1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css"> 4TD {font-family: Verdana,Arial,Helvetica} 5BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em} 6H1 {font-family: Verdana,Arial,Helvetica} 7H2 {font-family: Verdana,Arial,Helvetica} 8H3 {font-family: Verdana,Arial,Helvetica} 9A:link, A:visited, A:active { text-decoration: underline } 10</style><title>FAQ</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td 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border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>Table of Contents:</p><ul><li><a href="FAQ.html#License">License(s)</a></li> 11 <li><a href="FAQ.html#Installati">Installation</a></li> 12 <li><a href="FAQ.html#Compilatio">Compilation</a></li> 13 <li><a href="FAQ.html#Developer">Developer corner</a></li> 14</ul><h3><a name="License" id="License">License</a>(s)</h3><ol><li><em>Licensing Terms for libxml</em> 15 <p>libxml2 is released under the <a href="http://www.opensource.org/licenses/mit-license.html">MIT 16 License</a>; see the file Copyright in the distribution for the precise 17 wording</p> 18 </li> 19 <li><em>Can I embed libxml2 in a proprietary application ?</em> 20 <p>Yes. The MIT License allows you to keep proprietary the changes you 21 made to libxml, but it would be graceful to send-back bug fixes and 22 improvements as patches for possible incorporation in the main 23 development tree.</p> 24 </li> 25</ol><h3><a name="Installati" id="Installati">Installation</a></h3><ol><li><strong><span style="background-color: #FF0000">Do Not Use 26 libxml1</span></strong>, use libxml2</li> 27 <p></p> 28 <li><em>Where can I get libxml</em> ? 29 <p>The original distribution comes from <a href="ftp://xmlsoft.org/libxml2/">xmlsoft.org</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">gnome.org</a></p> 30 <p>Most Linux and BSD distributions include libxml, this is probably the 31 safer way for end-users to use libxml.</p> 32 <p>David Doolin provides precompiled Windows versions at <a href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p> 33 </li> 34 <p></p> 35 <li><em>I see libxml and libxml2 releases, which one should I install ?</em> 36 <ul><li>If you are not constrained by backward compatibility issues with 37 existing applications, install libxml2 only</li> 38 <li>If you are not doing development, you can safely install both. 39 Usually the packages <a href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are 40 compatible (this is not the case for development packages).</li> 41 <li>If you are a developer and your system provides separate packaging 42 for shared libraries and the development components, it is possible 43 to install libxml and libxml2, and also <a href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a> 44 and <a href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a> 45 too for libxml2 >= 2.3.0</li> 46 <li>If you are developing a new application, please develop against 47 libxml2(-devel)</li> 48 </ul></li> 49 <li><em>I can't install the libxml package, it conflicts with libxml0</em> 50 <p>You probably have an old libxml0 package used to provide the shared 51 library for libxml.so.0, you can probably safely remove it. The libxml 52 packages provided on <a href="ftp://xmlsoft.org/libxml2/">xmlsoft.org</a> provide 53 libxml.so.0</p> 54 </li> 55 <li><em>I can't install the libxml(2) RPM package due to failed 56 dependencies</em> 57 <p>The most generic solution is to re-fetch the latest src.rpm , and 58 rebuild it locally with</p> 59 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code>.</p> 60 <p>If everything goes well it will generate two binary rpm packages (one 61 providing the shared libs and xmllint, and the other one, the -devel 62 package, providing includes, static libraries and scripts needed to build 63 applications with libxml(2)) that you can install locally.</p> 64 </li> 65</ol><h3><a name="Compilatio" id="Compilatio">Compilation</a></h3><ol><li><em>What is the process to compile libxml2 ?</em> 66 <p>As most UNIX libraries libxml2 follows the "standard":</p> 67 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p> 68 <p><code>cd libxml-xxxx</code></p> 69 <p><code>/configure --help</code></p> 70 <p>to see the options, then the compilation/installation proper</p> 71 <p><code>/configure [possible options]</code></p> 72 <p><code>make</code></p> 73 <p><code>make install</code></p> 74 <p>At that point you may have to rerun ldconfig or a similar utility to 75 update your list of installed shared libs.</p> 76 </li> 77 <li><em>What other libraries are needed to compile/install libxml2 ?</em> 78 <p>Libxml2 does not require any other library, the normal C ANSI API 79 should be sufficient (please report any violation to this rule you may 80 find).</p> 81 <p>However if found at configuration time libxml2 will detect and use the 82 following libs:</p> 83 <ul><li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a 84 highly portable and available widely compression library.