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blob: a39279e0a4dd5766a938beef42473a9e7121f734 [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 Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V3.1">
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>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]81 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]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 Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]144archive</a> or <a
145href="ftp://ftp.gnome.org/pub/GNOME/contrib/redhat/SRPMS/">RPM packages</a>.
146(NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]147href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
148href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]149packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]150
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]151<p><a name="Snapshot">Snapshot:</a></p>
152<ul>
153 <li>Code from the W3C cvs base libxml <a
154 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
155 <li>Docs, content of the web site, the list archive included <a
156 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
157</ul>
158
159<p><a name="Contribs">Contribs:</a></p>
160
161<p>I do accept external contributions, especially if compiling on another
162platform, get in touch with me to upload the package. I will keep them in the
163<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
164
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]165<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]166<ul>
167 <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]168 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]169 this base for my own development, so it's updated more regularly, but the
170 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]171 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]172 password: anonymous
173 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]174 </li>
175 <li><p>The <a
176 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]177 CVS base</a>. Check the <a
178 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
179 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]180 </li>
181</ul>
182
183<h2><a name="News">News</a></h2>
184
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]185<h3>CVS only : check the <a
186href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
187for really accurate description</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]188<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]189 <li>working on HTML and XML links recognition layers, get in touch with me
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]190 if you want to test those.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]191</ul>
192
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame^]193<h3>2.1.1: July 1 2000</h3>
194<ul>
195 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
196 <li>improvements on the HTML parser</li>
197</ul>
198
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]199<h3>2.1.0 and 1.8.8: June 29 2000</h3>
200<ul>
201 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
202 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
203 about &amp;#38; charref parsing</li>
204 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
205 also contains numerous fixes and enhancements:
206 <ul>
207 <li>added xmlStopParser() to stop parsing</li>
208 <li>improved a lot parsing speed when there is large CDATA blocs</li>
209 <li>includes XPath patches provided by Picdar Technology</li>
210 <li>tried to fix as much as possible DtD validation and namespace
211 related problems</li>
212 <li>output to a given encoding has been added/tested</li>
213 <li>lot of various fixes</li>
214 </ul>
215 </li>
216</ul>
217
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]218<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]219<ul>
220 <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]221 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
222 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
223 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]224 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]225 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]226 <pre>#include &lt;libxml/xxx.h></pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]227 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]228 <pre>#include "xxx.h"</pre>
229 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]230 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
231 <li>the memory allocation routines used by libxml can now be overloaded
232 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]233 <li>The previously CVS only tool tester has been renamed
234 <strong>xmllint</strong> and is now installed as part of the libxml2
235 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]236 <li>The I/O interface has been revamped. There is now ways to plug in
237 specific I/O modules, either at the URI scheme detection level using
238 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
239 parser context using xmlCreateIOParserCtxt()</li>
240 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
241 number of the libxml module in use</li>
242 <li>a number of optional features of libxml can now be excluded at configure
243 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]244</ul>
245
246<h3>2.0.0beta: Mar 14 2000</h3>
247<ul>
248 <li>This is a first Beta release of libxml version 2</li>
249 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
250 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
251 tar and RPMs</li>
252 <li>This version is now the head in the Gnome CVS base, the old one is
253 available under the tag LIB_XML_1_X</li>
254 <li>This includes a very large set of changes. Froma programmatic point of
255 view applications should not have to be modified too much, check the <a
256 href="upgrade.html">upgrade page</a></li>
257 <li>Some interfaces may changes (especially a bit about encoding).</li>
258 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]259 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]260 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
261 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]262 <li>Better handling of entities, especially well formedness checking and
263 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]264 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]265 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]266 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
267 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]268 </ul>
269 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]270 <li>Serious progress were made toward compliance, <a
