Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / libxml2 / 851c59c20ef119c5f3deece82c8991e90069b730 / . / doc / xml.html
blob: 9a85675eb818fcd129150a95bec5e513bb0572b7 [file] [log] [blame]
Daniel Veillard300f7d62000-11-24 13:04:04 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillard300f7d62000-11-24 13:04:04 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V4.1">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]11<p><a href="http://www.gnome.org/"><img src="smallfootonly.gif"
12alt="Gnome Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png"
13alt="W3C Logo"></a></p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]14
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]15<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]16
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17<h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2>
18
19<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]20<ul>
21 <li><a href="#Introducti">Introduction</a></li>
22 <li><a href="#Documentat">Documentation</a></li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]23 <li><a href="#Reporting">Reporting bugs and getting help</a></li>
24 <li><a href="#help">how to help</a></li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]25 <li><a href="#Downloads">Downloads</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]26 <li><a href="#News">News</a></li>
27 <li><a href="#XML">XML</a></li>
28 <li><a href="#tree">The tree output</a></li>
29 <li><a href="#interface">The SAX interface</a></li>
30 <li><a href="#library">The XML library interfaces</a>
31 <ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]32 <li><a href="#Invoking">Invoking the parser: the pull way</a></li>
33 <li><a href="#Invoking">Invoking the parser: the push way</a></li>
34 <li><a href="#Invoking2">Invoking the parser: the SAX interface</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]35 <li><a href="#Building">Building a tree from scratch</a></li>
36 <li><a href="#Traversing">Traversing the tree</a></li>
37 <li><a href="#Modifying">Modifying the tree</a></li>
38 <li><a href="#Saving">Saving the tree</a></li>
39 <li><a href="#Compressio">Compression</a></li>
40 </ul>
41 </li>
42 <li><a href="#Entities">Entities or no entities</a></li>
43 <li><a href="#Namespaces">Namespaces</a></li>
44 <li><a href="#Validation">Validation</a></li>
45 <li><a href="#Principles">DOM principles</a></li>
46 <li><a href="#real">A real example</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]47 <li><a href="#Contributi">Contributions</a></li>
48</ul>
49
50<p>Separate documents:</p>
51<ul>
52 <li><a href="upgrade.html">upgrade instructions for migrating to
53 libxml2</a></li>
54 <li><a href="encoding.html">libxml Internationalization support</a></li>
55 <li><a href="xmlio.html">libxml Input/Output interfaces</a></li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]56 <li><a href="xmlmem.html">libxml Memory interfaces</a></li>
Daniel Veillard300f7d62000-11-24 13:04:04 +0000[diff] [blame]57 <li><a href="xmldtd.html">a short introduction about DTDs and
58 libxml</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]59</ul>
60
61<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]62
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]63<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]64href="http://www.w3.org/XML/">XML</a> C library developped for the <a
65href="http://www.gnome.org/">Gnome</a> project. <a
66href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
67structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]68
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]69<p>Here are some key points about libxml:</p>
70<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]71 <li>Libxml exports Push and Pull type parser interfaces for both XML and
72 HTML.</li>
73 <li>Libxml can do Dtd validation at parse time, using a parsed document
74 instance, or with an arbitrary Dtd.</li>
75 <li>Libxml now includes a nearly complete <a
76 href="http://www.w3.org/TR/xpath">XPath</a> and <a
Daniel Veillard0c069222000-10-21 09:25:52 +0000[diff] [blame]77 href="http://www.w3.org/TR/xptr">XPointer</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]78 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]79 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]80 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]81 <li>Basic support for HTTP and FTP client allowing to fetch remote
82 resources</li>
83 <li>The design of modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]84 <li>The internal document repesentation is as close as possible to the <a
85 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
86 <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]87 like interface</a>; the interface is designed to be compatible with <a
88 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]89 <li>This library is released both under the <a
90 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]91 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
92 LGPL</a>. Use either at your convenience, basically this should make
93 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]94</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]95
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]96<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]97
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]98<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]99<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]100 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]101 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]102 documentation</a> automatically extracted from code comments (using <a
103 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
104 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]105 <li>Look at the documentation about <a href="encoding.html">libxml
106 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]107 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]108 examples</a> on how to use libxml.</li>
109 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
110 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
111 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]112 <li>George Lebl wrote <a
113 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]114 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]115 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
116 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
117 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]118 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]119 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
120 href="http://www.levien.com/svg/">gill</a>. Check his <a
121 href="http://www.levien.com/gnome/domination.html">DOMination
122 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]123 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
124 file</a></li>
125 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
126 starting a new project using libxml you should really use the 2.x
127 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]128 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]129 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]130</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]131
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]132<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]133
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]134<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]135of fixing them in a timely fashion. The best way to report a bug is to use the
136<a href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug tracking
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]137database</a> (make sure to use the "gnome-xml" module name, not libxml or
138libxml2). I look at reports there regularly and it's good to have a reminder
139when a bug is still open. Check the <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]140href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]141and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]142
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]143<p>There is also a mailing-list <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]144href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> for libxml, with an <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]145href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]146majordomo based list, send a mail message to <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]147href="mailto:majordomo@rpmfind.net">majordomo@rpmfind.net</a> with "subscribe
