversion of the predefined
1020entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1021transparently replace those with chars (i.e., it will not generate entity
1022reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1023finding them in the input).</p>
1024
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1025<p><span style="background-color: #FF0000">WARNING</span>: handling entities
1026on top of libxml SAX interface is difficult !!! If you plan to use
1027non-predefined entities in your documents, then the learning cuvre to handle
1028then using the SAX API may be long. If you plan to use complex document, I
1029strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]1030deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1031
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1032<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1033
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1034<p>The libxml library implements <a
1035href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
1036recognizing namespace contructs in the input, and does namespace lookup
1037automatically when building the DOM tree. A namespace declaration is
1038associated with an in-memory structure and all elements or attributes within
1039that namespace point to it. Hence testing the namespace is a simple and fast
1040equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1041
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1042<p>I suggest that people using libxml use a namespace, and declare it in the
1043root element of their document as the default namespace. Then they don't need
1044to use the prefix in the content but we will have a basis for future semantic
1045refinement and merging of data from different sources. This doesn't augment
1046significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1047in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1048<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
1049 &lt;elem1&gt;...&lt;/elem1&gt;
1050 &lt;elem2&gt;...&lt;/elem2&gt;
1051&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1052
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1053<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]1054have to point to any existing resource on the Web. It will bind all the
1055element and atributes with that URL. I suggest to use an URL within a domain
1056you control, and that the URL should contain some kind of version information
1057if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1058a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1059
1060<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1061version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1062and if the version information don't match something you know, warn the user
1063and 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]1064namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
1065same as &lt;bar:text&gt; in another document. What really matter is the URI
1066associated with the element or the attribute, not the prefix string (which is
1067just a shortcut for the full URI). In libxml element and attributes have a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1068<code>ns</code> field pointing to an xmlNs structure detailing the namespace
1069prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1070
1071<p>@@Interfaces@@</p>
1072
1073<p>@@Examples@@</p>
1074
1075<p>Usually people object using namespace in the case of validation, I object
1076this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1077so even is you plan to use or currently are using validation I strongly
1078suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1079<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1080flexible parsers. Now using namespace to mix and differentiate content coming
1081from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1082to provide ways to do this, but this may not be portable or standardized.</p>
1083
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1084<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1085
1086<p>Well what is validation and what is a DTD ?</p>
1087
1088<p>Validation is the process of checking a document against a set of
1089construction rules, a <strong>DTD</strong> (Document Type Definition) is such
1090a set of rules.</p>
1091
1092<p>The validation process and building DTDs are the two most difficult parts
1093of XML life cycle. Briefly a DTD defines all the possibles element to be
1094found within your document, what is the formal shape of your document tree (by
1095defining the allowed content of an element, either text, a regular expression
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1096for the allowed list of children, or mixed content i.e. both text and
1097children). The DTD also defines the allowed attributes for all elements and
1098the types of the attributes. For more detailed informations, I suggest to read
1099the related parts of the XML specification, the examples found under
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1100gnome-xml/test/valid/dtd and the large amount of books available on XML. The
1101dia example in gnome-xml/test/valid should be both simple and complete enough
1102to allow you to build your own.</p>
1103
1104<p>A word of warning, building a good DTD which will fit your needs of your
1105application in the long-term is far from trivial, however the extra level of
1106quality it can insure is well worth the price for some sets of applications or
1107if you already have already a DTD defined for your application field.</p>
1108
1109<p>The validation is not completely finished but in a (very IMHO) usable
1110state. Until a real validation interface is defined the way to do it is to
1111define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
1112variable to 1, this will of course be changed at some point:</p>
1113
1114<p>extern int xmlDoValidityCheckingDefaultValue;</p>
1115
1116<p>...</p>
1117
1118<p>xmlDoValidityCheckingDefaultValue = 1;</p>
1119
1120<p></p>
1121
1122<p>To handle external entities, use the function
1123<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
1124link in you HTTP/FTP/Entities database library to the standard libxml
1125core.</p>
1126
1127<p>@@interfaces@@</p>
1128
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1129<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1130
1131<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]1132Model</em> this is an API for accessing XML or HTML structured documents.
