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* doc/site.xsl doc/*.html doc/Makefile.am: now autogenerate the web site from the main HTML document. Daniel
1704 lines
68 KiB
HTML
1704 lines
68 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<title>The XML C library for Gnome</title>
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<meta name="GENERATOR" content="amaya V5.0">
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<meta http-equiv="Content-Type" content="text/html">
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</head>
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<body bgcolor="#ffffff">
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<h1 align="center">The XML C library for Gnome</h1>
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<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
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<p></p>
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<ul>
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<li><a href="#Introducti">Introduction</a></li>
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<li><a href="#Documentat">Documentation</a></li>
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<li><a href="#Reporting">Reporting bugs and getting help</a></li>
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<li><a href="#help">how to help</a></li>
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<li><a href="#Downloads">Downloads</a></li>
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<li><a href="#News">News</a></li>
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<li><a href="#XML">XML</a></li>
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<li><a href="#XSLT">XSLT</a></li>
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<li><a href="#tree">The tree output</a></li>
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<li><a href="#interface">The SAX interface</a></li>
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<li><a href="#library">The XML library interfaces</a></li>
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<li><a href="#Entities">Entities or no entities</a></li>
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<li><a href="#Namespaces">Namespaces</a></li>
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<li><a href="#Validation">Validation</a></li>
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<li><a href="#Principles">DOM principles</a></li>
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<li><a href="#real">A real example</a></li>
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<li><a href="#Contributi">Contributions</a></li>
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</ul>
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<p>Separate documents:</p>
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<ul>
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<li><a href="upgrade.html">upgrade instructions for migrating to
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libxml2</a></li>
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<li><a href="encoding.html">libxml Internationalization support</a></li>
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<li><a href="xmlio.html">libxml Input/Output interfaces</a></li>
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<li><a href="xmlmem.html">libxml Memory interfaces</a></li>
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<li><a href="catalog.html">libxml Catalog support</a></li>
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<li><a href="xmldtd.html">a short introduction about DTDs and
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libxml</a></li>
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<li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a></li>
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<li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page: a
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standard DOM interface for libxml2</a></li>
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</ul>
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<h2><a name="Introducti">Introduction</a></h2>
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<p>This document describes libxml, the <a
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href="http://www.w3.org/XML/">XML</a> C library developped for the <a
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href="http://www.gnome.org/">Gnome</a> project. <a
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href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
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structured documents/data.</p>
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<p>Here are some key points about libxml:</p>
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<ul>
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<li>Libxml exports Push and Pull type parser interfaces for both XML and
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HTML.</li>
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<li>Libxml can do DTD validation at parse time, using a parsed document
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instance, or with an arbitrary DTD.</li>
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<li>Libxml now includes nearly complete <a
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href="http://www.w3.org/TR/xpath">XPath</a>, <a
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href="http://www.w3.org/TR/xptr">XPointer</a> and <a
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href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
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<li>It is written in plain C, making as few assumptions as possible, and
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sticking closely to ANSI C/POSIX for easy embedding. Works on
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Linux/Unix/Windows, ported to a number of other platforms.</li>
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<li>Basic support for HTTP and FTP client allowing aplications to fetch
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remote resources</li>
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<li>The design is modular, most of the extensions can be compiled out.</li>
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<li>The internal document repesentation is as close as possible to the <a
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href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
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<li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
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like interface</a>; the interface is designed to be compatible with <a
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href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
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<li>This library is released both under the <a
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href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
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IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
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LGPL</a>. Use either at your convenience, basically this should make
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everybody happy, if not, drop me a mail.</li>
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</ul>
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<p>Warning: unless you are forced to because your application links with a
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Gnome library requiring it, <strong><span
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style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
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libxml2</p>
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<h2><a name="Documentat">Documentation</a></h2>
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<p>There are some on-line resources about using libxml:</p>
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<ol>
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<li>Check the <a href="FAQ.html">FAQ</a></li>
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<li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
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documentation</a> automatically extracted from code comments (using <a
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href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gtk-doc">gtk
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doc</a>).</li>
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<li>Look at the documentation about <a href="encoding.html">libxml
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internationalization support</a></li>
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<li>This page provides a global overview and <a href="#real">some
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examples</a> on how to use libxml.</li>
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<li><a href="mailto:james@daa.com.au">James Henstridge</a>
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wrote <a
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href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
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documentation</a> explaining how to use the libxml SAX interface.</li>
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<li>George Lebl wrote <a
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href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
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for IBM developerWorks</a> about using libxml.</li>
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<li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
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file</a></li>
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<li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
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starting a new project using libxml you should really use the 2.x
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version.</li>
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<li>And don't forget to look at the <a href="/messages/">mailing-list
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archive</a>.</li>
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</ol>
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<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
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<p>Well, bugs or missing features are always possible, and I will make a
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point of fixing them in a timely fashion. The best way to report a bug is to
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use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
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bug tracking database</a> (make sure to use the "libxml" module name). I look
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at reports there regularly and it's good to have a reminder when a bug is
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still open. Check the <a
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href="http://bugzilla.gnome.org/bugwritinghelp.html">instructions on
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reporting bugs</a> and be sure to specify that the bug is for the package
