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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"> 4: TD {font-family: Verdana,Arial,Helvetica} 5: BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em} 6: H1 {font-family: Verdana,Arial,Helvetica} 7: H2 {font-family: Verdana,Arial,Helvetica} 8: H3 {font-family: Verdana,Arial,Helvetica} 9: A: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 width="180"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C Logo" /></a><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XML C parser and toolkit of Gnome</h1><h2>FAQ</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center>Main Menu</center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html">Home</a></li><li><a href="html/index.html">Reference Manual</a></li><li><a href="intro.html">Introduction</a></li><li><a href="FAQ.html">FAQ</a></li><li><a href="docs.html" style="font-weight:bold">Developer Menu</a></li><li><a href="bugs.html">Reporting bugs and getting help</a></li><li><a href="help.html">How to help</a></li><li><a href="downloads.html">Downloads</a></li><li><a href="news.html">Releases</a></li><li><a href="XMLinfo.html">XML</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="xmldtd.html">Validation & DTDs</a></li><li><a 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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">Table of Contents:<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>Licensing Terms for libxml 15: 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 18: </li> 19: <li>Can I embed libxml2 in a proprietary application ? 20: 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. 24: </li> 25: </ol><h3><a name="Installati" id="Installati">Installation</a></h3><ol><li>Do Not Use 26: libxml1, use libxml2</li> 27:  28: <li>Where can I get libxml ? 29: 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> 30: Most Linux and BSD distributions include libxml, this is probably the 31: safer way for end-users to use libxml. 32: 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> 33: </li> 34:  35: <li>I see libxml and libxml2 releases, which one should I install ? 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>I can't install the libxml package, it conflicts with libxml0 50: 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 54: </li> 55: <li>I can't install the libxml(2) RPM package due to failed 56: dependencies 57: The most generic solution is to re-fetch the latest src.rpm , and 58: rebuild it locally with 59: <code>rpm --rebuild libxml(2)-xxx.src.rpm</code>. 60: 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. 64: </li> 65: </ol><h3><a name="Compilatio" id="Compilatio">Compilation</a></h3><ol><li>What is the process to compile libxml2 ? 66: As most UNIX libraries libxml2 follows the "standard": 67: <code>gunzip -c xxx.tar.gz | tar xvf -</code> 68: <code>cd libxml-xxxx</code> 69: <code>./configure --help</code> 70: to see the options, then the compilation/installation proper 71: <code>./configure [possible options]</code> 72: <code>make</code> 73: <code>make install</code> 74: At that point you may have to rerun ldconfig or a similar utility to 75: update your list of installed shared libs. 76: </li> 77: <li>What other libraries are needed to compile/install libxml2 ? 78: 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). 81: However if found at configuration time libxml2 will detect and use the 82: following libs: 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:  92: <li>Make check fails on some platforms 93: 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. 97: Sometimes (especially on Solaris) make checks fail due to limitations 98: in make. Try using GNU-make instead. 99: </li> 100: <li>I use the SVN version and there is no configure script 101: The configure script (and other Makefiles) are generated. Use the 102: autogen.sh script to regenerate the configure script and Makefiles, 103: like: 104: <code>./autogen.sh --prefix=/usr --disable-shared</code> 105: </li> 106: <li>I have troubles when running make tests with gcc-3.0 107: 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. 110: </li> 111: </ol><h3><a name="Developer" id="Developer">Developer</a> corner</h3><ol><li>Troubles compiling or linking programs using libxml2 112: 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 116: <code>xml2-config --cflags</code> 117: to get the compilation flags and 118: <code>xml2-config --libs</code> 119: to get the linker flags. Usually this is done directly from the 120: Makefile as: 121: <code>CFLAGS=`xml2-config --cflags`</code> 122: <code>LIBS=`xml2-config --libs`</code> 123: </li> 124: <li>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 126: 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: 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: <code>./configure --prefix /home/user/myxml/xmlinst</code> {other 137: configuration options} 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: <code>/home/user/myxml/xmlinst/lib, 144: /home/user/myxml/xmlinst/include </code> and <code> 145: /home/user/myxml/xmlinst/bin</code> 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: <code>export PATH=/home/user/myxml/xmlinst/bin:$PATH</code> 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: <code>gcc `xml2-config --cflags --libs` -o test test.c</code> 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 automatically get the correct 161: libraries linked with your program.</li> 162: </ul></li> 163: 164:  165: <li>xmlDocDump() generates output on one line. 166: Libxml2 will not invent spaces in the content of a 167: document since all spaces in the content of a document are 168: significant. If you build a tree from the API and want 169: indentation: 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 modifying the content of your document in the 173: process. The result may not be what you expect. There is 174: NO 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:  180: <li>Extra nodes in the document: 181: For an XML file as below: 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: after parsing it with the function 188: pxmlDoc=xmlParseFile(...); 189: I want to the get the content of the first node (node with the 190: CommFlag="0") 191: so I did it as following; 192: <pre>xmlNodePtr pnode; 193: pnode=pxmlDoc->children->children;</pre> 194: but it does not work. If I change it to 195: <pre>pnode=pxmlDoc->children->children->next;</pre> 196: then it works. Can someone explain it to me. 197:  198: In XML all characters in the content of the document are significant 199: including blanks and formatting line breaks. 200: 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. 206: </li> 207: <li>I get compilation errors of existing code like when accessing 208: root or child fields of nodes. 209: 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>. 212: </li> 213: <li>I get compilation errors about non existing 214: xmlRootNode or xmlChildrenNode 215: fields. 216: 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) >= 2.1.0 219: </li> 220: <li>Random crashes in threaded applications 221: 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. 225: </li> 226: <li>The example provided in the web page does not compile. 227: It's hard to maintain the documentation in sync with the code 228: <grin/> ... 229: Check the previous points 1/ and 2/ raised before, and please send 230: patches. 231: </li> 232: <li>Where can I get more examples and information than provided on the 233: web page? 234: Ideally a libxml2 book would be nice. I have no such plan ... But you 235: can: 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:  249: <li>What about C++ ? 250: 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++. 253: There is however a C++ wrapper which may fulfill your needs: 254: <ul><li>by Ari Johnson <ari@btigate.com>: 255: Website: <a href="http://libxmlplusplus.sourceforge.net/">http://libxmlplusplus.sourceforge.net/</a> 256: Download: <a href="http://sourceforge.net/project/showfiles.php?group_id=12999">http://sourceforge.net/project/showfiles.php?group_id=12999</a> 257: </li> 258: </ul></li> 259: <li>How to validate a document a posteriori ? 260: 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: 265: <pre>xmlDocPtr doc; /* your existing document */ 266: xmlDtdPtr 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>So what is this funky "xmlChar" used all the time? 276: 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. 280: </li> 281: <li>etc ...</li> 282: </ol><a href="bugs.html">Daniel Veillard</a></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>