271 href="conf/result.html">here are the result of the test</a> against the
272 OASIS testsuite (except the japanese tests since I don't support that
273 encoding yet). This URL is rebuilt every couple of hours using the CVS
274 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]275</ul>
276
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]277<h3>1.8.7: Mar 6 2000</h3>
278<ul>
279 <li>This is a bug fix release:</li>
280 <li>It is possible to disable the ignorable blanks heuristic used by
281 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
282 that for adherence to XML spec, this behaviour will be disabled by default
283 in 2.x . The same function will allow to keep compatibility for old
284 code.</li>
285 <li>Blanks in &lt;a> &lt;/a> constructs are not ignored anymore, avoiding
286 heuristic is really the Right Way :-\</li>
287 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
288 compilation on some platforms has been fixed</li>
289 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
290 URIs</li>
291</ul>
292
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]293<h3>1.8.6: Jan 31 2000</h3>
294<ul>
295 <li>added a nanoFTP transport module, debugged until the new version of <a
296 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
297 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]298</ul>
299
300<h3>1.8.5: Jan 21 2000</h3>
301<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]302 <li>adding APIs to parse a well balanced chunk of XML (production <a
303 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
304 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]305 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
306 <li>Jody Goldberg &lt;jgoldberg@home.com> provided another patch trying to
307 solve the zlib checks problems</li>
308 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
309 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]310</ul>
311
312<h3>1.8.4: Jan 13 2000</h3>
313<ul>
314 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
315 <li>all exit() call should have been removed from libxml</li>
316 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
317 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]318</ul>
319
320<h3>1.8.3: Jan 5 2000</h3>
321<ul>
322 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]323 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]324 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]325 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]326 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
327 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]328 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]329 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]330 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]331</ul>
332
333<h3>1.8.2: Dec 21 1999</h3>
334<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]335 <li>I got another problem with includes and C++, I hope this issue is fixed
336 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]337 <li>Added a few tree modification functions: xmlReplaceNode,
338 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
339 xmlDocSetRootElement</li>
340 <li>Tried to improve the HTML output with help from <a
341 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]342</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]343
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]344<h3>1.8.1: Dec 18 1999</h3>
345<ul>
346 <li>various patches to avoid troubles when using libxml with C++ compilers
347 the "namespace" keyword and C escaping in include files</li>
348 <li>a problem in one of the core macros IS_CHAR was corrected</li>
349 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
350 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]351 <li>fixed a posteriori validation (validation after parsing, or by using a
352 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]353 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]354</ul>
355
356<h3>1.8.0: Dec 12 1999</h3>
357<ul>
358 <li>cleanup, especially memory wise</li>
359 <li>the parser should be more reliable, especially the HTML one, it should
360 not crash, whatever the input !</li>
361 <li>Integrated various patches, especially a speedup improvement for large
362 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
363 configure with --with-buffers to enable them.</li>
364 <li>attribute normalization, oops should have been added long ago !</li>
365 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
366 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]367</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]368
369<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]370<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]371 <li>Lots of HTML improvement</li>
372 <li>Fixed some errors when saving both XML and HTML</li>
373 <li>More examples, the regression tests should now look clean</li>
374 <li>Fixed a bug with contiguous charref</li>
375</ul>
376
377<h3>1.7.3: Sep 29 1999</h3>
378<ul>
379 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]380 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]381 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]382</ul>
383
384<h3>1.7.1: Sep 24 1999</h3>
385<ul>
386 <li>The basic type for strings manipulated by libxml has been renamed in
387 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
388 is that CHAR was conflicting with a predefined type on Windows. However on
389 non WIN32 environment, compatibility is provided by the way of a
390 <strong>#define </strong>.</li>
391 <li>Changed another error : the use of a structure field called errno, and
392 leading to troubles on platforms where it's a macro</li>
393</ul>
394
395<h3>1.7.0: sep 23 1999</h3>
396<ul>
397 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]398 href="html/gnome-xml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]399 <li>Added an errno to report errors by another mean than a simple printf
400 like callback</li>
401 <li>Finished ID/IDREF support and checking when validation</li>
402 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]403 href="html/gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]404 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
405 implementation</li>
406 <li>Added an HTML parser front-end</li>
407</ul>
408
409<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]410
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]411<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]412markup-based structured documents. Here is <a name="example">an example XML
413document</a>:</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]414<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]415&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]416 &lt;head>