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libxml.</p>
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<p>There is also a mailing-list <a
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href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
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href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
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href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
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please visit the <a
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href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
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follow the instructions. <strong>Do not send code, I won't debug it</strong>
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(but patches are really appreciated!).</p>
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<p>Check the following <strong><span style="color: #FF0000">before
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posting</span></strong>:</p>
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<ul>
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<li>read the <a href="FAQ.html">FAQ</a></li>
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<li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
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version</a>, and that the problem still shows up in those</li>
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<li>check the <a href="http://mail.gnome.org/archives/xml/">list
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archives</a> to see if the problem was reported already, in this case
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there is probably a fix available, similary check the <a
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href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
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open bugs</a></li>
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<li>make sure you can reproduce the bug with xmllint or one of the test
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programs found in source in the distribution</li>
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<li>Please send the command showing the error as well as the input (as an
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attachement)</li>
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</ul>
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<p>Then send the bug with associated informations to reproduce it to the <a
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href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
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related I will approve it.. Please do not send me mail directly, it makes
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things really harder to track and in some cases I'm not the best person to
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answer a given question, ask the list instead.</p>
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<p>Of course, bugs reported with a suggested patch for fixing them will
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probably be processed faster.</p>
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<p>If you're looking for help, a quick look at <a
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href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
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provide the answer, I usually send source samples when answering libxml usage
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questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
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documentantion</a> is not as polished as I would like (i need to learn more
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about Docbook), but it's a good starting point.</p>
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<h2><a name="help">How to help</a></h2>
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<p>You can help the project in various ways, the best thing to do first is to
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subscribe to the mailing-list as explained before, check the <a
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href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
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href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
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database:</a>:</p>
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<ol>
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<li>provide patches when you find problems</li>
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<li>provide the diffs when you port libxml to a new platform. They may not
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be integrated in all cases but help pinpointing portability problems
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and</li>
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<li>provide documentation fixes (either as patches to the code comments or
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as HTML diffs).</li>
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<li>provide new documentations pieces (translations, examples, etc ...)</li>
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<li>Check the TODO file and try to close one of the items</li>
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<li>take one of the points raised in the archive or the bug database and
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provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
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</a>before to avoid synchronization problems and check that the suggested
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fix will fit in nicely :-)</li>
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</ol>
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<h2><a name="Downloads">Downloads</a></h2>
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<p>The latest versions of libxml can be found on <a
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href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
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href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
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href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
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href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
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as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
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archive</a> or <a
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href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
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packages</a>. (NOTE that you need both the <a
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href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
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href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
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packages installed to compile applications using libxml.) <a
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href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
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of the Windows port, <a
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href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
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provides binaries</a></p>
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<p><a name="Snapshot">Snapshot:</a></p>
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<ul>
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<li>Code from the W3C cvs base libxml <a
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href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
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<li>Docs, content of the web site, the list archive included <a
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href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
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</ul>
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<p><a name="Contribs">Contribs:</a></p>
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<p>I do accept external contributions, especially if compiling on another
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platform, get in touch with me to upload the package. I will keep them in the
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<a href="ftp://xmlsoft.org/contribs/">contrib directory</a></p>
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<p>Libxml is also available from CVS:</p>
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<ul>
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<li><p>The <a
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href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Gnome
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CVS base</a>. Check the <a
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href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
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page; the CVS module is <b>gnome-xml</b>.</p>
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</li>
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<li>The <strong>libxslt</strong> module is also present there</li>
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</ul>
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<h2><a name="News">News</a></h2>
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<h3>CVS only : check the <a
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href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
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for a really accurate description</h3>
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<p>Items floating around but not actively worked on, get in touch with me if
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you want to test those</p>
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<ul>
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<li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
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as a separate C library on top of libxml called libxslt</li>
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<li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
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href="http://www.w3.org/TR/xinclude">XInclude</a></li>
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<li>(seeems working but delayed from release) parsing/import of Docbook
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SGML docs</li>
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</ul>
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<h3>2.4.6: Oct 10 2001</h3>
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<ul>
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<li>added and updated man pages by John Fleck</li>
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<li>portability and configure fixes</li>
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<li>an infinite loop on the HTML parser was removed (William)</li>
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<li>Windows makefile patches from Igor</li>
