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blob: 966f8eb1c7978648ebdbbdee5dd5a26bef6f0d84 [file] [log] [blame]
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2 "http://www.w3.org/TR/REC-html40/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]5 <title>The XML library for Gnome</title>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V2.1">
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 Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]11<p><a href="http://www.gnome.org/"><img src="smallfootonly.gif" alt="Gnome
12Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C
13Logo"></a></p>
14
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]15<h1 align="center">The XML 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 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 Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]45 <li><a href="#Contributi">Contribution</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]46</ul>
47
48<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]49
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]50<p>This document describes libxml, the <a
51href="http://www.w3.org/XML/">XML</a> library provided in the <a
52href="http://www.gnome.org/">Gnome</a> framework. XML is a standard for
53building tag-based structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]54
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]55<p>Here are some key points about libxml:</p>
56<ul>
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame^]57 <li>It is written in plain C, making as few assumptions as possible and
58 sticking closely to ANSI C for easy embedding.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]59 <li>The internal document repesentation is as close as possible to the <a
60 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
61 <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]62 like interface</a>; the interface is designed to be compatible with <a
63 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]64 <li>Libxml now includes a nearly complete <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]65 href="http://www.w3.org/TR/xpath">XPath</a> implementation.</li>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]66 <li>Libxml exports Push and Pull type parser interfaces for both XML and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]67 HTML.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]68 <li>This library is released both under the <a
69 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
70 IPR</a> and the GNU LGPL. Use either at your convenience, basically this
71 should make everybody happy, if not, drop me a mail.</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]72 <li>There is <a href="upgrade.html">a first set of instructions</a>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]73 concerning upgrade from libxml-1.x to libxml-2.x</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]74</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]75
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]76<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]77
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]78<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]79<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]80 <li>Check the <a href="FAQ.html">FAQ</a></li>
81 <li>Check the <a href="http://xmlsoft.org/libxml.html">extensive
82 documentation</a> automatically extracted from code comments.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]83 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]84 examples</a> on how to use libxml.</li>
85 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
86 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
87 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]88 <li>George Lebl wrote <a
89 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]90 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]91 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
92 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
93 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]94 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]95 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
96 href="http://www.levien.com/svg/">gill</a>. Check his <a
97 href="http://www.levien.com/gnome/domination.html">DOMination
98 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]99 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
100 file</a></li>
101 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
102 starting a new project using libxml you should really use the 2.x
103 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]104 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]105 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]106</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]107
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108<h3>Reporting bugs and getting help</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]109
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]110<p>Well, bugs or missing features are always possible, and I will make a point
111of fixing them in a timely fashion. The best way to report a bug is to <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]112href="http://bugs.gnome.org/db/pa/lgnome-xml.html">use the Gnome bug tracking
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]113database</a>. I look at reports there regularly and it's good to have a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]114reminder when a bug is still open. Check the <a
115href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]116and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]117
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]118<p>There is also a mailing-list <a
119href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> for libxml, with an <a
120href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]121majordomo based list, send a mail message to <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]122href="mailto:majordomo@rufus.w3.org">majordomo@rufus.w3.org</a> with
123"subscribe xml" in the <strong>content</strong> of the message.</p>
124
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]125<p>Alternatively, you can just send the bug to the <a
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]126href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> list.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]127
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]128<p>Of course, bugs reports with a suggested patch for fixing them will
129probably be processed faster.</p>
130
131<p>If you're looking for help, a quick look at <a
132href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
133provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame^]134questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]135documentantion</a> is not as polished as I would like (i need to learn more
136about Docbook), but it's a good starting point.</p>
137
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]138<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]139
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]140<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]141href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]142href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]143as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]144archive</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/contrib/rpms/">RPM