417 &lt;title>Welcome to Gnome&lt;/title>
418 &lt;/head>
419 &lt;chapter>
420 &lt;title>The Linux adventure&lt;/title>
421 &lt;p>bla bla bla ...&lt;/p>
422 &lt;image href="linus.gif"/>
423 &lt;p>...&lt;/p>
424 &lt;/chapter>
425&lt;/EXAMPLE></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]426
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]427<p>The first line specifies that it's an XML document and gives useful
428information about its encoding. Then the document is a text format whose
429structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]430to be closed</strong>. XML is pedantic about this. However, if a tag is empty
431(no content), a single tag can serve as both the opening and closing tag if it
432ends with <code>/></code> rather than with <code>></code>. Note that, for
433example, the image tag has no content (just an attribute) and is closed by
434ending the tag with <code>/></code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]435
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]436<p>XML can be applied sucessfully to a wide range of uses, from long term
437structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]438data encoding mechanisms like configuration file formatting (glade),
439spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
440it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]441
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]442<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]443
444<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]445returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]446<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]447as the file name, the document type, and a <strong>children</strong> pointer
448which is the root of the document (or more exactly the first child under the
449root which is the document). The tree is made of <strong>xmlNode</strong>s,
450chained in double-linked lists of siblings and with children&lt;->parent
451relationship. An xmlNode can also carry properties (a chain of xmlAttr
452structures). An attribute may have a value which is a list of TEXT or
453ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]454
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]455<p>Here is an example (erroneous with respect to the XML spec since there
456should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]457
458<p><img src="structure.gif" alt=" structure.gif "></p>
459
460<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]461called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]462prints them back as parsed. This is useful for detecting errors both in XML
463code and in the XML parser itself. It has an option <strong>--debug</strong>
464which prints the actual in-memory structure of the document, here is the
465result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]466<pre>DOCUMENT
467version=1.0
468standalone=true
469 ELEMENT EXAMPLE
470 ATTRIBUTE prop1
471 TEXT
472 content=gnome is great
473 ATTRIBUTE prop2
474 ENTITY_REF
475 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]476 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]477 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]478 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]479 TEXT
480 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]481 ELEMENT chapter
482 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]483 TEXT
484 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]485 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]486 TEXT
487 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]488 ELEMENT image
489 ATTRIBUTE href
490 TEXT
491 content=linus.gif
492 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]493 TEXT
494 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]495
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]496<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]497
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]498<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]499
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]500<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]501memory. In that case (and if you don't expect to save back the XML document
502loaded 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]503<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]504application layer registers a customized set of callbacks which are called by
505the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]506
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]507<p>To get more detailed step-by-step guidance on using the SAX interface of
508libxml, see the
509href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]510documentation.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]511Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]512
513<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
514program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]515binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]516distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]517testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]518<pre>SAX.setDocumentLocator()
519SAX.startDocument()
520SAX.getEntity(amp)
521SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
522SAX.characters( , 3)
523SAX.startElement(head)
524SAX.characters( , 4)
525SAX.startElement(title)
526SAX.characters(Welcome to Gnome, 16)
527SAX.endElement(title)
528SAX.characters( , 3)
529SAX.endElement(head)
530SAX.characters( , 3)
531SAX.startElement(chapter)
532SAX.characters( , 4)
533SAX.startElement(title)
534SAX.characters(The Linux adventure, 19)
535SAX.endElement(title)
536SAX.characters( , 4)
537SAX.startElement(p)
538SAX.characters(bla bla bla ..., 15)
539SAX.endElement(p)
540SAX.characters( , 4)
541SAX.startElement(image, href='linus.gif')
542SAX.endElement(image)
543SAX.characters( , 4)
544SAX.startElement(p)
545SAX.characters(..., 3)
546SAX.endElement(p)
547SAX.characters( , 3)
548SAX.endElement(chapter)
549SAX.characters( , 1)
550SAX.endElement(EXAMPLE)
551SAX.endDocument()</pre>
552
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]553<p>Most of the other functionalities of libxml are based on the DOM
554tree-building facility, so nearly everything up to the end of this document
555presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]556itself is built by a set of registered default callbacks, without internal
557specific interface.</p>
558
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]559<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]560
561<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]562using the XML library from the C language. It is not intended to be extensive.