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<li>fixed half a dozen bugs reported fof libxml or libxslt</li>
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<li>updated xmlcatalog to be able to modify SGML super catalogs</li>
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</ul>
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<h3>2.4.5: Sep 14 2001</h3>
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<ul>
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<li>Remove a few annoying bugs in 2.4.4</li>
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<li>forces the HTML serializer to output decimal charrefs since some
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version of Netscape can't handle hexadecimal ones</li>
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</ul>
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<h3>1.8.16: Sep 14 2001</h3>
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<ul>
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<li>maintenance release of the old libxml1 branch, couple of bug and
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portability fixes</li>
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</ul>
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<h3>2.4.4: Sep 12 2001</h3>
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<ul>
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<li>added --convert to xmlcatalog, bug fixes and cleanups of XML
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Catalog</li>
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<li>a few bug fixes and some portability changes</li>
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<li>some documentation cleanups</li>
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</ul>
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<h3>2.4.3: Aug 23 2001</h3>
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<ul>
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<li>XML Catalog support see the doc</li>
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<li>New NaN/Infinity floating point code</li>
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<li>A few bug fixes</li>
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</ul>
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<h3>2.4.2: Aug 15 2001</h3>
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<ul>
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<li>adds xmlLineNumbersDefault() to control line number generation</li>
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<li>lot of bug fixes</li>
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<li>the Microsoft MSC projects files shuld now be up to date</li>
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<li>inheritance of namespaces from DTD defaulted attributes</li>
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<li>fixes a serious potential security bug</li>
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<li>added a --format option to xmllint</li>
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</ul>
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<h3>2.4.1: July 24 2001</h3>
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<ul>
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<li>possibility to keep line numbers in the tree</li>
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<li>some computation NaN fixes</li>
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<li>extension of the XPath API</li>
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||
<li>cleanup for alpha and ia64 targets</li>
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||
<li>patch to allow saving through HTTP PUT or POST</li>
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||
</ul>
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||
<h3>2.4.0: July 10 2001</h3>
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||
<ul>
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||
<li>Fixed a few bugs in XPath, validation, and tree handling.</li>
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||
<li>Fixed XML Base implementation, added a coupel of examples to the
|
||
regression tests</li>
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||
<li>A bit of cleanup</li>
|
||
</ul>
|
||
|
||
<h3>2.3.14: July 5 2001</h3>
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||
<ul>
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||
<li>fixed some entities problems and reduce mem requirement when
|
||
substituing them</li>
|
||
<li>lots of improvements in the XPath queries interpreter can be
|
||
substancially faster</li>
|
||
<li>Makefiles and configure cleanups</li>
|
||
<li>Fixes to XPath variable eval, and compare on empty node set</li>
|
||
<li>HTML tag closing bug fixed</li>
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||
<li>Fixed an URI reference computating problem when validating</li>
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||
</ul>
|
||
|
||
<h3>2.3.13: June 28 2001</h3>
|
||
<ul>
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||
<li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
|
||
<li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
|
||
</ul>
|
||
|
||
<h3>1.8.14: June 28 2001</h3>
|
||
<ul>
|
||
<li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
|
||
<li>Small Makefile fix</li>
|
||
</ul>
|
||
|
||
<h3>2.3.12: June 26 2001</h3>
|
||
<ul>
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||
<li>lots of cleanup</li>
|
||
<li>a couple of validation fix</li>
|
||
<li>fixed line number counting</li>
|
||
<li>fixed serious problems in the XInclude processing</li>
|
||
<li>added support for UTF8 BOM at beginning of entities</li>
|
||
<li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
|
||
miscompile uri.c (William), Thomas Leitner provided a fix for the
|
||
optimizer on Tru64</li>
|
||
<li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
|
||
compilation on Windows MSC</li>
|
||
<li>update of libxml-doc.el (Felix Natter)</li>
|
||
<li>fixed 2 bugs in URI normalization code</li>
|
||
</ul>
|
||
|
||
<h3>2.3.11: June 17 2001</h3>
|
||
<ul>
|
||
<li>updates to trio, Makefiles and configure should fix some portability
|
||
problems (alpha)</li>
|
||
<li>fixed some HTML serialization problems (pre, script, and block/inline
|
||
handling), added encoding aware APIs, cleanup of this code</li>
|
||
<li>added xmlHasNsProp()</li>
|
||
<li>implemented a specific PI for encoding support in the DocBook SGML
|
||
parser</li>
|
||
<li>some XPath fixes (-Infinity, / as a function parameter and namespaces
|
||
node selection)</li>
|
||
<li>fixed a performance problem and an error in the validation code</li>
|
||
<li>fixed XInclude routine to implement the recursive behaviour</li>
|
||
<li>fixed xmlFreeNode problem when libxml is included statically twice</li>
|
||
<li>added --version to xmllint for bug reports</li>
|
||
</ul>
|
||
|
||
<h3>2.3.10: June 1 2001</h3>
|
||
<ul>
|
||
<li>fixed the SGML catalog support</li>
|
||
<li>a number of reported bugs got fixed, in XPath, iconv detection,
|
||
XInclude processing</li>
|
||
<li>XPath string function should now handle unicode correctly</li>
|
||
</ul>
|
||
|
||
<h3>2.3.9: May 19 2001</h3>
|
||
|
||
<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
|
||
<ul>
|
||
<li>HTML push bugfix #54891 and another patch from Jonas Borgstr<74>m</li>
|
||
<li>some serious speed optimisation again</li>
|
||
<li>some documentation cleanups</li>
|
||
<li>trying to get better linking on solaris (-R)</li>
|
||
<li>XPath API cleanup from Thomas Broyer</li>
|
||
<li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
|
||
xmlValidGetValidElements()</li>
|
||
<li>Added an INSTALL file</li>
|
||
<li>Attribute removal added to API: #54433</li>
|
||
<li>added a basic support for SGML catalogs</li>
|
||
<li>fixed xmlKeepBlanksDefault(0) API</li>
|
||
<li>bugfix in xmlNodeGetLang()</li>
|
||
<li>fixed a small configure portability problem</li>
|
||
<li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
|
||
</ul>
|
||
|
||
<h3>1.8.13: May 14 2001</h3>
|
||
<ul>
|
||
<li>bugfixes release of the old libxml1 branch used by Gnome</li>
|
||
</ul>
|
||
|
||
<h3>2.3.8: May 3 2001</h3>
|
||
<ul>
|
||
<li>Integrated an SGML DocBook parser for the Gnome project</li>
|
||
<li>Fixed a few things in the HTML parser</li>
|
||
<li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
|
||
point portability issue</li>
|
||
<li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
|
||
DOM+validation using the XML REC as input and a 700MHz celeron).</li>
|
||
<li>incorporated more Windows cleanup</li>
|
||
<li>added xmlSaveFormatFile()</li>
|
||
<li>fixed problems in copying nodes with entities references (gdome)</li>
|
||
<li>removed some troubles surrounding the new validation module</li>
|
||
</ul>
|
||
|
||
<h3>2.3.7: April 22 2001</h3>
|
||
<ul>
|
||
<li>lots of small bug fixes, corrected XPointer</li>
|
||
<li>Non determinist content model validation support</li>
|
||
<li>added xmlDocCopyNode for gdome2</li>
|
||
<li>revamped the way the HTML parser handles end of tags</li>
|
||
<li>XPath: corrctions of namespacessupport and number formatting</li>
|
||
<li>Windows: Igor Zlatkovic patches for MSC compilation</li>
|
||
<li>HTML ouput fixes from P C Chow and William M. Brack</li>
|
||
<li>Improved validation speed sensible for DocBook</li>
|
||
<li>fixed a big bug with ID declared in external parsed entities</li>
|
||
<li>portability fixes, update of Trio from Bjorn Reese</li>
|
||
</ul>
|
||
|
||
<h3>2.3.6: April 8 2001</h3>
|
||
<ul>
|
||
<li>Code cleanup using extreme gcc compiler warning options, found and
|
||
cleared half a dozen potential problem</li>
|
||
<li>the Eazel team found an XML parser bug</li>
|
||
<li>cleaned up the user of some of the string formatting function. used the
|
||
trio library code to provide the one needed when the platform is missing
|
||
them</li>
|
||
<li>xpath: removed a memory leak and fixed the predicate evaluation
|
||
problem, extended the testsuite and cleaned up the result. XPointer seems
|
||
broken ...</li>
|
||
</ul>
|
||
|
||
<h3>2.3.5: Mar 23 2001</h3>
|
||
<ul>
|
||
<li>Biggest change is separate parsing and evaluation of XPath expressions,
|
||
there is some new APIs for this too</li>
|
||
<li>included a number of bug fixes(XML push parser, 51876, notations,
|
||
52299)</li>
|
||
<li>Fixed some portability issues</li>
|
||
</ul>
|
||
|
||
<h3>2.3.4: Mar 10 2001</h3>
|
||
<ul>
|
||
<li>Fixed bugs #51860 and #51861</li>
|
||
<li>Added a global variable xmlDefaultBufferSize to allow default buffer
|
||
size to be application tunable.</li>
|
||
<li>Some cleanup in the validation code, still a bug left and this part
|
||
should probably be rewritten to support ambiguous content model :-\</li>
|
||
<li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
|
||
parser</li>
|
||
<li>Fixed another bug in xmlNodeGetContent()</li>
|
||
<li>Bjorn fixed XPath node collection and Number formatting</li>
|
||
<li>Fixed a loop reported in the HTML parsing</li>
|
||
<li>blank space are reported even if the Dtd content model proves that they
|
||
are formatting spaces, this is for XmL conformance</li>
|
||
</ul>
|
||
|
||
<h3>2.3.3: Mar 1 2001</h3>
|
||
<ul>
|
||
<li>small change in XPath for XSLT</li>
|
||
<li>documentation cleanups</li>
|
||
<li>fix in validation by Gary Pennington</li>
|
||
<li>serious parsing performances improvements</li>
|
||
</ul>
|
||
|
||
<h3>2.3.2: Feb 24 2001</h3>
|
||
<ul>
|
||
<li>chasing XPath bugs, found a bunch, completed some TODO</li>