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]145packages</a>. (NOTE that you need both the <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]146href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
147href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]148packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]149
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]150<p><a name="Snapshot">Snapshot:</a></p>
151<ul>
152 <li>Code from the W3C cvs base libxml <a
153 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
154 <li>Docs, content of the web site, the list archive included <a
155 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
156</ul>
157
158<p><a name="Contribs">Contribs:</a></p>
159
160<p>I do accept external contributions, especially if compiling on another
161platform, get in touch with me to upload the package. I will keep them in the
162<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
163
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]164<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]165<ul>
166 <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]167 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]168 this base for my own development, so it's updated more regularly, but the
169 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]170 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]171 password: anonymous
172 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]173 </li>
174 <li><p>The <a
175 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]176 CVS base</a>. Check the <a
177 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
178 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]179 </li>
180</ul>
181
182<h2><a name="News">News</a></h2>
183
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]184<h3>CVS only : check the <a
185href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
186for really accurate description</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]187<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]188 <li>working on HTML and XML links recognition layers, get in touch with me
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]189 if you want to test those.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]190</ul>
191
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]192<h3>2.1.0 and 1.8.8: June 29 2000</h3>
193<ul>
194 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
195 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
196 about &amp;#38; charref parsing</li>
197 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
198 also contains numerous fixes and enhancements:
199 <ul>
200 <li>added xmlStopParser() to stop parsing</li>
201 <li>improved a lot parsing speed when there is large CDATA blocs</li>
202 <li>includes XPath patches provided by Picdar Technology</li>
203 <li>tried to fix as much as possible DtD validation and namespace
204 related problems</li>
205 <li>output to a given encoding has been added/tested</li>
206 <li>lot of various fixes</li>
207 </ul>
208 </li>
209</ul>
210
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]211<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]212<ul>
213 <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]214 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
215 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
216 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]217 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]218 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]219 <pre>#include &lt;libxml/xxx.h></pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]220 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]221 <pre>#include "xxx.h"</pre>
222 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]223 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
224 <li>the memory allocation routines used by libxml can now be overloaded
225 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]226 <li>The previously CVS only tool tester has been renamed
227 <strong>xmllint</strong> and is now installed as part of the libxml2
228 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]229 <li>The I/O interface has been revamped. There is now ways to plug in
230 specific I/O modules, either at the URI scheme detection level using
231 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
232 parser context using xmlCreateIOParserCtxt()</li>
233 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
234 number of the libxml module in use</li>
235 <li>a number of optional features of libxml can now be excluded at configure
236 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]237</ul>
238
239<h3>2.0.0beta: Mar 14 2000</h3>
240<ul>
241 <li>This is a first Beta release of libxml version 2</li>
242 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
243 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
244 tar and RPMs</li>
245 <li>This version is now the head in the Gnome CVS base, the old one is
246 available under the tag LIB_XML_1_X</li>
247 <li>This includes a very large set of changes. Froma programmatic point of
248 view applications should not have to be modified too much, check the <a
249 href="upgrade.html">upgrade page</a></li>
250 <li>Some interfaces may changes (especially a bit about encoding).</li>
251 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]252 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]253 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
254 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]255 <li>Better handling of entities, especially well formedness checking and
256 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]257 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]258 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]259 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
260 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]261 </ul>
262 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]263 <li>Serious progress were made toward compliance, <a
264 href="conf/result.html">here are the result of the test</a> against the
265 OASIS testsuite (except the japanese tests since I don't support that
266 encoding yet). This URL is rebuilt every couple of hours using the CVS
267 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]268</ul>
269
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]270<h3>1.8.7: Mar 6 2000</h3>
271<ul>
272 <li>This is a bug fix release:</li>
273 <li>It is possible to disable the ignorable blanks heuristic used by
274 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
275 that for adherence to XML spec, this behaviour will be disabled by default
276 in 2.x . The same function will allow to keep compatibility for old
277 code.</li>
278 <li>Blanks in &lt;a> &lt;/a> constructs are not ignored anymore, avoiding
279 heuristic is really the Right Way :-\</li>
280 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
281 compilation on some platforms has been fixed</li>
282 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
283 URIs</li>
284</ul>
285
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]286<h3>1.8.6: Jan 31 2000</h3>
287<ul>
288 <li>added a nanoFTP transport module, debugged until the new version of <a
289 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
290 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]291</ul>
292
293<h3>1.8.5: Jan 21 2000</h3>