1133Native 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]1134be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]1135files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1136set of IDL (or Java) interfaces allowing to traverse and manipulate a
1137document. The DOM library will allow accessing and modifying "live" documents
1138presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1139
1140<p><img src="DOM.gif" alt=" DOM.gif "></p>
1141
1142<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1143embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1144
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1145<p>The current DOM implementation on top of libxml is the <a
1146href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
1147a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
1148Levien</a>.</p>
1149
1150<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
1151
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1152<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1153
1154<p>Here is a real size example, where the actual content of the application
1155data 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]1156a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1157storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
1158base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1159<pre>&lt;?xml version="1.0"?&gt;
1160&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
1161 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1162
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1163 &lt;gjob:Job&gt;
1164 &lt;gjob:Project ID="3"/&gt;
1165 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
1166 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1167
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1168 &lt;gjob:Update&gt;
1169 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
1170 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
1171 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
1172 &lt;/gjob:Update&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:Developers&gt;
1175 &lt;gjob:Developer&gt;
1176 &lt;/gjob:Developer&gt;
1177 &lt;/gjob:Developers&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:Contact&gt;
1180 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
1181 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
1182 &lt;gjob:Company&gt;
1183 &lt;/gjob:Company&gt;
1184 &lt;gjob:Organisation&gt;
1185 &lt;/gjob:Organisation&gt;
1186 &lt;gjob:Webpage&gt;
1187 &lt;/gjob:Webpage&gt;
1188 &lt;gjob:Snailmail&gt;
1189 &lt;/gjob:Snailmail&gt;
1190 &lt;gjob:Phone&gt;
1191 &lt;/gjob:Phone&gt;
1192 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1193
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1194 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1195 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1196 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1197
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1198 &lt;gjob:Skills&gt;
1199 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1200
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1201 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1202 A GNOME based system that will allow a superuser to configure
1203 compressed and uncompressed files and/or file systems to be backed
1204 up with a supported media in the system. This should be able to
1205 perform via find commands generating a list of files that are passed
1206 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1207 or via operations performed on the filesystem itself. Email
1208 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1209 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1210
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1211 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1212
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1213 &lt;/gjob:Jobs&gt;
1214&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1215
1216<p>While loading the XML file into an internal DOM tree is a matter of calling
1217only a couple of functions, browsing the tree to gather the informations and
1218generate the internals structures is harder, and more error prone.</p>
1219
1220<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1221structure. For example, the ordering of the attributes is not significant,
1222Cthe 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]1223be dependent of the orders of the children of a given node, unless it really
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1224makes things harder. Here is some code to parse the informations for a
1225person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1226<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1227 * A person record
1228 */
1229typedef struct person {
1230 char *name;
1231 char *email;
1232 char *company;
1233 char *organisation;
1234 char *smail;
1235 char *webPage;
1236 char *phone;
1237} person, *personPtr;
1238
1239/*
1240 * And the code needed to parse it
1241 */
1242personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1243 personPtr ret = NULL;
1244
1245DEBUG("parsePerson\n");
1246 /*
1247 * allocate the struct
1248 */
1249 ret = (personPtr) malloc(sizeof(person));
1250 if (ret == NULL) {
1251 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1252 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1253 }
1254 memset(ret, 0, sizeof(person));
1255
1256 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1257 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1258 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1259 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
1260 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1261 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
1262 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1263 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1264 }
1265
1266 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1267}</pre>
1268
1269<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1270<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1271 <li>Usually a recursive parsing style is the more convenient one, XML data
1272 being by nature subject to repetitive constructs and usualy exibit highly
1273 stuctured patterns.</li>
1274 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1275 the pointer to the global XML document and the namespace reserved to the
1276 application. Document wide information are needed for example to decode
1277 entities and it's a good coding practice to define a namespace for your
1278 application set of data and test that the element and attributes you're
1279 analyzing actually pertains to your application space. This is done by a
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1280 simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1281 <li>To retrieve text and attributes value, it is suggested to use the
1282 function <em>xmlNodeListGetString</em> to gather all the text and entity
1283 reference nodes generated by the DOM output and produce an single text
1284 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1285</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1286
1287<p>Here is another piece of code used to parse another level of the
1288structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1289<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1290/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1291 * a Description for a Job
1292 */
1293typedef struct job {
1294 char *projectID;
1295 char *application;
1296 char *category;
1297 personPtr contact;
1298 int nbDevelopers;
1299 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1300} job, *jobPtr;
1301
1302/*
1303 * And the code needed to parse it
1304 */
1305jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1306 jobPtr ret = NULL;
1307
1308DEBUG("parseJob\n");
1309 /*
1310 * allocate the struct
1311 */
1312 ret = (jobPtr) malloc(sizeof(job));
1313 if (ret == NULL) {
1314 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1315 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1316 }
1317 memset(ret, 0, sizeof(job));
1318
1319 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1320 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1321 while (cur != NULL) {
1322
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1323 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
1324 ret-&gt;projectID = xmlGetProp(cur, "ID");
1325 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1326 fprintf(stderr, "Project has no ID\n");
1327 }
1328 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1329 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
1330 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1331 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
1332 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1333 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
1334 ret-&gt;contact = parsePerson(doc, ns, cur);
1335 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1336 }
1337
1338 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1339}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1340
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1341<p>One can notice that once used to it, writing this kind of code is quite
1342simple, but boring. Ultimately, it could be possble to write stubbers taking
1343either C data structure definitions, a set of XML examples or an XML DTD and
1344produce the code needed to import and export the content between C data and
1345XML storage. This is left as an exercise to the reader :-)</p>
1346
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]1347<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1348parsing example</a> as a template, it is also available with Makefile in the
1349Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1350
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1351<h2><a name="Contributi">Contributions</a></h2>
1352<ul>
1353 <li><a href="mailto:ari@btigate.com">Ari Johnson</a> provides a C++ wrapper
1354 for libxml:
1355 <p>Website: <a
1356 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1357 <p>Download: <a
1358 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1359 </li>
1360 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1361 precompiled Windows version
1362 <p><a
1363 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1364 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1365 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1366 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1367 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1368 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1369 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1370 integrated in the distribution)</li>
1371</ul>
1372
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1373<p></p>
1374
1375<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1376
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame^]1377<p>$Id: xml.html,v 1.57 2000/10/25 13:32:38 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1378</body>
1379</html>