563I hope the automatically generated documents will provide the completeness
564required, but as a separate set of documents. The interfaces of the XML
565library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]566interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]567
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]568<p>The <a href="html/gnome-xml-parser.html">parser interfaces for XML</a> are
569separated from the <a href="html/gnome-xml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]570interfaces</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]571
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]572<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]573
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]574<p>Usually, the first thing to do is to read an XML input. The parser accepts
575documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]576defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]577<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]578 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]579 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]580 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]581</dl>
582<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]583 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]584 <dd><p>Parse an XML document contained in a (possibly compressed)
585 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]586 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]587</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]588
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]589<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]590failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]591
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]592<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]593
594<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]595fetched (which is common for GUI based programs) libxml provides a push
596interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]597<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
598 void *user_data,
599 const char *chunk,
600 int size,
601 const char *filename);
602int xmlParseChunk (xmlParserCtxtPtr ctxt,
603 const char *chunk,
604 int size,
605 int terminate);</pre>
606
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]607<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]608<pre> FILE *f;
609
610 f = fopen(filename, "r");
611 if (f != NULL) {
612 int res, size = 1024;
613 char chars[1024];
614 xmlParserCtxtPtr ctxt;
615
616 res = fread(chars, 1, 4, f);
617 if (res > 0) {
618 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
619 chars, res, filename);
620 while ((res = fread(chars, 1, size, f)) > 0) {
621 xmlParseChunk(ctxt, chars, res, 0);
622 }
623 xmlParseChunk(ctxt, chars, 0, 1);
624 doc = ctxt->myDoc;
625 xmlFreeParserCtxt(ctxt);
626 }
627 }</pre>
628
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]629<p>Also note that the HTML parser embedded into libxml also has a push
630interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]631
632<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
633
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]634<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]635memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]636Reading a document without building the tree is possible using the SAX
637interfaces (see SAX.h and <a
638href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]639Henstridge's documentation</a>). Note also that the push interface can be
640limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]641<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]642
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]643<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]644
645<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]646there is a set of functions dedicated to building new elements. (These are
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]647also described in &lt;libxml/tree.h>.) For example, here is a piece of code
648that produces the XML document used in the previous examples:</p>
649<pre> #include &lt;libxml/tree.h>
650 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]651 xmlNodePtr tree, subtree;
652
653 doc = xmlNewDoc("1.0");
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]654 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
655 xmlSetProp(doc->children, "prop1", "gnome is great");
656 xmlSetProp(doc->children, "prop2", "&amp; linux too");
657 tree = xmlNewChild(doc->children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]658 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]659 tree = xmlNewChild(doc->children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]660 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
661 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
662 subtree = xmlNewChild(tree, NULL, "image", NULL);
663 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]664
665<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]666
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]667<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]668
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]669<p>Basically by <a href="html/gnome-xml-tree.html">including "tree.h"</a> your
670code has access to the internal structure of all the elements of the tree. The
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]671names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]672<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]673<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]674example:</p>
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]675<pre><code>doc->children->children->children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]676
677<p>points to the title element,</p>
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]678<pre>doc->children->children->next->child->child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]679
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]680<p>points to the text node containing the chapter title "The Linux
681adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]682
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]683<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]684present before the document root, so <code>doc->children</code> may point to
685an element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]686<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]687
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]688<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]689
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]690<p>Functions are provided for reading and writing the document content. Here
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]691is 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]692<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]693 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
694 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]695 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
696 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]697 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]698</dl>
699<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]700 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]701 *name);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]702 <dd><p>This function returns a pointer to the property content. Note that
703 no extra copy is made.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]704 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]705</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]706
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]707<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]708elements:</p>
709<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]710 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]711 *value);</code></dt>
712 <dd><p>This function takes an "external" string and convert it to one text
713 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]714 entity references like &amp;Gnome; will be stored internally as entity
715 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]716 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]717</dl>
718<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]719 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]720 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]721 <dd><p>This function is the inverse of
722 <code>xmlStringGetNodeList()</code>. It generates a new string
723 containing the content of the text and entity nodes. Note the extra
724 argument inLine. If this argument is set to 1, the function will expand
725 entity references. For example, instead of returning the &amp;Gnome;
726 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]727 "GNU Network Object Model Environment"). Set this argument if you want
728 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]729 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]730</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]731
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]732<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]733
734<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]735<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]736 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]737 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]738 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]739 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]740</dl>
741<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]742 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]743 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]744 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]745</dl>
746<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]747 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]748 <dd><p>Saves the document to a file. In this case, the compression
749 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]750 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]751</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]752