</li> 85 <li>iconv: a powerful character encoding conversion library. It is 86 included by default in recent glibc libraries, so it doesn't need to 87 be installed specifically on Linux. It now seems a <a href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part 88 of the official UNIX</a> specification. Here is one <a href="http://www.gnu.org/software/libiconv/">implementation of the 89 library</a> which source can be found <a href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li> 90 </ul></li> 91 <p></p> 92 <li><em>Make check fails on some platforms</em> 93 <p>Sometimes the regression tests' results don't completely match the 94 value produced by the parser, and the makefile uses diff to print the 95 delta. On some platforms the diff return breaks the compilation process; 96 if the diff is small this is probably not a serious problem.</p> 97 <p>Sometimes (especially on Solaris) make checks fail due to limitations 98 in make. Try using GNU-make instead.</p> 99 </li> 100 <li><em>I use the SVN version and there is no configure script</em> 101 <p>The configure script (and other Makefiles) are generated. Use the 102 autogen.sh script to regenerate the configure script and Makefiles, 103 like:</p> 104 <p><code>/autogen.sh --prefix=/usr --disable-shared</code></p> 105 </li> 106 <li><em>I have troubles when running make tests with gcc-3.0</em> 107 <p>It seems the initial release of gcc-3.0 has a problem with the 108 optimizer which miscompiles the URI module. Please use another 109 compiler.</p> 110 </li> 111</ol><h3><a name="Developer" id="Developer">Developer</a> corner</h3><ol><li><em>Troubles compiling or linking programs using libxml2</em> 112 <p>Usually the problem comes from the fact that the compiler doesn't get 113 the right compilation or linking flags. There is a small shell script 114 <code>xml2-config</code> which is installed as part of libxml2 usual 115 install process which provides those flags. Use</p> 116 <p><code>xml2-config --cflags</code></p> 117 <p>to get the compilation flags and</p> 118 <p><code>xml2-config --libs</code></p> 119 <p>to get the linker flags. Usually this is done directly from the 120 Makefile as:</p> 121 <p><code>CFLAGS=`xml2-config --cflags`</code></p> 122 <p><code>LIBS=`xml2-config --libs`</code></p> 123 </li> 124 <li><em>I want to install my own copy of libxml2 in my home directory and 125 link my programs against it, but it doesn't work</em> 126 <p>There are many different ways to accomplish this. Here is one way to 127 do this under Linux. Suppose your home directory is <code>/home/user. 128 </code>Then:</p> 129 <ul><li>Create a subdirectory, let's call it <code>myxml</code></li> 130 <li>unpack the libxml2 distribution into that subdirectory</li> 131 <li>chdir into the unpacked distribution 132 (<code>/home/user/myxml/libxml2 </code>)</li> 133 <li>configure the library using the "<code>--prefix</code>" switch, 134 specifying an installation subdirectory in 135 <code>/home/user/myxml</code>, e.g. 136 <p><code>/configure --prefix /home/user/myxml/xmlinst</code> {other 137 configuration options}</p> 138 </li> 139 <li>now run <code>make</code> followed by <code>make install</code></li> 140 <li>At this point, the installation subdirectory contains the complete 141 "private" include files, library files and binary program files (e.g. 142 xmllint), located in 143 <p><code>/home/user/myxml/xmlinst/lib, 144 /home/user/myxml/xmlinst/include </code> and <code> 145 /home/user/myxml/xmlinst/bin</code></p> 146 respectively.</li> 147 <li>In order to use this "private" library, you should first add it to 148 the beginning of your default PATH (so that your own private program 149 files such as xmllint will be used instead of the normal system 150 ones). To do this, the Bash command would be 151 <p><code>export PATH=/home/user/myxml/xmlinst/bin:$PATH</code></p> 152 </li> 153 <li>Now suppose you have a program <code>test1.c</code> that you would 154 like to compile with your "private" library. Simply compile it using 155 the command 156 <p><code>gcc `xml2-config --cflags --libs` -o test test.c</code></p> 157 Note that, because your PATH has been set with <code> 158 /home/user/myxml/xmlinst/bin</code> at the beginning, the xml2-config 159 program which you just installed will be used instead of the system 160 default one, and this will <em>automatically</em> get the correct 161 libraries linked with your program.</li> 162 </ul></li> 163 164 <p></p> 165 <li><em>xmlDocDump() generates output on one line.</em> 166 <p>Libxml2 will not <strong>invent</strong> spaces in the content of a 167 document since <strong>all spaces in the content of a document are 168 significant</strong>. If you build a tree from the API and want 169 indentation:</p> 170 <ol><li>the correct way is to generate those yourself too.</li> 171 <li>the dangerous way is to ask libxml2 to add those blanks to your 172 content <strong>modifying the content of your document in the 173 process</strong>. The result may not be what you expect. There is 174 <strong>NO</strong> way to guarantee that such a modification won't 175 affect other parts of the content of your document. See <a href="http://xmlsoft.org/html/libxml-parser.html#xmlKeepBlanksDefault">xmlKeepBlanksDefault 176 ()</a> and <a href="http://xmlsoft.org/html/libxml-tree.html#xmlSaveFormatFile">xmlSaveFormatFile 177 ()</a></li> 178 </ol></li> 179 <p></p> 180 <li><em>Extra nodes in the document:</em> 181 <p><em>For an XML file as below:</em></p> 182 <pre><?xml version="1.0"?