294<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]295 <li>adding APIs to parse a well balanced chunk of XML (production <a
296 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
297 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]298 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
299 <li>Jody Goldberg &lt;jgoldberg@home.com> provided another patch trying to
300 solve the zlib checks problems</li>
301 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
302 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]303</ul>
304
305<h3>1.8.4: Jan 13 2000</h3>
306<ul>
307 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
308 <li>all exit() call should have been removed from libxml</li>
309 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
310 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]311</ul>
312
313<h3>1.8.3: Jan 5 2000</h3>
314<ul>
315 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]316 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]317 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]318 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]319 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
320 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]321 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]322 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]323 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]324</ul>
325
326<h3>1.8.2: Dec 21 1999</h3>
327<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]328 <li>I got another problem with includes and C++, I hope this issue is fixed
329 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]330 <li>Added a few tree modification functions: xmlReplaceNode,
331 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
332 xmlDocSetRootElement</li>
333 <li>Tried to improve the HTML output with help from <a
334 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]335</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]336
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]337<h3>1.8.1: Dec 18 1999</h3>
338<ul>
339 <li>various patches to avoid troubles when using libxml with C++ compilers
340 the "namespace" keyword and C escaping in include files</li>
341 <li>a problem in one of the core macros IS_CHAR was corrected</li>
342 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
343 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]344 <li>fixed a posteriori validation (validation after parsing, or by using a
345 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]346 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]347</ul>
348
349<h3>1.8.0: Dec 12 1999</h3>
350<ul>
351 <li>cleanup, especially memory wise</li>
352 <li>the parser should be more reliable, especially the HTML one, it should
353 not crash, whatever the input !</li>
354 <li>Integrated various patches, especially a speedup improvement for large
355 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
356 configure with --with-buffers to enable them.</li>
357 <li>attribute normalization, oops should have been added long ago !</li>
358 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
359 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]360</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]361
362<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]363<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]364 <li>Lots of HTML improvement</li>
365 <li>Fixed some errors when saving both XML and HTML</li>
366 <li>More examples, the regression tests should now look clean</li>
367 <li>Fixed a bug with contiguous charref</li>
368</ul>
369
370<h3>1.7.3: Sep 29 1999</h3>
371<ul>
372 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]373 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]374 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]375</ul>
376
377<h3>1.7.1: Sep 24 1999</h3>
378<ul>
379 <li>The basic type for strings manipulated by libxml has been renamed in
380 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
381 is that CHAR was conflicting with a predefined type on Windows. However on
382 non WIN32 environment, compatibility is provided by the way of a
383 <strong>#define </strong>.</li>
384 <li>Changed another error : the use of a structure field called errno, and
385 leading to troubles on platforms where it's a macro</li>
386</ul>
387
388<h3>1.7.0: sep 23 1999</h3>
389<ul>
390 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
391 href="gnome-xml-nanohttp.html">nanohttp</a> module.</li>
392 <li>Added an errno to report errors by another mean than a simple printf
393 like callback</li>
394 <li>Finished ID/IDREF support and checking when validation</li>
395 <li>Serious memory leaks fixed (there is now a <a
396 href="gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
397 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
398 implementation</li>
399 <li>Added an HTML parser front-end</li>
400</ul>
401
402<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]403
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]404<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]405markup-based structured documents. Here is <a name="example">an example XML
406document</a>:</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]407<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]408&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]409 &lt;head>
410 &lt;title>Welcome to Gnome&lt;/title>
411 &lt;/head>
412 &lt;chapter>
413 &lt;title>The Linux adventure&lt;/title>
414 &lt;p>bla bla bla ...&lt;/p>
415 &lt;image href="linus.gif"/>
416 &lt;p>...&lt;/p>
417 &lt;/chapter>
418&lt;/EXAMPLE></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]419
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]420<p>The first line specifies that it's an XML document and gives useful
421information about its encoding. Then the document is a text format whose
422structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]423to be closed</strong>. XML is pedantic about this. However, if a tag is empty
424(no content), a single tag can serve as both the opening and closing tag if it
425ends with <code>/></code> rather than with <code>></code>. Note that, for
426example, the image tag has no content (just an attribute) and is closed by
427ending the tag with <code>/></code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]428
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]429<p>XML can be applied sucessfully to a wide range of uses, from long term
430structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]431data encoding mechanisms like configuration file formatting (glade),
432spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
433it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]434
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]435<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]436
437<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]438returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]439<strong>xmlDoc</strong> structure). This structure contains information such
440as the file name, the document type, and a <strong>root</strong> pointer which
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]441is the root of the document (or more exactly the first child under the root
442which is the document). The tree is made of <strong>xmlNode</strong>s, chained
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]443in double-linked lists of siblings and with childs&lt;->parent relationship.