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]753<h3><a name="Compressio">Compression</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>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]756accesses. The level of compression on saves can be turned on either globally
757or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]758<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]759 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]760 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]761 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]762</dl>
763<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]764 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]765 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]766 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]767</dl>
768<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]769 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]770 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]771 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]772</dl>
773<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]774 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]775 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]776 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]777</dl>
778
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]779<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]780
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]781<p>Entities in principle are similar to simple C macros. An entity defines an
782abbreviation for a given string that you can reuse many times throughout the
783content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]784may occur frequently within a document, or to confine the change needed to a
785document to a restricted area in the internal subset of the document (at the
786beginning). Example:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]787<pre>1 &lt;?xml version="1.0"?>
7882 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
7893 &lt;!ENTITY xml "Extensible Markup Language">
7904 ]>
7915 &lt;EXAMPLE>
7926 &amp;xml;
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]7937 &lt;/EXAMPLE></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]794
795<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]796it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]797are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]798predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]799<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
800for the character '>', <strong>&amp;apos;</strong> for the character ''',
801<strong>&amp;quot;</strong> for the character '"', and
802<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]803
804<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]805substitute an entity's content so that you can see the replacement text in
806your application. Or you may prefer to keep entity references as such in the
807content to be able to save the document back without losing this usually
808precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]809entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]810them as saving time). The <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]811href="html/gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]812function allows you to check and change the behaviour, which is to not
813substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]814
815<p>Here is the DOM tree built by libxml for the previous document in the
816default case:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]817<pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]818DOCUMENT
819version=1.0
820 ELEMENT EXAMPLE
821 TEXT
822 content=
823 ENTITY_REF
824 INTERNAL_GENERAL_ENTITY xml
825 content=Extensible Markup Language
826 TEXT
827 content=</pre>
828
829<p>And here is the result when substituting entities:</p>
830<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
831DOCUMENT
832version=1.0
833 ELEMENT EXAMPLE
834 TEXT
835 content= Extensible Markup Language</pre>
836
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]837<p>So, entities or no entities? Basically, it depends on your use case. I
838suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]839entities in your XML document or data if you are not willing to handle the
840entity references elements in the DOM tree.</p>
841
842<p>Note that at save time libxml enforce the conversion of the predefined
843entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]844transparently replace those with chars (i.e., it will not generate entity
845reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]846finding them in the input).</p>
847
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]848<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]849
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]850<p>The libxml library implements <a
851href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
852recognizing namespace contructs in the input, and does namespace lookup
853automatically when building the DOM tree. A namespace declaration is
854associated with an in-memory structure and all elements or attributes within
855that namespace point to it. Hence testing the namespace is a simple and fast
856equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]857
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]858<p>I suggest that people using libxml use a namespace, and declare it in the
859root element of their document as the default namespace. Then they don't need
860to use the prefix in the content but we will have a basis for future semantic
861refinement and merging of data from different sources. This doesn't augment
862significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]863in the long-term. Example:</p>
864<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/">
865 &lt;elem1>...&lt;/elem1>
866 &lt;elem2>...&lt;/elem2>
867&lt;/mydoc></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]868
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]869<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]870have to point to any existing resource on the Web. It will bind all the
871element and atributes with that URL. I suggest to use an URL within a domain
872you control, and that the URL should contain some kind of version information
873if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]874a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]875
876<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]877version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]878and if the version information don't match something you know, warn the user
879and 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]880namespace checking on the prefix value. &lt;foo:text> may be exactly the same
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]881as &lt;bar:text> in another document. What really matter is the URI associated
882with the element or the attribute, not the prefix string (which is just a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]883shortcut for the full URI). In libxml element and attributes have a
884<code>ns</code> field pointing to an xmlNs structure detailing the namespace
885prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]886
887<p>@@Interfaces@@</p>
888
889<p>@@Examples@@</p>
890
891<p>Usually people object using namespace in the case of validation, I object
892this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]893so even is you plan to use or currently are using validation I strongly
894suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]895<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]896flexible parsers. Now using namespace to mix and differentiate content coming
897from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]898to provide ways to do this, but this may not be portable or standardized.</p>
899
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]900<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]901
902<p>Well what is validation and what is a DTD ?</p>
903
904<p>Validation is the process of checking a document against a set of
905construction rules, a <strong>DTD</strong> (Document Type Definition) is such
906a set of rules.</p>
907
908<p>The validation process and building DTDs are the two most difficult parts
909of XML life cycle. Briefly a DTD defines all the possibles element to be
910found within your document, what is the formal shape of your document tree (by
911defining the allowed content of an element, either text, a regular expression
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]912for the allowed list of children, or mixed content i.e. both text and
913children). The DTD also defines the allowed attributes for all elements and
914the types of the attributes. For more detailed informations, I suggest to read
915the related parts of the XML specification, the examples found under
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]916gnome-xml/test/valid/dtd and the large amount of books available on XML. The
917dia example in gnome-xml/test/valid should be both simple and complete enough
918to allow you to build your own.</p>
919
920<p>A word of warning, building a good DTD which will fit your needs of your
921application in the long-term is far from trivial, however the extra level of
922quality it can insure is well worth the price for some sets of applications or
923if you already have already a DTD defined for your application field.</p>
924
925<p>The validation is not completely finished but in a (very IMHO) usable
926state. Until a real validation interface is defined the way to do it is to
927define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
928variable to 1, this will of course be changed at some point:</p>
929
930<p>extern int xmlDoValidityCheckingDefaultValue;</p>
931
932<p>...</p>
933
934<p>xmlDoValidityCheckingDefaultValue = 1;</p>
935
936<p></p>
937
938<p>To handle external entities, use the function
939<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
940link in you HTTP/FTP/Entities database library to the standard libxml
941core.</p>
942
943<p>@@interfaces@@</p>
944
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]945<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]946
947<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]948Model</em> this is an API for accessing XML or HTML structured documents.