|
||
<li>fixed a Dtd parsing bug</li>
|
||
<li>fixed a bug in xmlNodeGetContent</li>
|
||
<li>ID/IDREF support partly rewritten by Gary Pennington</li>
|
||
</ul>
|
||
|
||
<h3>2.3.1: Feb 15 2001</h3>
|
||
<ul>
|
||
<li>some XPath and HTML bug fixes for XSLT</li>
|
||
<li>small extension of the hash table interfaces for DOM gdome2
|
||
implementation</li>
|
||
<li>A few bug fixes</li>
|
||
</ul>
|
||
|
||
<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3>
|
||
<ul>
|
||
<li>Lots of XPath bug fixes</li>
|
||
<li>Add a mode with Dtd lookup but without validation error reporting for
|
||
XSLT</li>
|
||
<li>Add support for text node without escaping (XSLT)</li>
|
||
<li>bug fixes for xmlCheckFilename</li>
|
||
<li>validation code bug fixes from Gary Pennington</li>
|
||
<li>Patch from Paul D. Smith correcting URI path normalization</li>
|
||
<li>Patch to allow simultaneous install of libxml-devel and
|
||
libxml2-devel</li>
|
||
<li>the example Makefile is now fixed</li>
|
||
<li>added HTML to the RPM packages</li>
|
||
<li>tree copying bugfixes</li>
|
||
<li>updates to Windows makefiles</li>
|
||
<li>optimisation patch from Bjorn Reese</li>
|
||
</ul>
|
||
|
||
<h3>2.2.11: Jan 4 2001</h3>
|
||
<ul>
|
||
<li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
|
||
<li>added htmlHandleOmittedElem()</li>
|
||
<li>Applied Bjorn Reese's IPV6 first patch</li>
|
||
<li>Applied Paul D. Smith patches for validation of XInclude results</li>
|
||
<li>added XPointer xmlns() new scheme support</li>
|
||
</ul>
|
||
|
||
<h3>2.2.10: Nov 25 2000</h3>
|
||
<ul>
|
||
<li>Fix the Windows problems of 2.2.8</li>
|
||
<li>integrate OpenVMS patches</li>
|
||
<li>better handling of some nasty HTML input</li>
|
||
<li>Improved the XPointer implementation</li>
|
||
<li>integrate a number of provided patches</li>
|
||
</ul>
|
||
|
||
<h3>2.2.9: Nov 25 2000</h3>
|
||
<ul>
|
||
<li>erroneous release :-(</li>
|
||
</ul>
|
||
|
||
<h3>2.2.8: Nov 13 2000</h3>
|
||
<ul>
|
||
<li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
|
||
support</li>
|
||
<li>Patch in conditional section handling</li>
|
||
<li>updated MS compiler project</li>
|
||
<li>fixed some XPath problems</li>
|
||
<li>added an URI escaping function</li>
|
||
<li>some other bug fixes</li>
|
||
</ul>
|
||
|
||
<h3>2.2.7: Oct 31 2000</h3>
|
||
<ul>
|
||
<li>added message redirection</li>
|
||
<li>XPath improvements (thanks TOM !)</li>
|
||
<li>xmlIOParseDTD() added</li>
|
||
<li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
|
||
<li>some cleanup of the Makefile, autoconf and the distribution content</li>
|
||
</ul>
|
||
|
||
<h3>2.2.6: Oct 25 2000:</h3>
|
||
<ul>
|
||
<li>Added an hash table module, migrated a number of internal structure to
|
||
those</li>
|
||
<li>Fixed a posteriori validation problems</li>
|
||
<li>HTTP module cleanups</li>
|
||
<li>HTML parser improvements (tag errors, script/style handling, attribute
|
||
normalization)</li>
|
||
<li>coalescing of adjacent text nodes</li>
|
||
<li>couple of XPath bug fixes, exported the internal API</li>
|
||
</ul>
|
||
|
||
<h3>2.2.5: Oct 15 2000:</h3>
|
||
<ul>
|
||
<li>XPointer implementation and testsuite</li>
|
||
<li>Lot of XPath fixes, added variable and functions registration, more
|
||
tests</li>
|
||
<li>Portability fixes, lots of enhancements toward an easy Windows build
|
||
and release</li>
|
||
<li>Late validation fixes</li>
|
||
<li>Integrated a lot of contributed patches</li>
|
||
<li>added memory management docs</li>
|
||
<li>a performance problem when using large buffer seems fixed</li>
|
||
</ul>
|
||
|
||
<h3>2.2.4: Oct 1 2000:</h3>
|
||
<ul>
|
||
<li>main XPath problem fixed</li>
|
||
<li>Integrated portability patches for Windows</li>
|
||
<li>Serious bug fixes on the URI and HTML code</li>
|
||
</ul>
|
||
|
||
<h3>2.2.3: Sep 17 2000</h3>
|
||
<ul>
|
||
<li>bug fixes</li>
|
||
<li>cleanup of entity handling code</li>
|
||
<li>overall review of all loops in the parsers, all sprintf usage has been
|
||
checked too</li>
|
||
<li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
|
||
works smoothly now.</li>
|
||
</ul>
|
||
|
||
<h3>1.8.10: Sep 6 2000</h3>
|
||
<ul>
|
||
<li>bug fix release for some Gnome projects</li>
|
||
</ul>
|
||
|
||
<h3>2.2.2: August 12 2000</h3>
|
||
<ul>
|
||
<li>mostly bug fixes</li>
|
||
<li>started adding routines to access xml parser context options</li>
|
||
</ul>
|
||
|
||
<h3>2.2.1: July 21 2000</h3>
|
||
<ul>
|
||
<li>a purely bug fixes release</li>
|
||
<li>fixed an encoding support problem when parsing from a memory block</li>
|
||
<li>fixed a DOCTYPE parsing problem</li>
|
||
<li>removed a bug in the function allowing to override the memory
|
||
allocation routines</li>
|
||
</ul>
|
||
|
||
<h3>2.2.0: July 14 2000</h3>
|
||
<ul>
|
||
<li>applied a lot of portability fixes</li>
|
||
<li>better encoding support/cleanup and saving (content is now always
|
||
encoded in UTF-8)</li>
|
||
<li>the HTML parser now correctly handles encodings</li>
|
||
<li>added xmlHasProp()</li>
|
||
<li>fixed a serious problem with &#38;</li>
|
||
<li>propagated the fix to FTP client</li>
|
||
<li>cleanup, bugfixes, etc ...</li>
|
||
<li>Added a page about <a href="encoding.html">libxml Internationalization
|
||
support</a></li>
|
||
</ul>
|
||
|
||
<h3>1.8.9: July 9 2000</h3>
|
||
<ul>
|
||
<li>fixed the spec the RPMs should be better</li>
|
||
<li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
|
||
rpmfind users problem</li>
|
||
</ul>
|
||
|
||
<h3>2.1.1: July 1 2000</h3>
|
||
<ul>
|
||
<li>fixes a couple of bugs in the 2.1.0 packaging</li>
|
||
<li>improvements on the HTML parser</li>
|
||
</ul>
|
||
|
||
<h3>2.1.0 and 1.8.8: June 29 2000</h3>
|
||
<ul>
|
||
<li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
|
||
<a href="upgrade.html">new instructions</a>. It fixes a nasty problem
|
||
about &#38; charref parsing</li>
|
||
<li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
|
||
also contains numerous fixes and enhancements:
|
||
<ul>
|
||
<li>added xmlStopParser() to stop parsing</li>
|
||
<li>improved a lot parsing speed when there is large CDATA blocs</li>
|
||
<li>includes XPath patches provided by Picdar Technology</li>
|
||
<li>tried to fix as much as possible DtD validation and namespace
|
||
related problems</li>
|
||
<li>output to a given encoding has been added/tested</li>
|
||
<li>lot of various fixes</li>
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
|
||
<h3>2.0.0: Apr 12 2000</h3>
|
||
<ul>
|
||
<li>First public release of libxml2. If you are using libxml, it's a good
|
||
idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
|
||
scheduled for Apr 3 the relase occured only on Apr 12 due to massive
|
||
workload.</li>
|
||
<li>The include are now located under $prefix/include/libxml (instead of
|
||
$prefix/include/gnome-xml), they also are referenced by
|
||
<pre>#include <libxml/xxx.h></pre>
|
||
<p>instead of</p>
|
||
<pre>#include "xxx.h"</pre>
|
||
</li>
|
||
<li>a new URI module for parsing URIs and following strictly RFC 2396</li>
|
||
<li>the memory allocation routines used by libxml can now be overloaded
|
||
dynamically by using xmlMemSetup()</li>
|
||
<li>The previously CVS only tool tester has been renamed
|
||
<strong>xmllint</strong> and is now installed as part of the libxml2
|
||
package</li>
|
||
<li>The I/O interface has been revamped. There is now ways to plug in
|
||
specific I/O modules, either at the URI scheme detection level using
|
||
xmlRegisterInputCallbacks() or by passing I/O functions when creating a
|
||
parser context using xmlCreateIOParserCtxt()</li>
|
||
<li>there is a C preprocessor macro LIBXML_VERSION providing the version
|
||
number of the libxml module in use</li>
|
||
<li>a number of optional features of libxml can now be excluded at
|
||
configure time (FTP/HTTP/HTML/XPath/Debug)</li>
|
||
</ul>
|
||
|
||
<h3>2.0.0beta: Mar 14 2000</h3>
|
||
<ul>
|
||
<li>This is a first Beta release of libxml version 2</li>
|
||
<li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
|
||
FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
|
||
RPMs</li>
|
||
<li>This version is now the head in the Gnome CVS base, the old one is
|
||
available under the tag LIB_XML_1_X</li>
|
||
<li>This includes a very large set of changes. Froma programmatic point of
|
||
view applications should not have to be modified too much, check the <a
|
||
href="upgrade.html">upgrade page</a></li>
|
||
<li>Some interfaces may changes (especially a bit about encoding).</li>
|
||
<li>the updates includes:
|
||
<ul>
|
||
<li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
|
||
handled now</li>
|
||
<li>Better handling of entities, especially well formedness checking
|
||
and proper PEref extensions in external subsets</li>
|
||
<li>DTD conditional sections</li>
|
||
<li>Validation now correcly handle entities content</li>
|
||
<li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
|
||
structures to accomodate DOM</a></li>
|
||
</ul>
|
||
</li>
|
||
<li>Serious progress were made toward compliance, <a
|
||
href="conf/result.html">here are the result of the test</a> against the
|
||
OASIS testsuite (except the japanese tests since I don't support that
|
||
encoding yet). This URL is rebuilt every couple of hours using the CVS
|
||
head version.</li>
|
||
</ul>
|
||
|
||
<h3>1.8.7: Mar 6 2000</h3>
|
||
<ul>
|
||
<li>This is a bug fix release:</li>
|
||
<li>It is possible to disable the ignorable blanks heuristic used by
|
||
libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
|
||
that for adherence to XML spec, this behaviour will be disabled by
|
||
default in 2.x . The same function will allow to keep compatibility for
|
||
old code.</li>
|
||
<li>Blanks in <a> </a> constructs are not ignored anymore,
|
||
avoiding heuristic is really the Right Way :-\</li>
|
||
<li>The unchecked use of snprintf which was breaking libxml-1.8.6
|
||
compilation on some platforms has been fixed</li>
|
||
<li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
|
||
URIs</li>
|
||
</ul>
|
||
|
||
<h3>1.8.6: Jan 31 2000</h3>
|
||
<ul>
|
||
<li>added a nanoFTP transport module, debugged until the new version of <a
|
||
href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
|
||
it without troubles</li>
|
||
</ul>
|
||
|
||
<h3>1.8.5: Jan 21 2000</h3>
|
||
<ul>
|
||
<li>adding APIs to parse a well balanced chunk of XML (production <a
|
||
href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
|
||
XML spec)</li>
|
||
<li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
|
||
<li>Jody Goldberg <jgoldberg@home.com> provided another patch trying
|
||
to solve the zlib checks problems</li>
|
||
<li>The current state in gnome CVS base is expected to ship as 1.8.5 with
|
||
gnumeric soon</li>
|
||
</ul>
|
||
|
||
<h3>1.8.4: Jan 13 2000</h3>
|
||
<ul>
|
||
<li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
|
||
<li>all exit() call should have been removed from libxml</li>
|
||
<li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
|
||
<li>added newDocFragment()</li>
|
||
</ul>
|
||
|
||
<h3>1.8.3: Jan 5 2000</h3>
|
||
<ul>
|
||
<li>a Push interface for the XML and HTML parsers</li>
|
||
<li>a shell-like interface to the document tree (try tester --shell :-)</li>
|
||
<li>lots of bug fixes and improvement added over XMas hollidays</li>
|
||
<li>fixed the DTD parsing code to work with the xhtml DTD</li>
|
||
<li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
|
||
<li>Fixed bugs in xmlNewNs()</li>
|
||
<li>External entity loading code has been revamped, now it uses
|
||
xmlLoadExternalEntity(), some fix on entities processing were added</li>
|
||
