FAQ.html revision b7c29c38f507ac62cc85df9b897762fc84f05a68
1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 5<link rel="SHORTCUT ICON" href="/favicon.ico"> 6<style type="text/css"><!-- 7TD {font-family: Verdana,Arial,Helvetica} 8BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em} 9H1 {font-family: Verdana,Arial,Helvetica} 10H2 {font-family: Verdana,Arial,Helvetica} 11H3 {font-family: Verdana,Arial,Helvetica} 12A:link, A:visited, A:active { text-decoration: underline } 13--></style> 14<title>FAQ</title> 15</head> 16<body bgcolor="#8b7765" text="#000000" link="#000000" vlink="#000000"> 17<table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr> 18<td width="180"> 19<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 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href="APIfunctions.html">Functions/Types</a></li> 70<li><a href="APIfiles.html">Modules</a></li> 71<li><a href="APIsymbols.html">Symbols</a></li> 72</ul></td></tr> 73</table> 74<table width="100%" border="0" cellspacing="1" cellpadding="3"> 75<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr> 76<tr><td bgcolor="#fffacd"><ul> 77<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li> 78<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li> 79<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li> 80<li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li> 81<li><a href="ftp://xmlsoft.org/">FTP</a></li> 82<li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li> 83<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li> 84<li><a href="http://www.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li> 85<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li> 86<li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml&product=libxml2">Bug Tracker</a></li> 87</ul></td></tr> 88</table> 89</td></tr></table></td> 90<td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table 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"> 91<p>Table of Contents:</p> 92<ul> 93<li><a href="FAQ.html#License">License(s)</a></li> 94 <li><a href="FAQ.html#Installati">Installation</a></li> 95 <li><a href="FAQ.html#Compilatio">Compilation</a></li> 96 <li><a href="FAQ.html#Developer">Developer corner</a></li> 97</ul> 98<h3> 99<a name="License">License</a>(s)</h3> 100<ol> 101<li> 102<em>Licensing Terms for libxml</em> 103 <p>libxml is released under the <a href="http://www.opensource.org/licenses/mit-license.html">MIT 104 License</a>; see the file Copyright in the distribution for the precise 105 wording</p> 106 </li> 107 <li> 108<em>Can I embed libxml in a proprietary application ?</em> 109 <p>Yes. The MIT License allows you to keep proprietary the changes you 110 made to libxml, but it would be graceful to send-back bug fixes and 111 improvements as patches for possible incorporation in the main 112 development tree.</p> 113 </li> 114</ol> 115<h3><a name="Installati">Installation</a></h3> 116<ol> 117<li>Unless you are forced to because your application links with a Gnome 118 library requiring it, <strong><span style="background-color: #FF0000">Do 119 Not Use libxml1</span></strong>, use libxml2</li> 120 <li> 121<em>Where can I get libxml</em> ? 122 <p>The original distribution comes from <a href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.4/">gnome.org</a> 123</p> 124 <p>Most Linux and BSD distributions include libxml, this is probably the 125 safer way for end-users to use libxml.</p> 126 <p>David Doolin provides precompiled Windows versions at <a href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/%20%20%20%20%20%20%20%20%20">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a> 127</p> 128 </li> 129 <li> 130<em>I see libxml and libxml2 releases, which one should I install ?</em> 131 <ul> 132<li>If you are not constrained by backward compatibility issues with 133 existing applications, install libxml2 only</li> 134 <li>If you are not doing development, you can safely install both. 135 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 136 compatible (this is not the case for development packages).</li> 137 <li>If you are a developer and your system provides separate packaging 138 for shared libraries and the development components, it is possible 139 to install libxml and libxml2, and also <a href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a> 140 and <a href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a> 141 too for libxml2 >= 2.3.0</li> 142 <li>If you are developing a new application, please develop against 143 libxml2(-devel)</li> 144 </ul> 145</li> 146 <li> 147<em>I can't install the libxml package, it conflicts with libxml0</em> 148 <p>You probably have an old libxml0 package used to provide the shared 149 library for libxml.so.0, you can probably safely remove it. The libxml 150 packages provided on <a href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provide 151 libxml.so.0</p> 152 </li> 153 <li> 154<em>I can't install the libxml(2) RPM package due to failed 155 dependencies</em> 156 <p>The most generic solution is to re-fetch the latest src.rpm , and 157 rebuild it locally with</p> 158 <p> 159<code>rpm --rebuild libxml(2)-xxx.src.rpm</code>.