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4<head>
5 <title>Libxml Frequently asqued Questions</title>
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11<h1 align="center">Libxml Frequently Asqued Questions</h1>
12
13<p>Location: <a
14href="http://xmlsoft.org/FAQ.html">http://xmlsoft.org/FAQ.html</a></p>
15
16<p>Libxml home page: <a href="http://xmlsoft.org/">http://xmlsoft.org/</a></p>
17
18<p>Mailing-list archive: <a
19href="http://xmlsoft.org/messages/">http://xmlsoft.org/messages/</a></p>
20
Daniel Veillardbe40c8b2000-07-14 12:10:59 +0000[diff] [blame]21<p>Version: $Revision$</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]22
23<p>Table of Content:</p>
24<ul>
25 <li><a href="#Licence">Licence(s)</a></li>
26 <li><a href="#Installati">Installation</a></li>
27 <li><a href="#Compilatio">Compilation</a></li>
28 <li><a href="#Developper">Developper corner</a></li>
29</ul>
30
31<h2><a name="Licence">Licence</a>(s)</h2>
32<ol>
33 <li><em>Licensing Terms for libxml</em>
34 <p>libxml is released under 2 (compatible) licences:</p>
35 <ul>
36 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
37 Library General Public License</li>
38 <li>the <a
39 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
40 IPR</a>: very similar to the XWindow licence</li>
41 </ul>
42 </li>
43 <li><em>Can I embed libxml in a proprietary application ?</em>
44 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
45 made to libxml, but it would be graceful to provide back bugfixes and
46 improvements as patches for possible incorporation in the main
47 developement tree</p>
48 </li>
49</ol>
50
51<h2><a name="Installati">Installation</a></h2>
52<ol>
53 <li><em>Where can I get libxml</em> ?
54 <p>The original distribution comes from <a
55 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
56 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
57 <p>Most linux and Bsd distribution includes libxml, this is probably the
58 safer way for end-users</p>
59 <p>David Doolin provides precompiled Windows versions at <a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]60 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]61 </li>
62 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
63 <ul>
64 <li>If you are not concerned by any existing backward compatibility with
65 existing application, install libxml2 only</li>
66 <li>If you are not doing development, you can safely install both.
67 usually the packages <a
68 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
69 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
70 compatible (this is not the case for development packages)</li>
71 <li>If you are a developper and your system provides separate packaging
72 for shared libraries and the development components, it is possible to
73 install libxml and libxml2, and depending on your development needs
74 have either <a
75 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
76 or <a
77 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
78 too</li>
79 <li>If you are developping a new application, please develop against
80 libxml2(-devel)</li>
81 </ul>
82 </li>
83 <li><em>I can't install the libxml package it conflicts with libxml0</em>
84 <p>You probably have an old libxml0 package used to provide the shared
85 library for libxml.so.0, you can probably safely remove it. Anyway the
86 libxml packages provided on <a
87 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
88 libxml.so.0</p>
89 </li>
90</ol>
91
92<h2><a name="Compilatio">Compilation</a></h2>
93<ol>
94 <li><em>What is the process to compile libxml ?</em>
95 <p>As most UNIX libraries libxml follows the "standard":</p>
96 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
97 <p><code>cd libxml-xxxx</code></p>
98 <p><code>./configure --help</code></p>
99 <p>to see the options, then the compilation/installation proper</p>
100 <p><code>./configure [possible options]</code></p>
101 <p><code>make</code></p>
102 <p><code>make install</code></p>
103 <p>At that point you may have to rerun ldconfig or similar utility to
104 update your list of installed shared libs.</p>
105 </li>
106 <li><em>What other libraries are needed to compile/install libxml ?</em>
107 <p>Libxml does not requires any other library, the normal C ANSI API
108 should be sufficient (please report any violation to this rule you may
109 find).</p>
110 <p>However if found at configuration time libxml will deect and use the
111 following libs:</p>
112 <ul>
113 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>: a
114 highly portable and available widely compression library</li>
115 <li>iconv: a powerful character encoding conversion library. It's
116 included by default on recent glibc libraries, so it doesn't need to
117 be installed specifically on linux. It seems it's now <a
118 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part of
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]119 the official UNIX</a> specification. Here is one <a
120 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
121 of the library</a> which source can be found <a
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]122 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]123 </ul>
124 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]125 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
126 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
127 CFLAGS</p>
128 <p>you can also install and use gcc instead or use a precompiled version
129 of libxml, both available from the <a
130 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
131 and Archive Centre</a></p>
132 </li>
133 <li><em>make check fails on some platforms</em>
134 <p>Sometime the regression tests results don't completely match the value
135 produced by the parser, and the makefile uses diff to print the delta. On
136 some platforms the diff return breaks the compilation process, if the diff
137 is small this is probably not a serious problem</p>