<li>cleaned up WIN32 includes of socket stuff</li>
|
||
</ul>
|
||
|
||
<h3>1.8.2: Dec 21 1999</h3>
|
||
<ul>
|
||
<li>I got another problem with includes and C++, I hope this issue is fixed
|
||
for good this time</li>
|
||
<li>Added a few tree modification functions: xmlReplaceNode,
|
||
xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
|
||
xmlDocSetRootElement</li>
|
||
<li>Tried to improve the HTML output with help from <a
|
||
href="mailto:clahey@umich.edu">Chris Lahey</a></li>
|
||
</ul>
|
||
|
||
<h3>1.8.1: Dec 18 1999</h3>
|
||
<ul>
|
||
<li>various patches to avoid troubles when using libxml with C++ compilers
|
||
the "namespace" keyword and C escaping in include files</li>
|
||
<li>a problem in one of the core macros IS_CHAR was corrected</li>
|
||
<li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
|
||
and more specifically the Dia application</li>
|
||
<li>fixed a posteriori validation (validation after parsing, or by using a
|
||
Dtd not specified in the original document)</li>
|
||
<li>fixed a bug in</li>
|
||
</ul>
|
||
|
||
<h3>1.8.0: Dec 12 1999</h3>
|
||
<ul>
|
||
<li>cleanup, especially memory wise</li>
|
||
<li>the parser should be more reliable, especially the HTML one, it should
|
||
not crash, whatever the input !</li>
|
||
<li>Integrated various patches, especially a speedup improvement for large
|
||
dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
|
||
configure with --with-buffers to enable them.</li>
|
||
<li>attribute normalization, oops should have been added long ago !</li>
|
||
<li>attributes defaulted from Dtds should be available, xmlSetProp() now
|
||
does entities escapting by default.</li>
|
||
</ul>
|
||
|
||
<h3>1.7.4: Oct 25 1999</h3>
|
||
<ul>
|
||
<li>Lots of HTML improvement</li>
|
||
<li>Fixed some errors when saving both XML and HTML</li>
|
||
<li>More examples, the regression tests should now look clean</li>
|
||
<li>Fixed a bug with contiguous charref</li>
|
||
</ul>
|
||
|
||
<h3>1.7.3: Sep 29 1999</h3>
|
||
<ul>
|
||
<li>portability problems fixed</li>
|
||
<li>snprintf was used unconditionnally, leading to link problems on system
|
||
were it's not available, fixed</li>
|
||
</ul>
|
||
|
||
<h3>1.7.1: Sep 24 1999</h3>
|
||
<ul>
|
||
<li>The basic type for strings manipulated by libxml has been renamed in
|
||
1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
|
||
is that CHAR was conflicting with a predefined type on Windows. However
|
||
on non WIN32 environment, compatibility is provided by the way of a
|
||
<strong>#define </strong>.</li>
|
||
<li>Changed another error : the use of a structure field called errno, and
|
||
leading to troubles on platforms where it's a macro</li>
|
||
</ul>
|
||
|
||
<h3>1.7.0: sep 23 1999</h3>
|
||
<ul>
|
||
<li>Added the ability to fetch remote DTD or parsed entities, see the <a
|
||
href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
|
||
<li>Added an errno to report errors by another mean than a simple printf
|
||
like callback</li>
|
||
<li>Finished ID/IDREF support and checking when validation</li>
|
||
<li>Serious memory leaks fixed (there is now a <a
|
||
href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
|
||
<li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
|
||
implementation</li>
|
||
<li>Added an HTML parser front-end</li>
|
||
</ul>
|
||
|
||
<h2><a name="XML">XML</a></h2>
|
||
|
||
<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
|
||
markup-based structured documents. Here is <a name="example">an example XML
|
||
document</a>:</p>
|
||
<pre><?xml version="1.0"?>
|
||
<EXAMPLE prop1="gnome is great" prop2="&amp; linux too">
|
||
<head>
|
||
<title>Welcome to Gnome</title>
|
||
</head>
|
||
<chapter>
|
||
<title>The Linux adventure</title>
|
||
<p>bla bla bla ...</p>
|
||
<image href="linus.gif"/>
|
||
<p>...</p>
|
||
</chapter>
|
||
</EXAMPLE></pre>
|
||
|
||
<p>The first line specifies that it's an XML document and gives useful
|
||
information about its encoding. Then the document is a text format whose
|
||
structure is specified by tags between brackets. <strong>Each tag opened has
|
||
to be closed</strong>. XML is pedantic about this. However, if a tag is empty
|
||
(no content), a single tag can serve as both the opening and closing tag if
|
||
it ends with <code>/></code> rather than with <code>></code>. Note
|
||
that, for example, the image tag has no content (just an attribute) and is
|
||
closed by ending the tag with <code>/></code>.</p>
|
||
|
||
<p>XML can be applied sucessfully to a wide range of uses, from long term
|
||
structured document maintenance (where it follows the steps of SGML) to
|
||
simple data encoding mechanisms like configuration file formatting (glade),
|
||
spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
|
||
it is used to encode remote calls between a client and a server.</p>
|
||
|
||
<h2><a name="XSLT">XSLT</a></h2>
|
||
|
||
<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
|
||
|
||
<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
|
||
language for transforming XML documents into other XML documents (or
|
||
HTML/textual output).</p>
|
||
|
||
<p>A separate library called libxslt is being built on top of libxml2. This
|
||
module "libxslt" can be found in the Gnome CVS base too.</p>
|
||
|
||
<p>You can check the <a
|
||
href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
|
||
supported and the progresses on the <a
|
||
href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
|
||
|
||
<h2><a name="architecture">An overview of libxml architecture</a></h2>
|
||
|
||
<p>Libxml is made of multiple components; some of them are optional, and most
|
||
of the block interfaces are public. The main components are:</p>
|
||
<ul>
|
||
<li>an Input/Output layer</li>
|
||
<li>FTP and HTTP client layers (optional)</li>
|
||
<li>an Internationalization layer managing the encodings support</li>
|
||
<li>a URI module</li>
|
||
<li>the XML parser and its basic SAX interface</li>
|
||
<li>an HTML parser using the same SAX interface (optional)</li>
|
||
<li>a SAX tree module to build an in-memory DOM representation</li>
|
||
<li>a tree module to manipulate the DOM representation</li>
|
||
<li>a validation module using the DOM representation (optional)</li>
|
||
<li>an XPath module for global lookup in a DOM representation
|
||
(optional)</li>
|
||
<li>a debug module (optional)</li>
|
||
</ul>
|
||
|
||
<p>Graphically this gives the following:</p>
|
||
|
||
<p><img src="libxml.gif" alt="a graphical view of the various"></p>
|
||
|
||
<p></p>
|
||
|
||
<h2><a name="tree">The tree output</a></h2>
|
||
|
||
<p>The parser returns a tree built during the document analysis. The value
|
||
returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
|
||
<strong>xmlDoc</strong> structure). This structure contains information such
|
||
as the file name, the document type, and a <strong>children</strong> pointer
|
||
which is the root of the document (or more exactly the first child under the
|
||
root which is the document). The tree is made of <strong>xmlNode</strong>s,
|
||
chained in double-linked lists of siblings and with a children<->parent
|
||
relationship. An xmlNode can also carry properties (a chain of xmlAttr
|
||
structures). An attribute may have a value which is a list of TEXT or
|
||
ENTITY_REF nodes.</p>
|
||
|
||
<p>Here is an example (erroneous with respect to the XML spec since there
|
||
should be only one ELEMENT under the root):</p>
|
||
|
||
<p><img src="structure.gif" alt=" structure.gif "></p>
|
||
|
||
<p>In the source package there is a small program (not installed by default)
|
||
called <strong>xmllint</strong> which parses XML files given as argument and
|
||
prints them back as parsed. This is useful for detecting errors both in XML
|
||
code and in the XML parser itself. It has an option <strong>--debug</strong>
|
||
which prints the actual in-memory structure of the document; here is the
|
||
result with the <a href="#example">example</a> given before:</p>
|
||
<pre>DOCUMENT
|
||
version=1.0
|
||
standalone=true
|
||
ELEMENT EXAMPLE
|
||
ATTRIBUTE prop1
|
||
TEXT
|
||
content=gnome is great
|
||
ATTRIBUTE prop2
|
||
ENTITY_REF
|
||
TEXT
|
||
content= linux too
|
||
ELEMENT head
|
||
ELEMENT title
|
||
TEXT
|
||
content=Welcome to Gnome
|
||
ELEMENT chapter
|
||
ELEMENT title
|
||
TEXT
|
||
content=The Linux adventure
|
||
ELEMENT p
|
||
TEXT
|
||
content=bla bla bla ...
|
||
ELEMENT image
|
||
ATTRIBUTE href
|
||
TEXT
|
||
content=linus.gif
|
||
ELEMENT p
|
||
TEXT
|
||
content=...</pre>
|
||
|
||
<p>This should be useful for learning the internal representation model.</p>
|
||
|
||
<h2><a name="interface">The SAX interface</a></h2>
|
||
|
||
<p>Sometimes the DOM tree output is just too large to fit reasonably into
|
||
memory. In that case (and if you don't expect to save back the XML document
|
||
loaded using libxml), it's better to use the SAX interface of libxml. SAX is
|
||
a <strong>callback-based interface</strong> to the parser. Before parsing,
|
||
the application layer registers a customized set of callbacks which are
|
||
called by the library as it progresses through the XML input.</p>
|
||
|
||
<p>To get more detailed step-by-step guidance on using the SAX interface of
|
||
libxml, see the <a
|
||
href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
|
||
documentation</a>.written by <a href="mailto:james@daa.com.au">James
|
||
Henstridge</a>.</p>
|
||
|
||
<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
|
||
program located in the gnome-xml module (it's usually not shipped in the
|
||
binary packages of libxml, but you can find it in the tar source
|
||
distribution). Here is the sequence of callbacks that would be reported by
|
||
testSAX when parsing the example XML document shown earlier:</p>
|
||
<pre>SAX.setDocumentLocator()
|
||
SAX.startDocument()
|
||
SAX.getEntity(amp)
|
||
SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too')
|
||
SAX.characters( , 3)
|
||
SAX.startElement(head)
|
||
SAX.characters( , 4)
|
||
SAX.startElement(title)
|
||
SAX.characters(Welcome to Gnome, 16)
|
||
SAX.endElement(title)
|
||
SAX.characters( , 3)
|
||
SAX.endElement(head)
|
||
SAX.characters( , 3)
|
||
SAX.startElement(chapter)
|
||
SAX.characters( , 4)
|
||
SAX.startElement(title)
|
||
SAX.characters(The Linux adventure, 19)
|
||
SAX.endElement(title)
|
||
SAX.characters( , 4)
|
||
SAX.startElement(p)
|
||
SAX.characters(bla bla bla ..., 15)
|
||
SAX.endElement(p)
|
||
SAX.characters( , 4)
|
||
SAX.startElement(image, href='linus.gif')
|
||
SAX.endElement(image)
|
||
SAX.characters( , 4)
|
||
SAX.startElement(p)
|
||
SAX.characters(..., 3)
|
||
SAX.endElement(p)
|
||
SAX.characters( , 3)
|
||
SAX.endElement(chapter)
|
||
SAX.characters( , 1)
|
||
SAX.endElement(EXAMPLE)
|
||
SAX.endDocument()</pre>
|
||
|
||
<p>Most of the other interfaces of libxml are based on the DOM tree-building
|
||
facility, so nearly everything up to the end of this document presupposes the
|
||
use of the standard DOM tree build. Note that the DOM tree itself is built by
|
||
a set of registered default callbacks, without internal specific
|
||
interface.</p>
|
||
|
||
<h2><a name="library">The XML library interfaces</a></h2>
|
||
|
||
<p>This section is directly intended to help programmers getting bootstrapped
|
||
using the XML library from the C language. It is not intended to be
|
||
extensive. I hope the automatically generated documents will provide the
|
||
completeness required, but as a separate set of documents. The interfaces of
|
||
the XML library are by principle low level, there is nearly zero abstraction.