949Native 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]950be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]951files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]952set of IDL (or Java) interfaces allowing to traverse and manipulate a
953document. The DOM library will allow accessing and modifying "live" documents
954presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]955
956<p><img src="DOM.gif" alt=" DOM.gif "></p>
957
958<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]959embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]960
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]961<p>The current DOM implementation on top of libxml is the <a
962href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
963a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
964Levien</a>.</p>
965
966<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
967
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]968<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]969
970<p>Here is a real size example, where the actual content of the application
971data 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]972a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]973storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
974base</a>:</p>
975<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]976&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
977 &lt;gjob:Jobs>
978
979 &lt;gjob:Job>
980 &lt;gjob:Project ID="3"/>
981 &lt;gjob:Application>GBackup&lt;/gjob:Application>
982 &lt;gjob:Category>Development&lt;/gjob:Category>
983
984 &lt;gjob:Update>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]985 &lt;gjob:Status>Open&lt;/gjob:Status>
986 &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]987 &lt;gjob:Salary>USD 0.00&lt;/gjob:Salary>
988 &lt;/gjob:Update>
989
990 &lt;gjob:Developers>
991 &lt;gjob:Developer>
992 &lt;/gjob:Developer>
993 &lt;/gjob:Developers>
994
995 &lt;gjob:Contact>
996 &lt;gjob:Person>Nathan Clemons&lt;/gjob:Person>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]997 &lt;gjob:Email>nathan@windsofstorm.net&lt;/gjob:Email>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]998 &lt;gjob:Company>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]999 &lt;/gjob:Company>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1000 &lt;gjob:Organisation>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1001 &lt;/gjob:Organisation>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1002 &lt;gjob:Webpage>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1003 &lt;/gjob:Webpage>
1004 &lt;gjob:Snailmail>
1005 &lt;/gjob:Snailmail>
1006 &lt;gjob:Phone>
1007 &lt;/gjob:Phone>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1008 &lt;/gjob:Contact>
1009
1010 &lt;gjob:Requirements>
1011 The program should be released as free software, under the GPL.
1012 &lt;/gjob:Requirements>
1013
1014 &lt;gjob:Skills>
1015 &lt;/gjob:Skills>
1016
1017 &lt;gjob:Details>
1018 A GNOME based system that will allow a superuser to configure
1019 compressed and uncompressed files and/or file systems to be backed
1020 up with a supported media in the system. This should be able to
1021 perform via find commands generating a list of files that are passed
1022 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1023 or via operations performed on the filesystem itself. Email
1024 notification and GUI status display very important.