</p> 160 <p>If everything goes well it will generate two binary rpm packages (one 161 providing the shared libs and xmllint, and the other one, the -devel 162 package, providing includes, static libraries and scripts needed to build 163 applications with libxml(2)) that you can install locally.</p> 164 </li> 165</ol> 166<h3><a name="Compilatio">Compilation</a></h3> 167<ol> 168<li> 169<em>What is the process to compile libxml ?</em> 170 <p>As most UNIX libraries libxml follows the "standard":</p> 171 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p> 172 <p><code>cd libxml-xxxx</code></p> 173 <p><code>/configure --help</code></p> 174 <p>to see the options, then the compilation/installation proper</p> 175 <p><code>/configure [possible options]</code></p> 176 <p><code>make</code></p> 177 <p><code>make install</code></p> 178 <p>At that point you may have to rerun ldconfig or a similar utility to 179 update your list of installed shared libs.</p> 180 </li> 181 <li> 182<em>What other libraries are needed to compile/install libxml ?</em> 183 <p>Libxml does not require any other library, the normal C ANSI API 184 should be sufficient (please report any violation to this rule you may 185 find).</p> 186 <p>However if found at configuration time libxml will detect and use the 187 following libs:</p> 188 <ul> 189<li> 190<a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a 191 highly portable and available widely compression library.</li> 192 <li>iconv: a powerful character encoding conversion library. It is 193 included by default in recent glibc libraries, so it doesn't need to 194 be installed specifically on Linux. It now seems a <a href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part 195 of the official UNIX</a> specification. Here is one <a href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation 196 of the library</a> which source can be found <a href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li> 197 </ul> 198</li> 199 <li> 200<em>Make check fails on some platforms</em> 201 <p>Sometimes the regression tests' results don't completely match the 202 value produced by the parser, and the makefile uses diff to print the 203 delta. On some platforms the diff return breaks the compilation process; 204 if the diff is small this is probably not a serious problem.</p> 205 <p>Sometimes (especially on Solaris) make checks fail due to limitations 206 in make. Try using GNU-make instead.</p> 207 </li> 208 <li> 209<em>I use the CVS version and there is no configure script</em> 210 <p>The configure script (and other Makefiles) are generated. Use the 211 autogen.sh script to regenerate the configure script and Makefiles, 212 like:</p> 213 <p><code>/autogen.sh --prefix=/usr --disable-shared</code></p> 214 </li> 215 <li> 216<em>I have troubles when running make tests with gcc-3.0</em> 217 <p>It seems the initial release of gcc-3.0 has a problem with the 218 optimizer which miscompiles the URI module. Please use another 219 compiler.</p> 220 </li> 221</ol> 222<h3> 223<a name="Developer">Developer</a> corner</h3> 224<ol> 225<li> 226<em>xmlDocDump() generates output on one line.</em> 227 <p>Libxml will not <strong>invent</strong> spaces in the content of a 228 document since <strong>all spaces in the content of a document are 229 significant</strong>. If you build a tree from the API and want 230 indentation:</p> 231 <ol> 232<li>the correct way is to generate those yourself too.</li> 233 <li>the dangerous way is to ask libxml to add those blanks to your 234 content <strong>modifying the content of your document in the 235 process</strong>. The result may not be what you expect. There is 236 <strong>NO</strong> way to guarantee that such a modification won't 237 affect other parts of the content of your document. See <a href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault 238 ()</a> and <a href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile 239 ()</a> 240</li> 241 </ol> 242</li> 243 <li>Extra nodes in the document: 244 <p><em>For a XML file as below:</em></p> 245 <pre><?xml version="1.0"?> 246<PLAN xmlns="http://www.argus.ca/autotest/1.0/">; 247<NODE CommFlag="0"/> 248<NODE CommFlag="1"/> 249</PLAN></pre> 250 <p><em>after parsing it with the function 251 pxmlDoc=xmlParseFile(...);</em></p> 252 <p><em>I want to the get the content of the first node (node with the 253 CommFlag="0")</em></p> 254 <p><em>so I did it as following;</em></p> 255 <pre>xmlNodePtr pnode; 256pnode=pxmlDoc->children->children;</pre> 257 <p><em>but it does not work. If I change it to</em></p> 258 <pre>pnode=pxmlDoc->children->children->next;</pre> 259 <p><em>then it works. Can someone explain it to me.