|
||
Those interested in a higher level API should <a href="#DOM">look at
|
||
DOM</a>.</p>
|
||
|
||
<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
|
||
separated from the <a href="html/libxml-htmlparser.html">HTML parser
|
||
interfaces</a>. Let's have a look at how the XML parser can be called:</p>
|
||
|
||
<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
|
||
|
||
<p>Usually, the first thing to do is to read an XML input. The parser accepts
|
||
documents either from in-memory strings or from files. The functions are
|
||
defined in "parser.h":</p>
|
||
<dl>
|
||
<dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
|
||
<dd><p>Parse a null-terminated string containing the document.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
|
||
<dd><p>Parse an XML document contained in a (possibly compressed)
|
||
file.</p>
|
||
</dd>
|
||
</dl>
|
||
|
||
<p>The parser returns a pointer to the document structure (or NULL in case of
|
||
failure).</p>
|
||
|
||
<h3 id="Invoking1">Invoking the parser: the push method</h3>
|
||
|
||
<p>In order for the application to keep the control when the document is
|
||
being fetched (which is common for GUI based programs) libxml provides a push
|
||
interface, too, as of version 1.8.3. Here are the interface functions:</p>
|
||
<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
|
||
void *user_data,
|
||
const char *chunk,
|
||
int size,
|
||
const char *filename);
|
||
int xmlParseChunk (xmlParserCtxtPtr ctxt,
|
||
const char *chunk,
|
||
int size,
|
||
int terminate);</pre>
|
||
|
||
<p>and here is a simple example showing how to use the interface:</p>
|
||
<pre> FILE *f;
|
||
|
||
f = fopen(filename, "r");
|
||
if (f != NULL) {
|
||
int res, size = 1024;
|
||
char chars[1024];
|
||
xmlParserCtxtPtr ctxt;
|
||
|
||
res = fread(chars, 1, 4, f);
|
||
if (res > 0) {
|
||
ctxt = xmlCreatePushParserCtxt(NULL, NULL,
|
||
chars, res, filename);
|
||
while ((res = fread(chars, 1, size, f)) > 0) {
|
||
xmlParseChunk(ctxt, chars, res, 0);
|
||
}
|
||
xmlParseChunk(ctxt, chars, 0, 1);
|
||
doc = ctxt->myDoc;
|
||
xmlFreeParserCtxt(ctxt);
|
||
}
|
||
}</pre>
|
||
|
||
<p>The HTML parser embedded into libxml also has a push interface; the
|
||
functions are just prefixed by "html" rather than "xml".</p>
|
||
|
||
<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
|
||
|
||
<p>The tree-building interface makes the parser memory-hungry, first loading
|
||
the document in memory and then building the tree itself. Reading a document
|
||
without building the tree is possible using the SAX interfaces (see SAX.h and
|
||
<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
|
||
Henstridge's documentation</a>). Note also that the push interface can be
|
||
limited to SAX: just use the two first arguments of
|
||
<code>xmlCreatePushParserCtxt()</code>.</p>
|
||
|
||
<h3><a name="Building">Building a tree from scratch</a></h3>
|
||
|
||
<p>The other way to get an XML tree in memory is by building it. Basically
|
||
there is a set of functions dedicated to building new elements. (These are
|
||
also described in <libxml/tree.h>.) For example, here is a piece of
|
||
code that produces the XML document used in the previous examples:</p>
|
||
<pre> #include <libxml/tree.h>
|
||
xmlDocPtr doc;
|
||
xmlNodePtr tree, subtree;
|
||
|
||
doc = xmlNewDoc("1.0");
|
||
doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
|
||
xmlSetProp(doc->children, "prop1", "gnome is great");
|
||
xmlSetProp(doc->children, "prop2", "& linux too");
|
||
tree = xmlNewChild(doc->children, NULL, "head", NULL);
|
||
subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
|
||
tree = xmlNewChild(doc->children, NULL, "chapter", NULL);
|
||
subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
|
||
subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
|
||
subtree = xmlNewChild(tree, NULL, "image", NULL);
|
||
xmlSetProp(subtree, "href", "linus.gif");</pre>
|
||
|
||
<p>Not really rocket science ...</p>
|
||
|
||
<h3><a name="Traversing">Traversing the tree</a></h3>
|
||
|
||
<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
|
||
code has access to the internal structure of all the elements of the tree.
|
||
The names should be somewhat simple like <strong>parent</strong>,
|
||
<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
|
||
<strong>properties</strong>, etc... For example, still with the previous
|
||
example:</p>
|
||
<pre><code>doc->children->children->children</code></pre>
|
||
|
||
<p>points to the title element,</p>
|
||
<pre>doc->children->children->next->children->children</pre>
|
||
|
||
<p>points to the text node containing the chapter title "The Linux
|
||
adventure".</p>
|
||
|
||
<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
|
||
present before the document root, so <code>doc->children</code> may point
|
||
to an element which is not the document Root Element; a function
|
||
<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
|
||
|
||
<h3><a name="Modifying">Modifying the tree</a></h3>
|
||
|
||
<p>Functions are provided for reading and writing the document content. Here
|
||
is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
|
||
<dl>
|
||
<dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
|
||
xmlChar *value);</code></dt>
|
||
<dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
|
||
The value can be NULL.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
|
||
*name);</code></dt>
|
||
<dd><p>This function returns a pointer to new copy of the property
|
||
content. Note that the user must deallocate the result.</p>
|
||
</dd>
|
||
</dl>
|
||
|
||
<p>Two functions are provided for reading and writing the text associated
|
||
with elements:</p>
|
||
<dl>
|
||
<dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
|
||
*value);</code></dt>
|
||
<dd><p>This function takes an "external" string and converts it to one
|
||
text node or possibly to a list of entity and text nodes. All
|
||
non-predefined entity references like &Gnome; will be stored
|
||
internally as entity nodes, hence the result of the function may not be
|
||
a single node.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
|
||
inLine);</code></dt>
|
||
<dd><p>This function is the inverse of
|
||
<code>xmlStringGetNodeList()</code>. It generates a new string
|
||
containing the content of the text and entity nodes. Note the extra
|
||
argument inLine. If this argument is set to 1, the function will expand
|
||
entity references. For example, instead of returning the &Gnome;
|
||
XML encoding in the string, it will substitute it with its value (say,
|
||
"GNU Network Object Model Environment").</p>
|
||
</dd>
|
||
</dl>
|
||
|
||
<h3><a name="Saving">Saving a tree</a></h3>
|
||
|
||
<p>Basically 3 options are possible:</p>
|
||
<dl>
|
||
<dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
|
||
*size);</code></dt>
|
||
<dd><p>Returns a buffer into which the document has been saved.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
|
||
<dd><p>Dumps a document to an open file descriptor.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
|
||
<dd><p>Saves the document to a file. In this case, the compression
|
||
interface is triggered if it has been turned on.</p>
|
||
</dd>
|
||
</dl>
|
||
|
||
<h3><a name="Compressio">Compression</a></h3>
|
||
|
||
<p>The library transparently handles compression when doing file-based
|
||
accesses. The level of compression on saves can be turned on either globally
|
||
or individually for one file:</p>
|
||
<dl>
|
||
<dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
|
||
<dd><p>Gets the document compression ratio (0-9).</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
|
||
<dd><p>Sets the document compression ratio.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>int xmlGetCompressMode(void);</code></dt>
|
||
<dd><p>Gets the default compression ratio.</p>
|
||
</dd>
|
||
</dl>
|
||
<dl>
|
||
<dt><code>void xmlSetCompressMode(int mode);</code></dt>
|
||
<dd><p>Sets the default compression ratio.</p>
|
||
</dd>
|
||
</dl>
|
||
|
||
<h2><a name="Entities">Entities or no entities</a></h2>
|
||
|
||
<p>Entities in principle are similar to simple C macros. An entity defines an
|
||
abbreviation for a given string that you can reuse many times throughout the
|
||
content of your document. Entities are especially useful when a given string
|
||
may occur frequently within a document, or to confine the change needed to a
|
||
document to a restricted area in the internal subset of the document (at the
|
||
beginning). Example:</p>
|
||
<pre>1 <?xml version="1.0"?>
|
||
2 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
|
||
3 <!ENTITY xml "Extensible Markup Language">
|
||
4 ]>
|
||
5 <EXAMPLE>
|
||
6 &xml;
|
||
7 </EXAMPLE></pre>
|
||
|
||
<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
|
||
its name with '&' and following it by ';' without any spaces added. There
|
||
are 5 predefined entities in libxml allowing you to escape charaters with
|
||
predefined meaning in some parts of the xml document content:
|
||
<strong>&lt;</strong> for the character '<', <strong>&gt;</strong>
|
||
for the character '>', <strong>&apos;</strong> for the character ''',
|
||
<strong>&quot;</strong> for the character '"', and
|
||
<strong>&amp;</strong> for the character '&'.</p>
|
||
|
||
<p>One of the problems related to entities is that you may want the parser to
|
||
substitute an entity's content so that you can see the replacement text in
|
||
your application. Or you may prefer to keep entity references as such in the