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]444An xmlNode can also carry properties (a chain of xmlAttr structures). An
445attribute may have a value which is a list of TEXT or ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]446
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]447<p>Here is an example (erroneous with respect to the XML spec since there
448should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]449
450<p><img src="structure.gif" alt=" structure.gif "></p>
451
452<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]453called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]454prints them back as parsed. This is useful for detecting errors both in XML
455code and in the XML parser itself. It has an option <strong>--debug</strong>
456which prints the actual in-memory structure of the document, here is the
457result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]458<pre>DOCUMENT
459version=1.0
460standalone=true
461 ELEMENT EXAMPLE
462 ATTRIBUTE prop1
463 TEXT
464 content=gnome is great
465 ATTRIBUTE prop2
466 ENTITY_REF
467 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]468 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]469 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]470 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]471 TEXT
472 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]473 ELEMENT chapter
474 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]475 TEXT
476 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]477 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]478 TEXT
479 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]480 ELEMENT image
481 ATTRIBUTE href
482 TEXT
483 content=linus.gif
484 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]485 TEXT
486 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]487
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]488<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]489
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]490<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]491
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]492<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]493memory. In that case (and if you don't expect to save back the XML document
494loaded 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]495<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]496application layer registers a customized set of callbacks which are called by
497the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]498
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]499<p>To get more detailed step-by-step guidance on using the SAX interface of
500libxml, see the
501href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]502documentation.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]503Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]504
505<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
506program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]507binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]508distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]509testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]510<pre>SAX.setDocumentLocator()
511SAX.startDocument()
512SAX.getEntity(amp)
513SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
514SAX.characters( , 3)
515SAX.startElement(head)
516SAX.characters( , 4)
517SAX.startElement(title)
518SAX.characters(Welcome to Gnome, 16)
519SAX.endElement(title)
520SAX.characters( , 3)
521SAX.endElement(head)
522SAX.characters( , 3)
523SAX.startElement(chapter)
524SAX.characters( , 4)
525SAX.startElement(title)
526SAX.characters(The Linux adventure, 19)
527SAX.endElement(title)
528SAX.characters( , 4)
529SAX.startElement(p)
530SAX.characters(bla bla bla ..., 15)
531SAX.endElement(p)
532SAX.characters( , 4)
533SAX.startElement(image, href='linus.gif')
534SAX.endElement(image)
535SAX.characters( , 4)
536SAX.startElement(p)
537SAX.characters(..., 3)
538SAX.endElement(p)
539SAX.characters( , 3)
540SAX.endElement(chapter)
541SAX.characters( , 1)
542SAX.endElement(EXAMPLE)
543SAX.endDocument()</pre>
544
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]545<p>Most of the other functionalities of libxml are based on the DOM
546tree-building facility, so nearly everything up to the end of this document
547presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]548itself is built by a set of registered default callbacks, without internal
549specific interface.</p>
550
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]551<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]552
553<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]554using the XML library from the C language. It is not intended to be extensive.