148xml" in the <strong>content</strong> of the message.</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]149
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]150<p>Alternatively, you can just send the bug to the <a
Daniel Veillardf121ab72000-08-29 23:40:42 +0000[diff] [blame]151href="mailto:xml@rpmfind.net">xml@rpmfind.net</a> list, if it's really libxml
152related I will approve it..</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]153
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]154<p>Of course, bugs reports with a suggested patch for fixing them will
155probably be processed faster.</p>
156
157<p>If you're looking for help, a quick look at <a
158href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
159provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]160questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]161documentantion</a> is not as polished as I would like (i need to learn more
162about Docbook), but it's a good starting point.</p>
163
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]164<h2><a name="help">How to help</a></h2>
165
166<p>You can help the project in various ways, the best thing to do first is to
167subscribe to the mailing-list as explained before, check the <a
168href="http://xmlsoft.org/messages/">archives </a>and the <a
169href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug
170database:</a>:</p>
171<ol>
172 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]173 <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]174 be integrated in all cases but help pinpointing portability problems
175 and</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]176 <li>provice documentation fixes (either as patches to the code comments or
177 as HTML diffs).</li>
178 <li>provide new documentations pieces (translations, examples, etc ...)</li>
179 <li>Check the TODO file and try to close one of the items</li>
180 <li>take one of the points raised in the archive or the bug database and
181 provide a fix. <a href="mailto:Daniel.Veillard@w3.org">Get in touch with
182 me </a>before to avoid synchronization problems and check that the
183 suggested fix will fit in nicely :-)</li>
184</ol>
185
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]186<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]187
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]188<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]189href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]190href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]191as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]192archive</a> or <a
193href="ftp://ftp.gnome.org/pub/GNOME/contrib/redhat/SRPMS/">RPM packages</a>.
194(NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]195href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
196href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]197packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]198
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]199<p><a name="Snapshot">Snapshot:</a></p>
200<ul>
201 <li>Code from the W3C cvs base libxml <a
202 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
203 <li>Docs, content of the web site, the list archive included <a
204 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
205</ul>
206
207<p><a name="Contribs">Contribs:</a></p>
208
209<p>I do accept external contributions, especially if compiling on another
210platform, get in touch with me to upload the package. I will keep them in the
211<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
212
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]213<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]214<ul>
215 <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]216 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]217 this base for my own development, so it's updated more regularly, but the
218 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]219 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]220 password: anonymous
221 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]222 </li>
223 <li><p>The <a
224 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]225 CVS base</a>. Check the <a
226 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
227 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]228 </li>
229</ul>
230
231<h2><a name="News">News</a></h2>
232
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]233<h3>CVS only : check the <a
234href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]235for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]236
237<p>Item floating around but not actively worked on, get in touch with me if
238you want to test those</p>
239<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]240 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
241 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]242 <li>working on HTML and XML links recognition layers</li>
243 <li>parsing/import of Docbook SGML docs</li>
244</ul>
245
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]246<h3>2.2.8: Nov 13 2000</h3>
247<ul>
248 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
249 support</li>
250 <li>Patch in conditional section handling</li>
251 <li>updated MS compiler project</li>
252 <li>fixed some XPath problems</li>
253 <li>added an URI escaping function</li>
254 <li>some other bug fixes</li>
255</ul>
256
257<h3>2.2.7: Oct 31 2000</h3>
258<ul>
259 <li>added message redirection</li>
260 <li>XPath improvements (thanks TOM !)</li>
261 <li>xmlIOParseDTD() added</li>
262 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
263 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
264</ul>
265
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]266<h3>2.2.6: Oct 25 2000:</h3>
267<ul>
268 <li>Added an hash table module, migrated a number of internal structure to
269 those</li>
270 <li>Fixed a posteriori validation problems</li>
271 <li>HTTP module cleanups</li>
272 <li>HTML parser improvements (tag errors, script/style handling, attribute
273 normalization)</li>
274 <li>coalescing of adjacent text nodes</li>
275 <li>couple of XPath bug fixes, exported the internal API</li>
276</ul>
277
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]278<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]279<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]280 <li>XPointer implementation and testsuite</li>
281 <li>Lot of XPath fixes, added variable and functions registration, more
282 tests</li>
283 <li>Portability fixes, lots of enhancements toward an easy Windows build and
284 release</li>
285 <li>Late validation fixes</li>
286 <li>Integrated a lot of contributed patches</li>
287 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]288 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]289</ul>
290
291<h3>2.2.4: Oct 1 2000:</h3>
292<ul>
293 <li>main XPath problem fixed</li>
294 <li>Integrated portability patches for Windows</li>
295 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]296</ul>
297
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]298<h3>2.2.3: Sep 17 2000</h3>
299<ul>
300 <li>bug fixes</li>
301 <li>cleanup of entity handling code</li>
302 <li>overall review of all loops in the parsers, all sprintf usage has been
303 checked too</li>
304 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
305 works smoothly now.</li>
306</ul>
307
308<h3>1.8.10: Sep 6 2000</h3>
309<ul>
310 <li>bug fix release for some Gnome projects</li>
311</ul>
312
313<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]314<ul>
315 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]316 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]317</ul>
318
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]319<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]320<ul>
321 <li>a purely bug fixes release</li>
322 <li>fixed an encoding support problem when parsing from a memory block</li>
323 <li>fixed a DOCTYPE parsing problem</li>
324 <li>removed a bug in the function allowing to override the memory allocation
325 routines</li>
326</ul>
327
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]328<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]329<ul>
330 <li>applied a lot of portability fixes</li>
331 <li>better encoding support/cleanup and saving (content is now always
332 encoded in UTF-8)</li>
333 <li>the HTML parser now correctly handles encodings</li>
334 <li>added xmlHasProp()</li>
335 <li>fixed a serious problem with &amp;#38;</li>