|
||
content to be able to save the document back without losing this usually
|
||
precious information (if the user went through the pain of explicitly
|
||
defining entities, he may have a a rather negative attitude if you blindly
|
||
susbtitute them as saving time). The <a
|
||
href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
|
||
function allows you to check and change the behaviour, which is to not
|
||
substitute entities by default.</p>
|
||
|
||
<p>Here is the DOM tree built by libxml for the previous document in the
|
||
default case:</p>
|
||
<pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1
|
||
DOCUMENT
|
||
version=1.0
|
||
ELEMENT EXAMPLE
|
||
TEXT
|
||
content=
|
||
ENTITY_REF
|
||
INTERNAL_GENERAL_ENTITY xml
|
||
content=Extensible Markup Language
|
||
TEXT
|
||
content=</pre>
|
||
|
||
<p>And here is the result when substituting entities:</p>
|
||
<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
|
||
DOCUMENT
|
||
version=1.0
|
||
ELEMENT EXAMPLE
|
||
TEXT
|
||
content= Extensible Markup Language</pre>
|
||
|
||
<p>So, entities or no entities? Basically, it depends on your use case. I
|
||
suggest that you keep the non-substituting default behaviour and avoid using
|
||
entities in your XML document or data if you are not willing to handle the
|
||
entity references elements in the DOM tree.</p>
|
||
|
||
<p>Note that at save time libxml enforces the conversion of the predefined
|
||
entities where necessary to prevent well-formedness problems, and will also
|
||
transparently replace those with chars (i.e. it will not generate entity
|
||
reference elements in the DOM tree or call the reference() SAX callback when
|
||
finding them in the input).</p>
|
||
|
||
<p><span style="background-color: #FF0000">WARNING</span>: handling entities
|
||
on top of the libxml SAX interface is difficult!!! If you plan to use
|
||
non-predefined entities in your documents, then the learning cuvre to handle
|
||
then using the SAX API may be long. If you plan to use complex documents, I
|
||
strongly suggest you consider using the DOM interface instead and let libxml
|
||
deal with the complexity rather than trying to do it yourself.</p>
|
||
|
||
<h2><a name="Namespaces">Namespaces</a></h2>
|
||
|
||
<p>The libxml library implements <a
|
||
href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
|
||
recognizing namespace contructs in the input, and does namespace lookup
|
||
automatically when building the DOM tree. A namespace declaration is
|
||
associated with an in-memory structure and all elements or attributes within
|
||
that namespace point to it. Hence testing the namespace is a simple and fast
|
||
equality operation at the user level.</p>
|
||
|
||
<p>I suggest that people using libxml use a namespace, and declare it in the
|
||
root element of their document as the default namespace. Then they don't need
|
||
to use the prefix in the content but we will have a basis for future semantic
|
||
refinement and merging of data from different sources. This doesn't increase
|
||
the size of the XML output significantly, but significantly increases its
|
||
value in the long-term. Example:</p>
|
||
<pre><mydoc xmlns="http://mydoc.example.org/schemas/">
|
||
<elem1>...</elem1>
|
||
<elem2>...</elem2>
|
||
</mydoc></pre>
|
||
|
||
<p>The namespace value has to be an absolute URL, but the URL doesn't have to
|
||
point to any existing resource on the Web. It will bind all the element and
|
||
atributes with that URL. I suggest to use an URL within a domain you control,
|
||
and that the URL should contain some kind of version information if possible.
|
||
For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
|
||
namespace scheme.</p>
|
||
|
||
<p>Then when you load a file, make sure that a namespace carrying the
|
||
version-independent prefix is installed on the root element of your document,
|
||
and if the version information don't match something you know, warn the user
|
||
and be liberal in what you accept as the input. Also do *not* try to base
|
||
namespace checking on the prefix value. <foo:text> may be exactly the
|
||
same as <bar:text> in another document. What really matters is the URI
|
||
associated with the element or the attribute, not the prefix string (which is
|
||
just a shortcut for the full URI). In libxml, element and attributes have an
|
||
<code>ns</code> field pointing to an xmlNs structure detailing the namespace
|
||
prefix and its URI.</p>
|
||
|
||
<p>@@Interfaces@@</p>
|
||
|
||
<p>@@Examples@@</p>
|
||
|
||
<p>Usually people object to using namespaces together with validity checking.
|
||
I will try to make sure that using namespaces won't break validity checking,
|
||
so even if you plan to use or currently are using validation I strongly
|
||
suggest adding namespaces to your document. A default namespace scheme
|
||
<code>xmlns="http://...."</code> should not break validity even on less
|
||
flexible parsers. Using namespaces to mix and differentiate content coming
|
||
from multiple DTDs will certainly break current validation schemes. I will
|
||
try to provide ways to do this, but this may not be portable or
|
||
standardized.</p>
|
||
|
||
<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
|
||
|
||
<p>Well what is validation and what is a DTD ?</p>
|
||
|
||
<p>Validation is the process of checking a document against a set of
|
||
construction rules; a <strong>DTD</strong> (Document Type Definition) is such
|
||
a set of rules.</p>
|
||
|
||
<p>The validation process and building DTDs are the two most difficult parts
|
||
of the XML life cycle. Briefly a DTD defines all the possibles element to be
|
||
found within your document, what is the formal shape of your document tree
|
||
(by defining the allowed content of an element, either text, a regular
|
||
expression for the allowed list of children, or mixed content i.e. both text
|
||
and children). The DTD also defines the allowed attributes for all elements
|
||
and the types of the attributes. For more detailed information, I suggest
|
||
that you read the related parts of the XML specification, the examples found
|
||
under gnome-xml/test/valid/dtd and any of the large number of books available
|
||
on XML. The dia example in gnome-xml/test/valid should be both simple and
|
||
complete enough to allow you to build your own.</p>
|
||
|
||
<p>A word of warning, building a good DTD which will fit the needs of your
|
||
application in the long-term is far from trivial; however, the extra level of
|
||
quality it can ensure is well worth the price for some sets of applications
|
||
or if you already have already a DTD defined for your application field.</p>
|
||
|
||
<p>The validation is not completely finished but in a (very IMHO) usable
|
||
state. Until a real validation interface is defined the way to do it is to
|
||
define and set the <strong>xmlDoValidityCheckingDefaultValue</strong>
|
||
external variable to 1, this will of course be changed at some point:</p>
|
||
|
||
<p>extern int xmlDoValidityCheckingDefaultValue;</p>
|
||
|
||
<p>...</p>
|
||
|
||
<p>xmlDoValidityCheckingDefaultValue = 1;</p>
|
||
|
||
<p></p>
|
||
|
||
<p>To handle external entities, use the function
|
||
<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
|
||
link in you HTTP/FTP/Entities database library to the standard libxml
|
||
core.</p>
|
||
|
||
<p>@@interfaces@@</p>
|
||
|
||
<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
|
||
|
||
<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
|
||
Object Model</em>; this is an API for accessing XML or HTML structured
|
||
documents. Native support for DOM in Gnome is on the way (module gnome-dom),
|
||
and will be based on gnome-xml. This will be a far cleaner interface to
|
||
manipulate XML files within Gnome since it won't expose the internal
|
||
structure.</p>
|
||
|
||
<p>The current DOM implementation on top of libxml is the <a
|
||
href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
|
||
is a full DOM interface, thanks to Paolo Casarini, check the <a
|
||
href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
|
||
informations.</p>
|
||
|
||
<h2><a name="Example"></a><a name="real">A real example</a></h2>
|
||
|
||
<p>Here is a real size example, where the actual content of the application
|
||
data is not kept in the DOM tree but uses internal structures. It is based on
|
||
a proposal to keep a database of jobs related to Gnome, with an XML based
|
||
storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
|
||
base</a>:</p>
|
||
<pre><?xml version="1.0"?>
|
||
<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
|
||
<gjob:Jobs>
|
||
|
||
<gjob:Job>
|
||
<gjob:Project ID="3"/>
|
||
<gjob:Application>GBackup</gjob:Application>
|
||
<gjob:Category>Development</gjob:Category>
|
||
|
||
<gjob:Update>
|
||
<gjob:Status>Open</gjob:Status>
|
||
<gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified>
|
||
<gjob:Salary>USD 0.00</gjob:Salary>
|
||
</gjob:Update>
|
||
|
||
<gjob:Developers>
|
||
<gjob:Developer>
|
||
</gjob:Developer>
|
||
</gjob:Developers>
|
||
|
||
<gjob:Contact>
|
||
<gjob:Person>Nathan Clemons</gjob:Person>
|
||
<gjob:Email>nathan@windsofstorm.net</gjob:Email>
|
||
<gjob:Company>
|
||
</gjob:Company>
|
||
<gjob:Organisation>
|
||
</gjob:Organisation>
|
||
<gjob:Webpage>
|
||
</gjob:Webpage>
|
||
<gjob:Snailmail>
|
||
</gjob:Snailmail>
|
||
<gjob:Phone>
|
||
</gjob:Phone>
|
||
</gjob:Contact>
|
||
|
||
<gjob:Requirements>
|
||
The program should be released as free software, under the GPL.