555I hope the automatically generated documents will provide the completeness
556required, but as a separate set of documents. The interfaces of the XML
557library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]558interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]559
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]560<p>The <a href="gnome-xml-parser.html">parser interfaces for XML</a> are
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]561separated from the <a href="gnome-xml-htmlparser.html">HTML parser
562interfaces</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]563
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]564<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]565
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]566<p>Usually, the first thing to do is to read an XML input. The parser accepts
567documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]568defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]569<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]570 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]571 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]572 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]573</dl>
574<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]575 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]576 <dd><p>Parse an XML document contained in a (possibly compressed)
577 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]578 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]579</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]580
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]581<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]582failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]583
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]584<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]585
586<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]587fetched (which is common for GUI based programs) libxml provides a push
588interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]589<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
590 void *user_data,
591 const char *chunk,
592 int size,
593 const char *filename);
594int xmlParseChunk (xmlParserCtxtPtr ctxt,
595 const char *chunk,
596 int size,
597 int terminate);</pre>
598
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]599<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]600<pre> FILE *f;
601
602 f = fopen(filename, "r");
603 if (f != NULL) {
604 int res, size = 1024;
605 char chars[1024];
606 xmlParserCtxtPtr ctxt;
607
608 res = fread(chars, 1, 4, f);
609 if (res > 0) {
610 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
611 chars, res, filename);
612 while ((res = fread(chars, 1, size, f)) > 0) {
613 xmlParseChunk(ctxt, chars, res, 0);
614 }
615 xmlParseChunk(ctxt, chars, 0, 1);
616 doc = ctxt->myDoc;
617 xmlFreeParserCtxt(ctxt);
618 }
619 }</pre>
620
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]621<p>Also note that the HTML parser embedded into libxml also has a push
622interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]623
624<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
625
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]626<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]627memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]628Reading a document without building the tree is possible using the SAX
629interfaces (see SAX.h and <a
630href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]631Henstridge's documentation</a>). Note also that the push interface can be
632limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]633<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]634
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]635<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]636
637<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]638there is a set of functions dedicated to building new elements. (These are
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]639also described in &lt;libxml/tree.h>.) For example, here is a piece of code
640that produces the XML document used in the previous examples:</p>
641<pre> #include &lt;libxml/tree.h>
642 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]643 xmlNodePtr tree, subtree;
644
645 doc = xmlNewDoc("1.0");
646 doc->root = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
647 xmlSetProp(doc->root, "prop1", "gnome is great");
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]648 xmlSetProp(doc->root, "prop2", "&amp; linux too");
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]649 tree = xmlNewChild(doc->root, NULL, "head", NULL);
650 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
651 tree = xmlNewChild(doc->root, NULL, "chapter", NULL);
652 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
653 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
654 subtree = xmlNewChild(tree, NULL, "image", NULL);
655 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]656
657<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]658
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]659<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]660
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]661<p>Basically by <a href="gnome-xml-tree.html">including "tree.h"</a> your code
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]662has access to the internal structure of all the elements of the tree. The
663names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]664<strong>childs</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]665<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]666example:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]667<pre><code>doc->root->childs->childs</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]668
669<p>points to the title element,</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]670<pre>doc->root->childs->next->child->child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]671
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]672<p>points to the text node containing the chapter title "The Linux
673adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]674
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]675<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]676present before the document root, so <code>doc->root</code> may point to an
677element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]678<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]679
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]680<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]681
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]682<p>Functions are provided for reading and writing the document content. Here
683is an excerpt from the <a href="gnome-xml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]684<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]685 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
686 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]687 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
688 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]689 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]690</dl>
691<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]692 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]693 *name);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]694 <dd><p>This function returns a pointer to the property content. Note that
695 no extra copy is made.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]696 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]697</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]698
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]699<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]700elements:</p>
701<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]702 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]703 *value);</code></dt>
704 <dd><p>This function takes an "external" string and convert it to one text
705 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]706 entity references like &amp;Gnome; will be stored internally as entity
707 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]708 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]709</dl>
710<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]711 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]712 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]713 <dd><p>This function is the inverse of
714 <code>xmlStringGetNodeList()</code>. It generates a new string
715 containing the content of the text and entity nodes. Note the extra
716 argument inLine. If this argument is set to 1, the function will expand
717 entity references. For example, instead of returning the &amp;Gnome;
718 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]719 "GNU Network Object Model Environment"). Set this argument if you want
720 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]721 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]722</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]723
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]724<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]725
726<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]727<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]728 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]729 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]730 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]731 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]732</dl>
