Google Git
Sign in
apache / xalan-j / 253c28575f89f9f8731d24b00e6c7450c6d3cd2b / . / xalan-j / faq.html
blob: fc5d25681d33e82cf01c82253f05ff6aa72845b9 [file] [log] [blame]
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<title>ASF: Frequently asked questions</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<link rel="stylesheet" type="text/css" href="resources/apache-xalan.css" />
</head>
<!--
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
-->
<body>
<div id="title">
<table class="HdrTitle">
<tbody>
<tr>
<th rowspan="2">
<a href="../index.html">
<img alt="Trademark Logo" src="resources/XalanJ-Logo-tm.png" width="190" height="90" />
</a>
</th>
<th text-align="center" width="75%">
<a href="index.html">Xalan XSL Transformer User's Guide</a>
</th>
</tr>
<tr>
<td valign="middle">Frequently asked questions</td>
</tr>
</tbody>
</table>
<table class="HdrButtons" align="center" border="1">
<tbody>
<tr>
<td>
<a href="http://www.apache.org">Apache Foundation</a>
</td>
<td>
<a href="http://xalan.apache.org">Xalan Project</a>
</td>
<td>
<a href="http://xerces.apache.org">Xerces Project</a>
</td>
<td>
<a href="http://www.w3.org/TR">Web Consortium</a>
</td>
<td>
<a href="http://www.oasis-open.org/standards">Oasis Open</a>
</td>
</tr>
</tbody>
</table>
</div>
<div id="navLeft">
<ul>
<li>
<a href="resources.html">Resources</a>
<br />
</li>
<li>
<a href="http://xalan.apache.org/index.html">Home</a>
</li></ul><hr /><ul>
<li>
<a href="index.html">Xalan-J 2.7.2</a>
</li>
<li>
<a href="charter.html">Charter</a>
</li></ul><hr /><ul>
<li>
<a href="whatsnew.html">What's New</a>
</li>
<li>
<a href="readme.html">Release Notes</a>
</li></ul><hr /><ul>
<li>
<a href="overview.html">Overview</a>
</li>
<li>
<a href="downloads.html">Download/Build</a>
</li>
<li>
<a href="getstarted.html">Getting Started</a>
</li>
<li>
<a href="xsltc_usage.html">Using XSLTC</a>
</li></ul><hr /><ul>
<li>FAQs<br />
</li></ul><hr /><ul>
<li>
<a href="samples.html">Sample Apps</a>
</li>
<li>
<a href="commandline.html">Command Line</a>
</li></ul><hr /><ul>
<li>
<a href="features.html">Features</a>
</li>
<li>
<a href="trax.html">Transform API</a>
</li>
<li>
<a href="xpath_apis.html">XPath API</a>
</li>
<li>
<a href="usagepatterns.html">Usage Patterns</a>
</li></ul><hr /><ul>
<li>
<a href="apidocs/index.html">Xalan-J API</a>
</li>
<li>
<a href="public_apis.html">Public APIs</a>
</li>
<li>
<a href="dtm.html">DTM</a>
</li></ul><hr /><ul>
<li>
<a href="extensions.html">Extensions</a>
</li>
<li>
<a href="extensionslib.html">Extensions Library</a>
</li>
<li>
<a href="extensions_xsltc.html">XSLTC Exts</a>
</li></ul><hr /><ul>
<li>
<a href="design/design2_0_0.html">Xalan 2 Design</a>
</li>
<li>
<a href="xsltc/index.html">XSLTC Design</a>
</li></ul><hr /><ul>
<li>
<a href="builds.html">Building a release</a>
</li>
<li>
<a href="http://xml.apache.org/xalan-j/test/overview.html">Testing</a>
</li>
<li>
<a href="bugreporting.html">Bug Reporting</a>
</li></ul><hr /><ul>
<li>
<a href="contact_us.html">Contact us</a>
</li>
</ul>