336 <li>propagated the fix to FTP client</li>
337 <li>cleanup, bugfixes, etc ...</li>
338 <li>Added a page about <a href="encoding.html">libxml Internationalization
339 support</a></li>
340</ul>
341
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]342<h3>1.8.9: July 9 2000</h3>
343<ul>
344 <li>fixed the spec the RPMs should be better</li>
345 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
346 rpmfind users problem</li>
347</ul>
348
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]349<h3>2.1.1: July 1 2000</h3>
350<ul>
351 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
352 <li>improvements on the HTML parser</li>
353</ul>
354
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]355<h3>2.1.0 and 1.8.8: June 29 2000</h3>
356<ul>
357 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
358 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
359 about &amp;#38; charref parsing</li>
360 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
361 also contains numerous fixes and enhancements:
362 <ul>
363 <li>added xmlStopParser() to stop parsing</li>
364 <li>improved a lot parsing speed when there is large CDATA blocs</li>
365 <li>includes XPath patches provided by Picdar Technology</li>
366 <li>tried to fix as much as possible DtD validation and namespace
367 related problems</li>
368 <li>output to a given encoding has been added/tested</li>
369 <li>lot of various fixes</li>
370 </ul>
371 </li>
372</ul>
373
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]374<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]375<ul>
376 <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]377 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
378 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
379 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]380 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]381 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]382 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]383 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]384 <pre>#include "xxx.h"</pre>
385 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]386 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
387 <li>the memory allocation routines used by libxml can now be overloaded
388 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]389 <li>The previously CVS only tool tester has been renamed
390 <strong>xmllint</strong> and is now installed as part of the libxml2
391 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]392 <li>The I/O interface has been revamped. There is now ways to plug in
393 specific I/O modules, either at the URI scheme detection level using
394 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
395 parser context using xmlCreateIOParserCtxt()</li>
396 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
397 number of the libxml module in use</li>
398 <li>a number of optional features of libxml can now be excluded at configure
399 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]400</ul>
401
402<h3>2.0.0beta: Mar 14 2000</h3>
403<ul>
404 <li>This is a first Beta release of libxml version 2</li>
405 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
406 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
407 tar and RPMs</li>
408 <li>This version is now the head in the Gnome CVS base, the old one is
409 available under the tag LIB_XML_1_X</li>
410 <li>This includes a very large set of changes. Froma programmatic point of
411 view applications should not have to be modified too much, check the <a
412 href="upgrade.html">upgrade page</a></li>
413 <li>Some interfaces may changes (especially a bit about encoding).</li>
414 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]415 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]416 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
417 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]418 <li>Better handling of entities, especially well formedness checking and
419 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]420 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]421 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]422 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
423 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]424 </ul>
425 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]426 <li>Serious progress were made toward compliance, <a
427 href="conf/result.html">here are the result of the test</a> against the
428 OASIS testsuite (except the japanese tests since I don't support that
429 encoding yet). This URL is rebuilt every couple of hours using the CVS
430 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]431</ul>
432
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]433<h3>1.8.7: Mar 6 2000</h3>
434<ul>
435 <li>This is a bug fix release:</li>
436 <li>It is possible to disable the ignorable blanks heuristic used by
437 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
438 that for adherence to XML spec, this behaviour will be disabled by default
439 in 2.x . The same function will allow to keep compatibility for old
440 code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]441 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
442 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]443 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
444 compilation on some platforms has been fixed</li>
445 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
446 URIs</li>
447</ul>
448
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]449<h3>1.8.6: Jan 31 2000</h3>
450<ul>
451 <li>added a nanoFTP transport module, debugged until the new version of <a
452 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
453 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]454</ul>
455
456<h3>1.8.5: Jan 21 2000</h3>
457<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]458 <li>adding APIs to parse a well balanced chunk of XML (production <a
459 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
460 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]461 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]462 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
463 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]464 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
465 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]466</ul>
467
468<h3>1.8.4: Jan 13 2000</h3>
469<ul>
470 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
471 <li>all exit() call should have been removed from libxml</li>
472 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
473 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]474</ul>
475
476<h3>1.8.3: Jan 5 2000</h3>
477<ul>
478 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]479 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]480 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]481 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]482 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
483 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]484 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]485 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]486 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]487</ul>
488
489<h3>1.8.2: Dec 21 1999</h3>
490<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]491 <li>I got another problem with includes and C++, I hope this issue is fixed
492 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]493 <li>Added a few tree modification functions: xmlReplaceNode,
494 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
495 xmlDocSetRootElement</li>
496 <li>Tried to improve the HTML output with help from <a
497 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]498</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]499
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]500<h3>1.8.1: Dec 18 1999</h3>
501<ul>
502 <li>various patches to avoid troubles when using libxml with C++ compilers
503 the "namespace" keyword and C escaping in include files</li>
504 <li>a problem in one of the core macros IS_CHAR was corrected</li>
505 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
506 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]507 <li>fixed a posteriori validation (validation after parsing, or by using a
508 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]509 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]510</ul>
511
512<h3>1.8.0: Dec 12 1999</h3>
513<ul>
514 <li>cleanup, especially memory wise</li>
515 <li>the parser should be more reliable, especially the HTML one, it should