1025 &lt;/gjob:Details>
1026
1027 &lt;/gjob:Job>
1028
1029 &lt;/gjob:Jobs>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1030&lt;/gjob:Helping></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1031
1032<p>While loading the XML file into an internal DOM tree is a matter of calling
1033only a couple of functions, browsing the tree to gather the informations and
1034generate the internals structures is harder, and more error prone.</p>
1035
1036<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1037structure. For example, the ordering of the attributes is not significant,
1038Cthe 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]1039be dependent of the orders of the children of a given node, unless it really
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1040makes things harder. Here is some code to parse the informations for a
1041person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1042<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1043 * A person record
1044 */
1045typedef struct person {
1046 char *name;
1047 char *email;
1048 char *company;
1049 char *organisation;
1050 char *smail;
1051 char *webPage;
1052 char *phone;
1053} person, *personPtr;
1054
1055/*
1056 * And the code needed to parse it
1057 */
1058personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1059 personPtr ret = NULL;
1060
1061DEBUG("parsePerson\n");
1062 /*
1063 * allocate the struct
1064 */
1065 ret = (personPtr) malloc(sizeof(person));
1066 if (ret == NULL) {
1067 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1068 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1069 }
1070 memset(ret, 0, sizeof(person));
1071
1072 /* We don't care what the top level element name is */
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1073 cur = cur->xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1074 while (cur != NULL) {
1075 if ((!strcmp(cur->name, "Person")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1076 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1077 if ((!strcmp(cur->name, "Email")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1078 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1079 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1080 }
1081
1082 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1083}</pre>
1084
1085<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1086<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1087 <li>Usually a recursive parsing style is the more convenient one, XML data
1088 being by nature subject to repetitive constructs and usualy exibit highly
1089 stuctured patterns.</li>
1090 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1091 the pointer to the global XML document and the namespace reserved to the
1092 application. Document wide information are needed for example to decode
1093 entities and it's a good coding practice to define a namespace for your
1094 application set of data and test that the element and attributes you're
1095 analyzing actually pertains to your application space. This is done by a
1096 simple equality test (cur->ns == ns).</li>
1097 <li>To retrieve text and attributes value, it is suggested to use the
1098 function <em>xmlNodeListGetString</em> to gather all the text and entity
1099 reference nodes generated by the DOM output and produce an single text
1100 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1101</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1102
1103<p>Here is another piece of code used to parse another level of the
1104structure:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1105<pre>#include &lt;libxml/tree.h>
1106/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1107 * a Description for a Job
1108 */
1109typedef struct job {
1110 char *projectID;
1111 char *application;
1112 char *category;
1113 personPtr contact;
1114 int nbDevelopers;
1115 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1116} job, *jobPtr;
1117
1118/*
1119 * And the code needed to parse it
1120 */
1121jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1122 jobPtr ret = NULL;
1123
1124DEBUG("parseJob\n");
1125 /*
1126 * allocate the struct
1127 */
1128 ret = (jobPtr) malloc(sizeof(job));
1129 if (ret == NULL) {
1130 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1131 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1132 }
1133 memset(ret, 0, sizeof(job));
1134
1135 /* We don't care what the top level element name is */
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1136 cur = cur->xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1137 while (cur != NULL) {
1138
1139 if ((!strcmp(cur->name, "Project")) &amp;&amp; (cur->ns == ns)) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1140 ret->projectID = xmlGetProp(cur, "ID");
1141 if (ret->projectID == NULL) {
1142 fprintf(stderr, "Project has no ID\n");
1143 }
1144 }
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1145 if ((!strcmp(cur->name, "Application")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1146 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1147 if ((!strcmp(cur->name, "Category")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1148 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1149 if ((!strcmp(cur->name, "Contact")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1150 ret->contact = parsePerson(doc, ns, cur);
1151 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1152 }
1153
1154 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1155}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1156
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1157<p>One can notice that once used to it, writing this kind of code is quite
1158simple, but boring. Ultimately, it could be possble to write stubbers taking
1159either C data structure definitions, a set of XML examples or an XML DTD and
1160produce the code needed to import and export the content between C data and
1161XML storage. This is left as an exercise to the reader :-)</p>
1162
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]1163<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1164parsing example</a> as a template, it is also available with Makefile in the
1165Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1166
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1167<h2><a name="Contributi">Contributions</a></h2>
1168<ul>
1169 <li><a href="mailto:ari@btigate.com">Ari Johnson</a> provides a C++ wrapper
1170 for libxml:
1171 <p>Website: <a
1172 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1173 <p>Download: <a
1174 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1175 </li>
1176 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1177 precompiled Windows version
1178 <p><a
1179 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1180 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1181 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1182 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1183 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1184 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1185 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1186 integrated in the distribution)</li>
1187</ul>
1188
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1189<p></p>
1190
1191<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1192
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame^]1193<p>$Id: xml.html,v 1.39 2000/07/03 12:38:45 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1194</body>
1195</html>