138 </li>
139</ol>
140
141<h2><a name="Developper">Developper</a> corner</h2>
142<ol>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]143 <li>Extra nodes in the document:
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame^]144 <p><em>For a XML file as below:</em></p>
145 <pre>&lt;?xml version="1.0"?&gt;
146&lt;PLAN
147xmlns="http://www.argus.ca/autotest/1.0/"&gt;
148&lt;NODE CommFlag="0"/&gt;
149&lt;NODE CommFlag="1"/&gt;
150&lt;/PLAN&gt;</pre>
151 <p><em>after parsing it with the function pxmlDoc=xmlParseFile(...);</em></p>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]152 <p><em>I want to the get the content of the first node (node with the
153 CommFlag="0")</em></p>
154 <p><em>so I did it as following;</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame^]155 <pre>xmlNodePtr pode;
156pnode=pxmlDoc-&gt;children-&gt;children;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]157 <p><em>but it does not work. If I change it to</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame^]158 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]159 <p><em>then it works. Can someone explain it to me.</em></p>
160 <p></p>
161 <p>In XML all characters in the content of the document are signifficant
162 <strong>including blanks and formatting line breaks</strong>.</p>
163 <p>The extra nodes you are wondering about are just that, text nodes with
164 the formatting spaces wich are part of the document but that people tend
165 to forget. There is a function <a
166 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
167 ()</a> to remove those at parse time, but that's an heuristic, and its
168 use should be limited to case where you are sure there is no mixed-content
169 in the document.</p>
170 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]171 <li><em>I get compilation errors of existing code like when accessing
172 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
173 <p>You are compiling code developped for libxml version 1 and using a
174 libxml2 developement environment. Either switch back to libxml v1 devel or
175 even better fix the code to compile with libxml2 (or both) by <a
176 href="upgrade.html">following the instructions</a>.</p>
177 </li>
178 <li><em>I get compilation errors about non existing
179 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
180 fields</em>
181 <p>The source code you are using has been <a
182 href="upgrade.html">upgraded</a> to be able to compile with both libxml
183 and libxml2, but you need to install a more recent version: libxml(-devel)
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]184 &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]185 </li>
186 <li><em>XPath implementation looks seriously broken</em>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]187 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to a
188 recent version, the implementation and debug of libxslt generated fixes
189 for most obvious problems. </p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]190 </li>
191 <li><em>The example provided in the web page does not compile</em>
192 <p>It's hard to maintain the documentation in sync with the code
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]193 &lt;grin/&gt; ...</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]194 <p>Check the previous points 1/ and 2/ raised before, and send
195 patches.</p>
196 </li>
197 <li><em>Where can I get more examples and informations than in the web
198 page</em>
199 <p>Ideally a libxml book would be nice. I have no such plan ... But you
200 can:</p>
201 <ul>
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]202 <li>check more deeply the <a href="html/libxml-lib.html">existing
203 generated doc</a></li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]204 <li>looks for examples of use for libxml function using the Gnome code
205 for example the following will query the full Gnome CVs base for the
206 use of the <strong>xmlAddChild()</strong> function:
207 <p><a
208 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
209 <p>This may be slow, a large hardware donation to the gnome project
210 could cure this :-)</p>
211 </li>
212 <li><a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]213 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]214 the libxml source</a>, I try to write code as clean and documented as
215 possible, so looking at it may be helpful</li>
216 </ul>
217 </li>
218 <li>What about C++ ?
219 <p>libxml is written in pure C in order to allow easy reuse on a number of
220 platforms, including embedded systems. I don't intend to convert to
221 C++.</p>
222 <p>There is however a C++ wrapper provided by Ari Johnson
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]223 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]224 <p>Website: <a
225 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
226 <p>Download: <a
227 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
228 </li>
229 <li>How to validate a document a posteriori ?
230 <p>It is possible to validate documents which had not been validated at
231 initial parsing time or documents who have been built from scratch using
232 the API. Use the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]233 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]234 function. It is also possible to simply add a Dtd to an existing
235 document:</p>
236 <pre>xmlDocPtr doc; /* your existing document */
237 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]238 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]239
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]240 doc-&gt;intSubset = dtd;
241 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
242 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]243 </pre>
244 </li>
245 <li>etc ...</li>
246</ol>
247
248<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
249
250<p>$Id$</p>
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