> 183<PLAN xmlns="http://www.argus.ca/autotest/1.0/"> 184<NODE CommFlag="0"/> 185<NODE CommFlag="1"/> 186</PLAN></pre> 187 <p><em>after parsing it with the function 188 pxmlDoc=xmlParseFile(...);</em></p> 189 <p><em>I want to the get the content of the first node (node with the 190 CommFlag="0")</em></p> 191 <p><em>so I did it as following;</em></p> 192 <pre>xmlNodePtr pnode; 193pnode=pxmlDoc->children->children;</pre> 194 <p><em>but it does not work. If I change it to</em></p> 195 <pre>pnode=pxmlDoc->children->children->next;</pre> 196 <p><em>then it works. Can someone explain it to me.</em></p> 197 <p></p> 198 <p>In XML all characters in the content of the document are significant 199 <strong>including blanks and formatting line breaks</strong>.</p> 200 <p>The extra nodes you are wondering about are just that, text nodes with 201 the formatting spaces which are part of the document but that people tend 202 to forget. There is a function <a href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault 203 ()</a> to remove those at parse time, but that's an heuristic, and its 204 use should be limited to cases where you are certain there is no 205 mixed-content in the document.</p> 206 </li> 207 <li><em>I get compilation errors of existing code like when accessing 208 <strong>root</strong> or <strong>child fields</strong> of nodes.</em> 209 <p>You are compiling code developed for libxml version 1 and using a 210 libxml2 development environment. Either switch back to libxml v1 devel or 211 even better fix the code to compile with libxml2 (or both) by <a href="upgrade.html">following the instructions</a>.</p> 212 </li> 213 <li><em>I get compilation errors about non existing 214 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong> 215 fields.</em> 216 <p>The source code you are using has been <a href="upgrade.html">upgraded</a> to be able to compile with both libxml 217 and libxml2, but you need to install a more recent version: 218 libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0</p> 219 </li> 220 <li><em>Random crashes in threaded applications</em> 221 <p>Read and follow all advices on the <a href="threads.html">thread 222 safety</a> page, and make 100% sure you never call xmlCleanupParser() 223 while the library or an XML document might still be in use by another 224 thread.</p> 225 </li> 226 <li><em>The example provided in the web page does not compile.</em> 227 <p>It's hard to maintain the documentation in sync with the code 228 <grin/> ...</p> 229 <p>Check the previous points 1/ and 2/ raised before, and please send 230 patches.</p> 231 </li> 232 <li><em>Where can I get more examples and information than provided on the 233 web page?</em> 234 <p>Ideally a libxml2 book would be nice. I have no such plan ... But you 235 can:</p> 236 <ul><li>check more deeply the <a href="html/libxml-lib.html">existing 237 generated doc</a></li> 238 <li>have a look at <a href="examples/index.html">the set of 239 examples</a>.</li> 240 <li>look for examples of use for libxml2 function using the Gnome code 241 or by asking on Google.</li> 242 <li><a href="http://svn.gnome.org/viewvc/libxml2/trunk/">Browse 243 the libxml2 source</a> , I try to write code as clean and documented 244 as possible, so looking at it may be helpful. In particular the code 245 of <a href="http://svn.gnome.org/viewvc/libxml2/trunk/xmllint.c?view=markup">xmllint.c</a> and of the various testXXX.c test programs should 246 provide good examples of how to do things with the library.</li> 247 </ul></li> 248 <p></p> 249 <li><em>What about C++ ?</em> 250 <p>libxml2 is written in pure C in order to allow easy reuse on a number 251 of platforms, including embedded systems. I don't intend to convert to 252 C++.</p> 253 <p>There is however a C++ wrapper which may fulfill your needs:</p> 254 <ul><li>by Ari Johnson <ari@btigate.com>: 255 <p>Website: <a href="http://libxmlplusplus.sourceforge.net/">http://libxmlplusplus.sourceforge.net/</a></p> 256 <p>Download: <a href="http://sourceforge.net/project/showfiles.php?group_id=12999">http://sourceforge.net/project/showfiles.php?group_id=12999</a></p> 257 </li> 258 </ul></li> 259 <li><em>How to validate a document a posteriori ?</em> 260 <p>It is possible to validate documents which had not been validated at 261 initial parsing time or documents which have been built from scratch 262 using the API. Use the <a href="http://xmlsoft.org/html/libxml-valid.html#xmlValidateDtd">xmlValidateDtd()</a> 263 function. It is also possible to simply add a DTD to an existing 264 document:</p> 265 <pre>xmlDocPtr doc; /* your existing document */ 266xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */ 267 268 dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */ 269 270 doc->intSubset = dtd; 271 if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd); 272 else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd); 273 </pre> 274 </li> 275 <li><em>So what is this funky "xmlChar" used all the time?</em> 276 <p>It is a null terminated sequence of utf-8 characters. And only utf-8! 277 You need to convert strings encoded in different ways to utf-8 before 278 passing them to the API. This can be accomplished with the iconv library 279 for instance.</p> 280 </li> 281 <li>etc ...</li> 282</ol><p></p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html> 283