733<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]734 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]735 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]736 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]737</dl>
738<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]739 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]740 <dd><p>Saves the document to a file. In this case, the compression
741 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]742 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]743</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]744
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]745<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]746
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]747<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]748accesses. The level of compression on saves can be turned on either globally
749or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]750<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]751 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]752 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]753 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]754</dl>
755<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]756 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]757 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]758 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]759</dl>
760<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]761 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]762 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]763 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]764</dl>
765<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]766 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]767 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]768 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]769</dl>
770
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]771<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]772
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]773<p>Entities in principle are similar to simple C macros. An entity defines an
774abbreviation for a given string that you can reuse many times throughout the
775content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]776may occur frequently within a document, or to confine the change needed to a
777document to a restricted area in the internal subset of the document (at the
778beginning). Example:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]779<pre>1 &lt;?xml version="1.0"?>
7802 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
7813 &lt;!ENTITY xml "Extensible Markup Language">
7824 ]>
7835 &lt;EXAMPLE>
7846 &amp;xml;
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]7857 &lt;/EXAMPLE></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]786
787<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]788it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]789are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]790predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]791<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
792for the character '>', <strong>&amp;apos;</strong> for the character ''',
793<strong>&amp;quot;</strong> for the character '"', and
794<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]795
796<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]797substitute an entity's content so that you can see the replacement text in
798your application. Or you may prefer to keep entity references as such in the
799content to be able to save the document back without losing this usually
800precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]801entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]802them as saving time). The <a
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]803href="gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]804function allows you to check and change the behaviour, which is to not
805substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]806
807<p>Here is the DOM tree built by libxml for the previous document in the
808default case:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]809<pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]810DOCUMENT
811version=1.0
812 ELEMENT EXAMPLE
813 TEXT
814 content=
815 ENTITY_REF
816 INTERNAL_GENERAL_ENTITY xml
817 content=Extensible Markup Language
818 TEXT
819 content=</pre>
820
821<p>And here is the result when substituting entities:</p>
822<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
823DOCUMENT
824version=1.0
825 ELEMENT EXAMPLE
826 TEXT
827 content= Extensible Markup Language</pre>
828
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]829<p>So, entities or no entities? Basically, it depends on your use case. I
830suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]831entities in your XML document or data if you are not willing to handle the
832entity references elements in the DOM tree.</p>
833
834<p>Note that at save time libxml enforce the conversion of the predefined
835entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]836transparently replace those with chars (i.e., it will not generate entity
837reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]838finding them in the input).</p>
839
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]840<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]841
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]842<p>The libxml library implements <a
843href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
844recognizing namespace contructs in the input, and does namespace lookup
845automatically when building the DOM tree. A namespace declaration is
846associated with an in-memory structure and all elements or attributes within
847that namespace point to it. Hence testing the namespace is a simple and fast
848equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]849
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]850<p>I suggest that people using libxml use a namespace, and declare it in the
851root element of their document as the default namespace. Then they don't need
852to use the prefix in the content but we will have a basis for future semantic
853refinement and merging of data from different sources. This doesn't augment
854significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]855in the long-term. Example:</p>
856<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/">
857 &lt;elem1>...&lt;/elem1>
858 &lt;elem2>...&lt;/elem2>
859&lt;/mydoc></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]860
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]861<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]862have to point to any existing resource on the Web. It will bind all the
863element and atributes with that URL. I suggest to use an URL within a domain
864you control, and that the URL should contain some kind of version information
865if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]866a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]867
868<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]869version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]870and if the version information don't match something you know, warn the user
871and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]872namespace checking on the prefix value. &lt;foo:text> may be exactly the same
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]873as &lt;bar:text> in another document. What really matter is the URI associated
874with the element or the attribute, not the prefix string (which is just a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]875shortcut for the full URI). In libxml element and attributes have a
876<code>ns</code> field pointing to an xmlNs structure detailing the namespace
877prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]878
879<p>@@Interfaces@@</p>
880
881<p>@@Examples@@</p>
882
883<p>Usually people object using namespace in the case of validation, I object
884this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]885so even is you plan to use or currently are using validation I strongly
886suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]887<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]888flexible parsers. Now using namespace to mix and differentiate content coming
889from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]890to provide ways to do this, but this may not be portable or standardized.</p>
891
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]892<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]893
894<p>Well what is validation and what is a DTD ?</p>
895
896<p>Validation is the process of checking a document against a set of
897construction rules, a <strong>DTD</strong> (Document Type Definition) is such
898a set of rules.</p>
899
900<p>The validation process and building DTDs are the two most difficult parts
901of XML life cycle. Briefly a DTD defines all the possibles element to be
902found within your document, what is the formal shape of your document tree (by
903defining the allowed content of an element, either text, a regular expression
904for the allowed list of children, or mixed content i.e. both text and childs).