516 not crash, whatever the input !</li>
517 <li>Integrated various patches, especially a speedup improvement for large
518 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
519 configure with --with-buffers to enable them.</li>
520 <li>attribute normalization, oops should have been added long ago !</li>
521 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
522 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]523</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]524
525<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]526<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]527 <li>Lots of HTML improvement</li>
528 <li>Fixed some errors when saving both XML and HTML</li>
529 <li>More examples, the regression tests should now look clean</li>
530 <li>Fixed a bug with contiguous charref</li>
531</ul>
532
533<h3>1.7.3: Sep 29 1999</h3>
534<ul>
535 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]536 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]537 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]538</ul>
539
540<h3>1.7.1: Sep 24 1999</h3>
541<ul>
542 <li>The basic type for strings manipulated by libxml has been renamed in
543 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
544 is that CHAR was conflicting with a predefined type on Windows. However on
545 non WIN32 environment, compatibility is provided by the way of a
546 <strong>#define </strong>.</li>
547 <li>Changed another error : the use of a structure field called errno, and
548 leading to troubles on platforms where it's a macro</li>
549</ul>
550
551<h3>1.7.0: sep 23 1999</h3>
552<ul>
553 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]554 href="html/gnome-xml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]555 <li>Added an errno to report errors by another mean than a simple printf
556 like callback</li>
557 <li>Finished ID/IDREF support and checking when validation</li>
558 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]559 href="html/gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]560 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
561 implementation</li>
562 <li>Added an HTML parser front-end</li>
563</ul>
564
565<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]566
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]567<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]568markup-based structured documents. Here is <a name="example">an example XML
569document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]570<pre>&lt;?xml version="1.0"?&gt;
571&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
572 &lt;head&gt;
573 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
574 &lt;/head&gt;
575 &lt;chapter&gt;
576 &lt;title&gt;The Linux adventure&lt;/title&gt;
577 &lt;p&gt;bla bla bla ...&lt;/p&gt;
578 &lt;image href="linus.gif"/&gt;
579 &lt;p&gt;...&lt;/p&gt;
580 &lt;/chapter&gt;
581&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]582
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]583<p>The first line specifies that it's an XML document and gives useful
584information about its encoding. Then the document is a text format whose
585structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]586to be closed</strong>. XML is pedantic about this. However, if a tag is empty
587(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]588ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note that,
589for example, the image tag has no content (just an attribute) and is closed by
590ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]591
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]592<p>XML can be applied sucessfully to a wide range of uses, from long term
593structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]594data encoding mechanisms like configuration file formatting (glade),
595spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
596it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]597
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]598<h2>An overview of libxml architecture</h2>
599
600<p>Libxml is made of multiple components, some of them optionals, and most of
601the block interfaces are public. The main components are:</p>
602<ul>
603 <li>an Input/Output layer</li>
604 <li>FTP and HTTP client layers (optionnal)</li>
605 <li>an Internationalization layer managing the encodings support</li>
606 <li>an URI module</li>
607 <li>the XML parser and its basic SAX interface</li>
608 <li>an HTML parser using the same SAX interface (optionnal)</li>
609 <li>a SAX tree module to build an in-memory DOM representation</li>
610 <li>a tree module to manipulate the DOM representation</li>
611 <li>a validation module using the DOM representation (optionnal)</li>
612 <li>an XPath module for global lookup in a DOM representation
613 (optionnal)</li>
614 <li>a debug module (optionnal)</li>
615</ul>
616
617<p>Graphically this gives the following:</p>
618
619<p><img src="libxml.gif" alt="a graphical view of the various"></p>
620
621<p></p>
622
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]623<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]624
625<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]626returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]627<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]628as the file name, the document type, and a <strong>children</strong> pointer
629which is the root of the document (or more exactly the first child under the
630root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]631chained in double-linked lists of siblings and with children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]632relationship. An xmlNode can also carry properties (a chain of xmlAttr
633structures). An attribute may have a value which is a list of TEXT or
634ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]635
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]636<p>Here is an example (erroneous with respect to the XML spec since there
637should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]638
639<p><img src="structure.gif" alt=" structure.gif "></p>
640
641<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]642called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]643prints them back as parsed. This is useful for detecting errors both in XML
644code and in the XML parser itself. It has an option <strong>--debug</strong>
645which prints the actual in-memory structure of the document, here is the
646result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]647<pre>DOCUMENT
648version=1.0
649standalone=true
650 ELEMENT EXAMPLE
651 ATTRIBUTE prop1
652 TEXT
653 content=gnome is great
654 ATTRIBUTE prop2
655 ENTITY_REF
656 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]657 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]658 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]659 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]660 TEXT
661 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]662 ELEMENT chapter
663 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]664 TEXT
665 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]666 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]667 TEXT
668 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]669 ELEMENT image
670 ATTRIBUTE href
671 TEXT
672 content=linus.gif
673 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]674 TEXT
675 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]676
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]677<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]678
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]679<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]680
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]681<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]682memory. In that case (and if you don't expect to save back the XML document
683loaded 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]684<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]685application layer registers a customized set of callbacks which are called by
686the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]687
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]688<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]689libxml, see the <a
690href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
691documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]692Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]693
694<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