</div>
<div id="content">
<h2 class="faqSubHead">Questions</h2>
<h3>General XSLT</h3>
<ol start="1">
<li>
<a href="#faq-1">Where do I go to learn about XSLT</a>
</li>
<li>
<a href="#faq-2">Where can I ask questions about XSLT</a>
</li>
<li>
<a href="#faq-3">TrAX and JAXP</a>
</li>
</ol>
<h3>Versions</h3>
<ol start="4">
<li>
<a href="#faq-4">Determining Xalan-Java Version</a>
</li>
<li>
<a href="#faq-5">Determining the Serializer Version</a>
</li>
<li>
<a href="#faq-6">Which version of Xerces should I be using?</a>
</li>
<li>
<a href="#faq-7">Compatibility with Xalan-Java version 1</a>
</li>
<li>
<a href="#faq-8">Issues running Xalan-Java on JDK 1.3</a>
</li>
<li>
<a href="#faq-9">Issues running Xalan-Java on JDK/JRE 1.4 or higher</a>
</li>
<li>
<a href="#faq-10">Issues running Xalan-Java on Tomcat with JDK 1.4</a>
</li>
<li>
<a href="#faq-11">Issues running Applets with XSLTC in Web Browsers with JAVA Plug-in (JRE 1.4)</a>
</li>
<li>
<a href="#faq-12">Using the 'signature' file to verify a download</a>
</li>
</ol>
<h3>Performance Issues</h3>
<ol start="13">
<li>
<a href="#faq-13">Speeding up transformations</a>
</li>
<li>
<a href="#faq-14">JAXP factory lookup procedure</a>
</li>
</ol>
<h3>Namespace Related</h3>
<ol start="15">
<li>
<a href="#faq-15">Retrieving nodes in the default namespace</a>
</li>
<li>
<a href="#faq-16">Setting the parser to be namespace aware</a>
</li>
</ol>
<h3>Common Errors</h3>
<ol start="17">
<li>
<a href="#faq-17">NoClassDefFound errors</a>
</li>
<li>
<a href="#faq-18">a "DOM006 Hierarchy request error"</a>
</li>
<li>
<a href="#faq-19">Namespace not supported by SAXParser</a>
</li>
<li>
<a href="#faq-20">Missing xsl:version attribute error</a>
</li>
<li>
<a href="#faq-21">StackOverflowError with recursive stylesheet</a>
</li>
<li>
<a href="#faq-22">OutOfMemoryError processing multiple documents</a>
</li>
<li>
<a href="#faq-23">File Not Found error</a>
</li>
<li>
<a href="#faq-24">No more DTM IDs are available</a>
</li>
<li>
<a href="#faq-25">IllegalAccessError or could not load output_xml.properties on JDK 1.4</a>
</li>
</ol>
<h3>Miscellaneous</h3>
<ol start="26">
<li>
<a href="#faq-26">Chaining transformations</a>
</li>
<li>
<a href="#faq-27">Stylesheet validation</a>
</li>
<li>
<a href="#faq-28">Setting output encoding</a>
</li>
<li>
<a href="#faq-29">Getting line and column numbers for errors in XML input documents and XSL stylesheets</a>
</li>
<li>
<a href="#faq-30">Servlet unable to find classes for extension functions/elements</a>
</li>
<li>
<a href="#faq-31">Translet name doesn't match stylesheet name</a>
</li>
</ol>
<h2 class="faqSubHead">Answers</h2>
<h3 id="faq-1" class="faqTitle">1. Where do I go to learn about XSLT</h3>
<div class="faqQuestion">Where do I go to learn about XSLT?</div>
<br />
<hr />
<div class="faqAnswer">
<p>The definitive sources are the W3C XSLT and XPath recommendations:
<a href="http://www.w3.org/TR/xslt">XSL Transformations (XSLT) Version 1.0</a> and
<a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0</a>.