|
||
</gjob:Requirements>
|
||
|
||
<gjob:Skills>
|
||
</gjob:Skills>
|
||
|
||
<gjob:Details>
|
||
A GNOME based system that will allow a superuser to configure
|
||
compressed and uncompressed files and/or file systems to be backed
|
||
up with a supported media in the system. This should be able to
|
||
perform via find commands generating a list of files that are passed
|
||
to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
|
||
or via operations performed on the filesystem itself. Email
|
||
notification and GUI status display very important.
|
||
</gjob:Details>
|
||
|
||
</gjob:Job>
|
||
|
||
</gjob:Jobs>
|
||
</gjob:Helping></pre>
|
||
|
||
<p>While loading the XML file into an internal DOM tree is a matter of
|
||
calling only a couple of functions, browsing the tree to gather the ata and
|
||
generate the internal structures is harder, and more error prone.</p>
|
||
|
||
<p>The suggested principle is to be tolerant with respect to the input
|
||
structure. For example, the ordering of the attributes is not significant,
|
||
the XML specification is clear about it. It's also usually a good idea not to
|
||
depend on the order of the children of a given node, unless it really makes
|
||
things harder. Here is some code to parse the information for a person:</p>
|
||
<pre>/*
|
||
* A person record
|
||
*/
|
||
typedef struct person {
|
||
char *name;
|
||
char *email;
|
||
char *company;
|
||
char *organisation;
|
||
char *smail;
|
||
char *webPage;
|
||
char *phone;
|
||
} person, *personPtr;
|
||
|
||
/*
|
||
* And the code needed to parse it
|
||
*/
|
||
personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
|
||
personPtr ret = NULL;
|
||
|
||
DEBUG("parsePerson\n");
|
||
/*
|
||
* allocate the struct
|
||
*/
|
||
ret = (personPtr) malloc(sizeof(person));
|
||
if (ret == NULL) {
|
||
fprintf(stderr,"out of memory\n");
|
||
return(NULL);
|
||
}
|
||
memset(ret, 0, sizeof(person));
|
||
|
||
/* We don't care what the top level element name is */
|
||
cur = cur->xmlChildrenNode;
|
||
while (cur != NULL) {
|
||
if ((!strcmp(cur->name, "Person")) && (cur->ns == ns))
|
||
ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
|
||
if ((!strcmp(cur->name, "Email")) && (cur->ns == ns))
|
||
ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
|
||
cur = cur->next;
|
||
}
|
||
|
||
return(ret);
|
||
}</pre>
|
||
|
||
<p>Here are a couple of things to notice:</p>
|
||
<ul>
|
||
<li>Usually a recursive parsing style is the more convenient one: XML data
|
||
is by nature subject to repetitive constructs and usually exibits highly
|
||
stuctured patterns.</li>
|
||
<li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
|
||
i.e. the pointer to the global XML document and the namespace reserved to
|
||
the application. Document wide information are needed for example to
|
||
decode entities and it's a good coding practice to define a namespace for
|
||
your application set of data and test that the element and attributes
|
||
you're analyzing actually pertains to your application space. This is
|
||
done by a simple equality test (cur->ns == ns).</li>
|
||
<li>To retrieve text and attributes value, you can use the function
|
||
<em>xmlNodeListGetString</em> to gather all the text and entity reference
|
||
nodes generated by the DOM output and produce an single text string.</li>
|
||
</ul>
|
||
|
||
<p>Here is another piece of code used to parse another level of the
|
||
structure:</p>
|
||
<pre>#include <libxml/tree.h>
|
||
/*
|
||
* a Description for a Job
|
||
*/
|
||
typedef struct job {
|
||
char *projectID;
|
||
char *application;
|
||
char *category;
|
||
personPtr contact;
|
||
int nbDevelopers;
|
||
personPtr developers[100]; /* using dynamic alloc is left as an exercise */
|
||
} job, *jobPtr;
|
||
|
||
/*
|
||
* And the code needed to parse it
|
||
*/
|
||
jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
|
||
jobPtr ret = NULL;
|
||
|
||
DEBUG("parseJob\n");
|
||
/*
|
||
* allocate the struct
|
||
*/
|
||
ret = (jobPtr) malloc(sizeof(job));
|
||
if (ret == NULL) {
|
||
fprintf(stderr,"out of memory\n");
|
||
return(NULL);
|
||
}
|
||
memset(ret, 0, sizeof(job));
|
||
|
||
/* We don't care what the top level element name is */
|
||
cur = cur->xmlChildrenNode;
|
||
while (cur != NULL) {
|
||
|
||
if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) {
|
||
ret->projectID = xmlGetProp(cur, "ID");
|
||
if (ret->projectID == NULL) {
|
||
fprintf(stderr, "Project has no ID\n");
|
||
}
|
||
}
|
||
if ((!strcmp(cur->name, "Application")) && (cur->ns == ns))
|
||
ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
|
||
if ((!strcmp(cur->name, "Category")) && (cur->ns == ns))
|
||
ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
|
||
if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns))
|
||
ret->contact = parsePerson(doc, ns, cur);
|
||
cur = cur->next;
|
||
}
|
||
|
||
return(ret);
|
||
}</pre>
|
||
|
||
<p>Once you are used to it, writing this kind of code is quite simple, but
|
||
boring. Ultimately, it could be possble to write stubbers taking either C
|
||
data structure definitions, a set of XML examples or an XML DTD and produce
|
||
the code needed to import and export the content between C data and XML
|
||
storage. This is left as an exercise to the reader :-)</p>
|
||
|
||
<p>Feel free to use <a href="example/gjobread.c">the code for the full C
|
||
parsing example</a> as a template, it is also available with Makefile in the
|
||
Gnome CVS base under gnome-xml/example</p>
|
||
|
||
<h2><a name="Contributi">Contributions</a></h2>
|
||
<ul>
|
||
<li><a href="mailto:ari@lusis.org">Ari Johnson</a>
|
||
provides a C++ wrapper for libxml:
|
||
<p>Website: <a
|
||
href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
|
||
<p>Download: <a
|
||
href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
|
||
</li>
|
||
<li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
|
||
is now the maintainer of the Windows port, <a
|
||
href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
|
||
provides binaries</a></li>
|
||
<li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
|
||
provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
|
||
binaries</a></li>
|
||
<li><a
|
||
href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
|
||
Sergeant</a>
|
||
developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
|
||
wrapper for libxml2/libxslt as part of the <a
|
||
href="http://axkit.com/">AxKit XML application server</a></li>
|
||
<li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
|
||
and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
|
||
href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
|
||
documentation</li>
|
||
<li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
|
||
provided <a href="http://xmlsoft.org/messages/0488.html">man
|
||
pages</a></li>
|
||
<li>there is a module for <a
|
||
href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
|
||
in OpenNSD/AOLServer</a></li>
|
||
<li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
|
||
provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
|
||
for Python</a></li>
|
||
</ul>
|
||
|
||
<p></p>
|
||
|
||
<p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
|
||
|
||
<p>$Id: xml.html,v 1.113 2001/10/19 14:50:57 veillard Exp $</p>
|
||
</body>
|
||
</html>
|