695program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]696binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]697distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]698testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]699<pre>SAX.setDocumentLocator()
700SAX.startDocument()
701SAX.getEntity(amp)
702SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
703SAX.characters( , 3)
704SAX.startElement(head)
705SAX.characters( , 4)
706SAX.startElement(title)
707SAX.characters(Welcome to Gnome, 16)
708SAX.endElement(title)
709SAX.characters( , 3)
710SAX.endElement(head)
711SAX.characters( , 3)
712SAX.startElement(chapter)
713SAX.characters( , 4)
714SAX.startElement(title)
715SAX.characters(The Linux adventure, 19)
716SAX.endElement(title)
717SAX.characters( , 4)
718SAX.startElement(p)
719SAX.characters(bla bla bla ..., 15)
720SAX.endElement(p)
721SAX.characters( , 4)
722SAX.startElement(image, href='linus.gif')
723SAX.endElement(image)
724SAX.characters( , 4)
725SAX.startElement(p)
726SAX.characters(..., 3)
727SAX.endElement(p)
728SAX.characters( , 3)
729SAX.endElement(chapter)
730SAX.characters( , 1)
731SAX.endElement(EXAMPLE)
732SAX.endDocument()</pre>
733
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]734<p>Most of the other functionalities of libxml are based on the DOM
735tree-building facility, so nearly everything up to the end of this document
736presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]737itself is built by a set of registered default callbacks, without internal
738specific interface.</p>
739
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]740<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]741
742<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]743using the XML library from the C language. It is not intended to be extensive.
744I hope the automatically generated documents will provide the completeness
745required, but as a separate set of documents. The interfaces of the XML
746library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]747interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]748
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]749<p>The <a href="html/gnome-xml-parser.html">parser interfaces for XML</a> are
750separated from the <a href="html/gnome-xml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]751interfaces</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]752
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]753<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]754
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]755<p>Usually, the first thing to do is to read an XML input. The parser accepts
756documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]757defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]758<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]759 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]760 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]761 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]762</dl>
763<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]764 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]765 <dd><p>Parse an XML document contained in a (possibly compressed)
766 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]767 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]768</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]769
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]770<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]771failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]772
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]773<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]774
775<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]776fetched (which is common for GUI based programs) libxml provides a push
777interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]778<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
779 void *user_data,
780 const char *chunk,
781 int size,
782 const char *filename);
783int xmlParseChunk (xmlParserCtxtPtr ctxt,
784 const char *chunk,
785 int size,
786 int terminate);</pre>
787
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]788<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]789<pre> FILE *f;
790
791 f = fopen(filename, "r");
792 if (f != NULL) {
793 int res, size = 1024;
794 char chars[1024];
795 xmlParserCtxtPtr ctxt;
796
797 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]798 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]799 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
800 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]801 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]802 xmlParseChunk(ctxt, chars, res, 0);
803 }
804 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]805 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]806 xmlFreeParserCtxt(ctxt);
807 }
808 }</pre>
809
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]810<p>Also note that the HTML parser embedded into libxml also has a push
811interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]812
813<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
814
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]815<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]816memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]817Reading a document without building the tree is possible using the SAX
818interfaces (see SAX.h and <a
819href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]820Henstridge's documentation</a>). Note also that the push interface can be
821limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]822<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]823
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]824<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]825
826<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]827there is a set of functions dedicated to building new elements. (These are
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]828also 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]829that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]830<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]831 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]832 xmlNodePtr tree, subtree;
833
834 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]835 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
836 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
837 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
838 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]839 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]840 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]841 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
842 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
843 subtree = xmlNewChild(tree, NULL, "image", NULL);
844 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]845
846<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]847
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]848<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]849
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]850<p>Basically by <a href="html/gnome-xml-tree.html">including "tree.h"</a> your
851code has access to the internal structure of all the elements of the tree. The
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]852names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]853<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]854<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]855example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]856<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]857
858<p>points to the title element,</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]859<pre>doc-&gt;children-&gt;children-&gt;next-&gt;child-&gt;child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]860
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]861<p>points to the text node containing the chapter title "The Linux
862adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]863
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]864<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]865present before the document root, so <code>doc-&gt;children</code> may point
866to an element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]867<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]868
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]869<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]870