905The DTD also defines the allowed attributes for all elements and the types of
906the attributes. For more detailed informations, I suggest to read the related
907parts of the XML specification, the examples found under
908gnome-xml/test/valid/dtd and the large amount of books available on XML. The
909dia example in gnome-xml/test/valid should be both simple and complete enough
910to allow you to build your own.</p>
911
912<p>A word of warning, building a good DTD which will fit your needs of your
913application in the long-term is far from trivial, however the extra level of
914quality it can insure is well worth the price for some sets of applications or
915if you already have already a DTD defined for your application field.</p>
916
917<p>The validation is not completely finished but in a (very IMHO) usable
918state. Until a real validation interface is defined the way to do it is to
919define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
920variable to 1, this will of course be changed at some point:</p>
921
922<p>extern int xmlDoValidityCheckingDefaultValue;</p>
923
924<p>...</p>
925
926<p>xmlDoValidityCheckingDefaultValue = 1;</p>
927
928<p></p>
929
930<p>To handle external entities, use the function
931<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
932link in you HTTP/FTP/Entities database library to the standard libxml
933core.</p>
934
935<p>@@interfaces@@</p>
936
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]937<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]938
939<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]940Model</em> this is an API for accessing XML or HTML structured documents.
941Native 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]942be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]943files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]944set of IDL (or Java) interfaces allowing to traverse and manipulate a
945document. The DOM library will allow accessing and modifying "live" documents
946presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]947
948<p><img src="DOM.gif" alt=" DOM.gif "></p>
949
950<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]951embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]952
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]953<p>The current DOM implementation on top of libxml is the <a
954href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
955a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
956Levien</a>.</p>
957
958<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
959
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]960<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]961
962<p>Here is a real size example, where the actual content of the application
963data 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]964a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]965storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
966base</a>:</p>
967<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]968&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
969 &lt;gjob:Jobs>
970
971 &lt;gjob:Job>
972 &lt;gjob:Project ID="3"/>
973 &lt;gjob:Application>GBackup&lt;/gjob:Application>
974 &lt;gjob:Category>Development&lt;/gjob:Category>
975
976 &lt;gjob:Update>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]977 &lt;gjob:Status>Open&lt;/gjob:Status>
978 &lt;gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]979 &lt;gjob:Salary>USD 0.00&lt;/gjob:Salary>
980 &lt;/gjob:Update>
981
982 &lt;gjob:Developers>
983 &lt;gjob:Developer>
984 &lt;/gjob:Developer>
985 &lt;/gjob:Developers>
986
987 &lt;gjob:Contact>
988 &lt;gjob:Person>Nathan Clemons&lt;/gjob:Person>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]989 &lt;gjob:Email>nathan@windsofstorm.net&lt;/gjob:Email>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]990 &lt;gjob:Company>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]991 &lt;/gjob:Company>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]992 &lt;gjob:Organisation>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]993 &lt;/gjob:Organisation>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]994 &lt;gjob:Webpage>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]995 &lt;/gjob:Webpage>
996 &lt;gjob:Snailmail>
997 &lt;/gjob:Snailmail>
998 &lt;gjob:Phone>
999 &lt;/gjob:Phone>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1000 &lt;/gjob:Contact>
1001
1002 &lt;gjob:Requirements>
1003 The program should be released as free software, under the GPL.
1004 &lt;/gjob:Requirements>
1005
1006 &lt;gjob:Skills>
1007 &lt;/gjob:Skills>
1008
1009 &lt;gjob:Details>
1010 A GNOME based system that will allow a superuser to configure
1011 compressed and uncompressed files and/or file systems to be backed
1012 up with a supported media in the system. This should be able to
1013 perform via find commands generating a list of files that are passed
1014 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1015 or via operations performed on the filesystem itself. Email
1016 notification and GUI status display very important.