</em></p> 260 <p> 261 <p>In XML all characters in the content of the document are significant 262 <strong>including blanks and formatting line breaks</strong>.</p> 263 <p>The extra nodes you are wondering about are just that, text nodes with 264 the formatting spaces which are part of the document but that people tend 265 to forget. There is a function <a href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault 266 ()</a> to remove those at parse time, but that's an heuristic, and its 267 use should be limited to cases where you are certain there is no 268 mixed-content in the document.</p> 269 </li> 270 <li> 271<em>I get compilation errors of existing code like when accessing 272 <strong>root</strong> or <strong>child fields</strong> of nodes.</em> 273 <p>You are compiling code developed for libxml version 1 and using a 274 libxml2 development environment. Either switch back to libxml v1 devel or 275 even better fix the code to compile with libxml2 (or both) by <a href="upgrade.html">following the instructions</a>.</p> 276 </li> 277 <li> 278<em>I get compilation errors about non existing 279 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong> 280 fields.</em> 281 <p>The source code you are using has been <a href="upgrade.html">upgraded</a> to be able to compile with both libxml 282 and libxml2, but you need to install a more recent version: 283 libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0</p> 284 </li> 285 <li> 286<em>XPath implementation looks seriously broken</em> 287 <p>XPath implementation prior to 2.3.0 was really incomplete. Upgrade to 288 a recent version, there are no known bugs in the current version.</p> 289 </li> 290 <li> 291<em>The example provided in the web page does not compile.</em> 292 <p>It's hard to maintain the documentation in sync with the code 293 <grin/> ...</p> 294 <p>Check the previous points 1/ and 2/ raised before, and please send 295 patches.</p> 296 </li> 297 <li> 298<em>Where can I get more examples and information than privoded on the 299 web page?</em> 300 <p>Ideally a libxml book would be nice. I have no such plan ... But you 301 can:</p> 302 <ul> 303<li>check more deeply the <a href="html/libxml-lib.html">existing 304 generated doc</a> 305</li> 306 <li>look for examples of use for libxml function using the Gnome code. 307 For example the following will query the full Gnome CVS base for the 308 use of the <strong>xmlAddChild()</strong> function: 309 <p><a href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p> 310 <p>This may be slow, a large hardware donation to the gnome project 311 could cure this :-)</p> 312 </li> 313 <li> 314<a href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Browse 315 the libxml source</a> , I try to write code as clean and documented 316 as possible, so looking at it may be helpful. In particular the code 317 of xmllint.c and of the various testXXX.c test programs should 318 provide good examples of how to do things with the library.</li> 319 </ul> 320</li> 321 <li>What about C++ ? 322 <p>libxml is written in pure C in order to allow easy reuse on a number 323 of platforms, including embedded systems. I don't intend to convert to 324 C++.</p> 325 <p>There are however a few C++ wrappers which may fulfill your needs:</p> 326 <ul> 327<li>by Ari Johnson <ari@btigate.com>: 328 <p>Website: <a href="http://lusis.org/~ari/xml%2B%2B/">http://lusis.org/~ari/xml++/</a> 329</p> 330 <p>Download: <a href="http://lusis.org/~ari/xml%2B%2B/libxml%2B%2B.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a> 331</p> 332 </li> 333 <li>by Peter Jones <pjones@pmade.org> 334 <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a> 335</p> 336 </li> 337 </ul> 338</li> 339 <li>How to validate a document a posteriori ? 340 <p>It is possible to validate documents which had not been validated at 341 initial parsing time or documents which have been built from scratch 342 using the API. Use the <a href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a> 343 function. It is also possible to simply add a DTD to an existing 344 document:</p> 345 <pre>xmlDocPtr doc; /* your existing document */ 346xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */ 347 348 dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */ 349 350 doc->intSubset = dtd; 351 if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd); 352 else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd); 353 </pre> 354 </li> 355 <li>etc ...</li> 356</ol> 357<p> 358<p><a href="bugs.html">Daniel Veillard</a></p> 359</td></tr></table></td></tr></table></td></tr></table></td> 360</tr></table></td></tr></table> 361</body> 362</html> 363