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]871<p>Functions are provided for reading and writing the document content. Here
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]872is 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]873<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]874 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
875 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]876 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
877 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]878 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]879</dl>
880<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]881 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]882 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]883 <dd><p>This function returns a pointer to new copy of the property
884 content. Note that the user must deallocate the result.</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>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]887
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]888<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]889elements:</p>
890<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]891 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]892 *value);</code></dt>
893 <dd><p>This function takes an "external" string and convert it to one text
894 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]895 entity references like &amp;Gnome; will be stored internally as entity
896 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]897 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]898</dl>
899<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]900 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]901 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]902 <dd><p>This function is the inverse of
903 <code>xmlStringGetNodeList()</code>. It generates a new string
904 containing the content of the text and entity nodes. Note the extra
905 argument inLine. If this argument is set to 1, the function will expand
906 entity references. For example, instead of returning the &amp;Gnome;
907 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]908 "GNU Network Object Model Environment"). Set this argument if you want
909 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]910 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]911</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]912
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]913<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]914
915<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]916<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]917 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]918 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]919 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]920 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]921</dl>
922<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]923 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]924 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]925 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]926</dl>
927<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]928 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]929 <dd><p>Saves the document to a file. In this case, the compression
930 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]931 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]932</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]933
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]934<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]935
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]936<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]937accesses. The level of compression on saves can be turned on either globally
938or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]939<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]940 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]941 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]942 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]943</dl>
944<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]945 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]946 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]947 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]948</dl>
949<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]950 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]951 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]952 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]953</dl>
954<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]955 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]956 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]957 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]958</dl>
959
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]960<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]961
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]962<p>Entities in principle are similar to simple C macros. An entity defines an
963abbreviation for a given string that you can reuse many times throughout the
964content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]965may occur frequently within a document, or to confine the change needed to a
966document to a restricted area in the internal subset of the document (at the
967beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]968<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9692 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9703 &lt;!ENTITY xml "Extensible Markup Language"&gt;
9714 ]&gt;
9725 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]9736 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]9747 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]975
976<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]977it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]978are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]979predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]980<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]981for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]982<strong>&amp;quot;</strong> for the character '"', and
983<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]984
985<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]986substitute an entity's content so that you can see the replacement text in
987your application. Or you may prefer to keep entity references as such in the
988content to be able to save the document back without losing this usually
989precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]990entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]991them as saving time). The <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]992href="html/gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]993function allows you to check and change the behaviour, which is to not
994substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]995
996<p>Here is the DOM tree built by libxml for the previous document in the
997default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]998<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]999DOCUMENT
1000version=1.0
1001 ELEMENT EXAMPLE
1002 TEXT
1003 content=
1004 ENTITY_REF
1005 INTERNAL_GENERAL_ENTITY xml
1006 content=Extensible Markup Language
1007 TEXT
1008 content=</pre>
1009
1010<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1011<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1012DOCUMENT
1013version=1.0
1014 ELEMENT EXAMPLE
1015 TEXT
1016 content= Extensible Markup Language</pre>
1017
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1018<p>So, entities or no entities? Basically, it depends on your use case. I
1019suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1020entities in your XML document or data if you are not willing to handle the
1021entity references elements in the DOM tree.</p>
1022
1023<p>Note that at save time libxml enforce the conversion of the predefined
1024entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1025transparently replace those with chars (i.e., it will not generate entity
1026reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1027finding them in the input).</p>
1028
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1029<p><span style="background-color: #FF0000">WARNING</span>: handling entities
1030on top of libxml SAX interface is difficult !!! If you plan to use
1031non-predefined entities in your documents, then the learning cuvre to handle