1017 &lt;/gjob:Details>
1018
1019 &lt;/gjob:Job>
1020
1021 &lt;/gjob:Jobs>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1022&lt;/gjob:Helping></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1023
1024<p>While loading the XML file into an internal DOM tree is a matter of calling
1025only a couple of functions, browsing the tree to gather the informations and
1026generate the internals structures is harder, and more error prone.</p>
1027
1028<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1029structure. For example, the ordering of the attributes is not significant,
1030Cthe XML specification is clear about it. It's also usually a good idea to not
1031be dependent of the orders of the childs of a given node, unless it really
1032makes things harder. Here is some code to parse the informations for a
1033person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1034<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1035 * A person record
1036 */
1037typedef struct person {
1038 char *name;
1039 char *email;
1040 char *company;
1041 char *organisation;
1042 char *smail;
1043 char *webPage;
1044 char *phone;
1045} person, *personPtr;
1046
1047/*
1048 * And the code needed to parse it
1049 */
1050personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1051 personPtr ret = NULL;
1052
1053DEBUG("parsePerson\n");
1054 /*
1055 * allocate the struct
1056 */
1057 ret = (personPtr) malloc(sizeof(person));
1058 if (ret == NULL) {
1059 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1060 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1061 }
1062 memset(ret, 0, sizeof(person));
1063
1064 /* We don't care what the top level element name is */
1065 cur = cur->childs;
1066 while (cur != NULL) {
1067 if ((!strcmp(cur->name, "Person")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1068 ret->name = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1069 if ((!strcmp(cur->name, "Email")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1070 ret->email = xmlNodeListGetString(doc, cur->childs, 1);
1071 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1072 }
1073
1074 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1075}</pre>
1076
1077<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1078<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1079 <li>Usually a recursive parsing style is the more convenient one, XML data
1080 being by nature subject to repetitive constructs and usualy exibit highly
1081 stuctured patterns.</li>
1082 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1083 the pointer to the global XML document and the namespace reserved to the
1084 application. Document wide information are needed for example to decode
1085 entities and it's a good coding practice to define a namespace for your
1086 application set of data and test that the element and attributes you're
1087 analyzing actually pertains to your application space. This is done by a
1088 simple equality test (cur->ns == ns).</li>
1089 <li>To retrieve text and attributes value, it is suggested to use the
1090 function <em>xmlNodeListGetString</em> to gather all the text and entity
1091 reference nodes generated by the DOM output and produce an single text
1092 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1093</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1094
1095<p>Here is another piece of code used to parse another level of the
1096structure:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1097<pre>#include &lt;libxml/tree.h>
1098/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1099 * a Description for a Job
1100 */
1101typedef struct job {
1102 char *projectID;
1103 char *application;
1104 char *category;
1105 personPtr contact;
1106 int nbDevelopers;
1107 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1108} job, *jobPtr;
1109
1110/*
1111 * And the code needed to parse it
1112 */
1113jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1114 jobPtr ret = NULL;
1115
1116DEBUG("parseJob\n");
1117 /*
1118 * allocate the struct
1119 */
1120 ret = (jobPtr) malloc(sizeof(job));
1121 if (ret == NULL) {
1122 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1123 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1124 }
1125 memset(ret, 0, sizeof(job));
1126
1127 /* We don't care what the top level element name is */
1128 cur = cur->childs;
1129 while (cur != NULL) {
1130
1131 if ((!strcmp(cur->name, "Project")) &amp;&amp; (cur->ns == ns)) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1132 ret->projectID = xmlGetProp(cur, "ID");
1133 if (ret->projectID == NULL) {
1134 fprintf(stderr, "Project has no ID\n");
1135 }
1136 }
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1137 if ((!strcmp(cur->name, "Application")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1138 ret->application = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1139 if ((!strcmp(cur->name, "Category")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1140 ret->category = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1141 if ((!strcmp(cur->name, "Contact")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1142 ret->contact = parsePerson(doc, ns, cur);
1143 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1144 }
1145
1146 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1147}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1148
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1149<p>One can notice that once used to it, writing this kind of code is quite
1150simple, but boring. Ultimately, it could be possble to write stubbers taking
1151either C data structure definitions, a set of XML examples or an XML DTD and
1152produce the code needed to import and export the content between C data and
1153XML storage. This is left as an exercise to the reader :-)</p>
1154
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame^]1155<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1156parsing example</a> as a template, it is also available with Makefile in the
1157Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1158
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1159<h2><a name="Contributi">Contributions</a></h2>
1160<ul>
1161 <li><a href="mailto:ari@btigate.com">Ari Johnson</a> provides a C++ wrapper
1162 for libxml:
1163 <p>Website: <a
1164 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1165 <p>Download: <a
1166 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1167 </li>
1168 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1169 precompiled Windows version
1170 <p><a
1171 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1172 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1173 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1174 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1175 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1176 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1177 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1178 integrated in the distribution)</li>
1179</ul>
1180
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1181<p></p>
1182
1183<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1184
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame^]1185<p>$Id: xml.html,v 1.36 2000/07/02 07:56:37 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1186</body>
1187</html>