1032then using the SAX API may be long. If you plan to use complex document, I
1033strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]1034deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]1035
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1036<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1037
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1038<p>The libxml library implements <a
1039href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
1040recognizing namespace contructs in the input, and does namespace lookup
1041automatically when building the DOM tree. A namespace declaration is
1042associated with an in-memory structure and all elements or attributes within
1043that namespace point to it. Hence testing the namespace is a simple and fast
1044equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1045
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1046<p>I suggest that people using libxml use a namespace, and declare it in the
1047root element of their document as the default namespace. Then they don't need
1048to use the prefix in the content but we will have a basis for future semantic
1049refinement and merging of data from different sources. This doesn't augment
1050significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1051in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1052<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
1053 &lt;elem1&gt;...&lt;/elem1&gt;
1054 &lt;elem2&gt;...&lt;/elem2&gt;
1055&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1056
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1057<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]1058have to point to any existing resource on the Web. It will bind all the
1059element and atributes with that URL. I suggest to use an URL within a domain
1060you control, and that the URL should contain some kind of version information
1061if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1062a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1063
1064<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1065version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1066and if the version information don't match something you know, warn the user
1067and 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]1068namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
1069same as &lt;bar:text&gt; in another document. What really matter is the URI
1070associated with the element or the attribute, not the prefix string (which is
1071just a shortcut for the full URI). In libxml element and attributes have a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]1072<code>ns</code> field pointing to an xmlNs structure detailing the namespace
1073prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1074
1075<p>@@Interfaces@@</p>
1076
1077<p>@@Examples@@</p>
1078
1079<p>Usually people object using namespace in the case of validation, I object
1080this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1081so even is you plan to use or currently are using validation I strongly
1082suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1083<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1084flexible parsers. Now using namespace to mix and differentiate content coming
1085from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1086to provide ways to do this, but this may not be portable or standardized.</p>
1087
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1088<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1089
1090<p>Well what is validation and what is a DTD ?</p>
1091
1092<p>Validation is the process of checking a document against a set of
1093construction rules, a <strong>DTD</strong> (Document Type Definition) is such
1094a set of rules.</p>
1095
1096<p>The validation process and building DTDs are the two most difficult parts
1097of XML life cycle. Briefly a DTD defines all the possibles element to be
1098found within your document, what is the formal shape of your document tree (by
1099defining the allowed content of an element, either text, a regular expression
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1100for the allowed list of children, or mixed content i.e. both text and
1101children). The DTD also defines the allowed attributes for all elements and
1102the types of the attributes. For more detailed informations, I suggest to read
1103the related parts of the XML specification, the examples found under
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1104gnome-xml/test/valid/dtd and the large amount of books available on XML. The
1105dia example in gnome-xml/test/valid should be both simple and complete enough
1106to allow you to build your own.</p>
1107
1108<p>A word of warning, building a good DTD which will fit your needs of your
1109application in the long-term is far from trivial, however the extra level of
1110quality it can insure is well worth the price for some sets of applications or
1111if you already have already a DTD defined for your application field.</p>
1112
1113<p>The validation is not completely finished but in a (very IMHO) usable
1114state. Until a real validation interface is defined the way to do it is to
1115define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
1116variable to 1, this will of course be changed at some point:</p>
1117
1118<p>extern int xmlDoValidityCheckingDefaultValue;</p>
1119
1120<p>...</p>
1121
1122<p>xmlDoValidityCheckingDefaultValue = 1;</p>
1123
1124<p></p>
1125
1126<p>To handle external entities, use the function
1127<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
1128link in you HTTP/FTP/Entities database library to the standard libxml
1129core.</p>
1130
1131<p>@@interfaces@@</p>
1132
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1133<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1134
1135<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]1136Model</em> this is an API for accessing XML or HTML structured documents.
1137Native 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]1138be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]1139files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1140set of IDL (or Java) interfaces allowing to traverse and manipulate a
1141document. The DOM library will allow accessing and modifying "live" documents
1142presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1143
1144<p><img src="DOM.gif" alt=" DOM.gif "></p>
1145
1146<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1147embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1148
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1149<p>The current DOM implementation on top of libxml is the <a
1150href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
1151a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
1152Levien</a>.</p>
1153
1154<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
1155
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1156<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1157
1158<p>Here is a real size example, where the actual content of the application
1159data 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]1160a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1161storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
1162base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1163<pre>&lt;?xml version="1.0"?&gt;
1164&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
1165 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1166
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1167 &lt;gjob:Job&gt;
1168 &lt;gjob:Project ID="3"/&gt;
1169 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
1170 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1171
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1172 &lt;gjob:Update&gt;
1173 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
1174 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
1175 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
1176 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1177
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1178 &lt;gjob:Developers&gt;
1179 &lt;gjob:Developer&gt;
1180 &lt;/gjob:Developer&gt;
1181 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1182
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1183 &lt;gjob:Contact&gt;
1184 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
1185 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
1186 &lt;gjob:Company&gt;
1187 &lt;/gjob:Company&gt;
1188 &lt;gjob:Organisation&gt;
1189 &lt;/gjob:Organisation&gt;
1190 &lt;gjob:Webpage&gt;
1191 &lt;/gjob:Webpage&gt;
1192 &lt;gjob:Snailmail&gt;
1193 &lt;/gjob:Snailmail&gt;
1194 &lt;gjob:Phone&gt;
1195 &lt;/gjob:Phone&gt;
1196 &lt;/gjob:Contact&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:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1199 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1200 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1201
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1202 &lt;gjob:Skills&gt;
1203 &lt;/gjob:Skills&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:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1206 A GNOME based system that will allow a superuser to configure
1207 compressed and uncompressed files and/or file systems to be backed
1208 up with a supported media in the system. This should be able to
1209 perform via find commands generating a list of files that are passed
1210 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1211 or via operations performed on the filesystem itself. Email
1212 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1213 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1214
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1215 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1216
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1217 &lt;/gjob:Jobs&gt;
1218&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1219
1220<p>While loading the XML file into an internal DOM tree is a matter of calling
1221only a couple of functions, browsing the tree to gather the informations and
1222generate the internals structures is harder, and more error prone.</p>
1223
1224<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1225structure. For example, the ordering of the attributes is not significant,
1226Cthe 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]1227be dependent of the orders of the children of a given node, unless it really
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1228makes things harder. Here is some code to parse the informations for a
1229person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1230<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1231 * A person record
1232 */
1233typedef struct person {
1234 char *name;
1235 char *email;
1236 char *company;
1237 char *organisation;
1238 char *smail;
1239 char *webPage;
1240 char *phone;
1241} person, *personPtr;
1242
1243/*
1244 * And the code needed to parse it
1245 */
1246personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1247 personPtr ret = NULL;
1248
1249DEBUG("parsePerson\n");
1250 /*
1251 * allocate the struct
1252 */
1253 ret = (personPtr) malloc(sizeof(person));
1254 if (ret == NULL) {
1255 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1256 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1257 }
1258 memset(ret, 0, sizeof(person));
1259
1260 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1261 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1262 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1263 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
1264 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1265 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
1266 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1267 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1268 }
1269
1270 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1271}</pre>
1272
1273<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1274<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1275 <li>Usually a recursive parsing style is the more convenient one, XML data
1276 being by nature subject to repetitive constructs and usualy exibit highly
1277 stuctured patterns.</li>
1278 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1279 the pointer to the global XML document and the namespace reserved to the
1280 application. Document wide information are needed for example to decode
1281 entities and it's a good coding practice to define a namespace for your
1282 application set of data and test that the element and attributes you're
1283 analyzing actually pertains to your application space. This is done by a
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1284 simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1285 <li>To retrieve text and attributes value, it is suggested to use the
1286 function <em>xmlNodeListGetString</em> to gather all the text and entity
1287 reference nodes generated by the DOM output and produce an single text
1288 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1289</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1290
1291<p>Here is another piece of code used to parse another level of the
1292structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1293<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1294/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1295 * a Description for a Job
1296 */
1297typedef struct job {
1298 char *projectID;
1299 char *application;
1300 char *category;
1301 personPtr contact;
1302 int nbDevelopers;
1303 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1304} job, *jobPtr;
1305
1306/*
1307 * And the code needed to parse it
1308 */
1309jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1310 jobPtr ret = NULL;
1311
1312DEBUG("parseJob\n");
1313 /*
1314 * allocate the struct
1315 */
1316 ret = (jobPtr) malloc(sizeof(job));
1317 if (ret == NULL) {
1318 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1319 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1320 }
1321 memset(ret, 0, sizeof(job));
1322
1323 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1324 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1325 while (cur != NULL) {
1326
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1327 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
1328 ret-&gt;projectID = xmlGetProp(cur, "ID");
1329 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1330 fprintf(stderr, "Project has no ID\n");
1331 }
1332 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1333 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
1334 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1335 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
1336 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
1337 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
1338 ret-&gt;contact = parsePerson(doc, ns, cur);
1339 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1340 }
1341
1342 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1343}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1344
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1345<p>One can notice that once used to it, writing this kind of code is quite
1346simple, but boring. Ultimately, it could be possble to write stubbers taking
1347either C data structure definitions, a set of XML examples or an XML DTD and
1348produce the code needed to import and export the content between C data and
1349XML storage. This is left as an exercise to the reader :-)</p>
1350
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]1351<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1352parsing example</a> as a template, it is also available with Makefile in the
1353Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1354
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1355<h2><a name="Contributi">Contributions</a></h2>
1356<ul>
Daniel Veillard851c59c2000-11-24 16:06:22 +0000[diff] [blame^]1357 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1358 for libxml:
1359 <p>Website: <a
1360 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1361 <p>Download: <a
1362 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1363 </li>
1364 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1365 precompiled Windows version
1366 <p><a
1367 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1368 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1369 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1370 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1371 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1372 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1373 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1374 integrated in the distribution)</li>
1375</ul>
1376
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1377<p></p>
1378
1379<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1380
Daniel Veillard851c59c2000-11-24 16:06:22 +0000[diff] [blame^]1381<p>$Id: xml.html,v 1.59 2000/11/24 13:04:03 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1382</body>
1383</html>