</p>
<p>For a brief listing of tutorials, discussion forums, and other materials, see
<a href="overview.html#uptospeed">Getting up to speed with XSLT</a>.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-2" class="faqTitle">2. Where can I ask questions about XSLT</h3>
<div class="faqQuestion">Where can I ask questions about XSLT?</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a href="http://marc.theaimsgroup.com/?l=xalan-dev&amp;r=1&amp;w=2">xalan-dev</a> and
<a href="http://marc.theaimsgroup.com/?l=xalan-j-users&amp;r=1&amp;w=2">xalan-j-users</a>
are for Xalan-Java questions only. This is not the best
forum to ask general XSLT questions. The <a href="http://mulberrytech.com/xsl/xsl-list/index.html">Mulberry XSL Mailing List</a> is an
excellent place to ask XSLT questions; please search
<a href="http://www.dpawson.co.uk/xsl/">XSL Frequently Asked Questions</a> to ensure your question has not been already asked.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-3" class="faqTitle">3. TrAX and JAXP</h3>
<div class="faqQuestion">What are TrAX and JAXP, and are they related?</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="trax">‌</a>
</p>
<p>TrAX is the Transformation API for XML. In November 2000, TrAX was revised and incorporated
into JAXP, the JAVA API for XML Processing. JAXP (including TrAX) provides users a standard,
vendor-neutral API for working with (and transforming) XML documents. You can use this API
to build applications that are not bound to the particular implementation details of a given
XML parser or XSL transformer.</p>
<p>Xalan-Java includes the JAXP packages, implements the TrAX portion of
that API (javax.xml.transform....), implements the XPath API of JAXP (javax.xml.xpath....),
and includes xercesImpl.jar from
<a href="http://xerces.apache.org/xerces2-j/index.html">Xerces-Java 2.11.0</a>, which implements the parser portion of the API
(javax.xml.parser....).</p>
<p>For more information, see <a href="trax.html">Using the JAXP Transform APIs</a> and
<a href="https://jaxp.java.net/">Java API for XML Processing (JAXP) 1.3</a>.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-4" class="faqTitle">4. Determining Xalan-Java Version</h3>
<div class="faqQuestion">How do I see what version of Xalan-Java I'm running? How do I determine
which parser I'm using?</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="environmentcheck">‌</a>
</p>
<p>
<b>Using the EnvironmentCheck utility:</b> To help diagnose classpath problems and also
determine which version of Xalan-Java is being used, try running
Xalan-Java's environment checking utility.
</p>
<p>You can run this utility from the command line as follows:</p>
<p>
<code>java org.apache.xalan.xslt.EnvironmentCheck [-out outFile]</code>
</p>
<p>You can also call this utility from within your application. For example,</p>
<p>
<code>boolean environmentOK = (new EnvironmentCheck()).checkEnvironment (yourPrintWriter);</code>
</p>
<p>Be sure to run EnvironmentCheck in the environment where you are experiencing the problem.
For example, if you get a NoClassDefFound error from a command-line application, run
EnvironmentCheck on the command line with exactly the same classpath. If the error occurs
inside your Java application (or in a servlet, etc.), be sure to call the EnvironmentCheck
checkEnvironment(...) method from within your running application.</p>
<p>Best of all, you can call checkEnvironment from a stylesheet using extensions:</p>
<blockquote class="source">
<pre>
&lt;?xml version="1.0"?&gt;
&lt;xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"
xmlns:xalan="http://xml.apache.org/xalan"
exclude-result-prefixes="xalan"&gt;
&lt;xsl:output indent="yes"/&gt;
&lt;xsl:template match="/"&gt;
&lt;out&gt;
&lt;xsl:copy-of select="xalan:checkEnvironment()"/&gt;
&lt;/out&gt;
&lt;/xsl:template&gt;
&lt;/xsl:stylesheet&gt;</pre>
</blockquote>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-5" class="faqTitle">5. Determining the Serializer Version</h3>
<div class="faqQuestion">How do I see what version of the Serializer I'm running? </div>
<br />
<hr />
<div class="faqAnswer">
<a name="serlializercheck">‌</a>
<p>
Xalan's serialier is now shared with Xerces. It may be packaged in Xalan, or Xerces,
or in the JRE itself. You can run the serializer's <b>Version</b> utility from the command line as follows:
</p>
<p>
<code>java org.apache.xml.serializer.Version</code>
</p>
The output should indicate which serializer you are using.
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-6" class="faqTitle">6. Which version of Xerces should I be using?</h3>
<div class="faqQuestion">Which version of Xerces-Java should I be using?</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a href="http://xalan.apache.org/xalan-j">Xalan-Java Version 2.7.2</a> has been tested with <a href="http://xerces.apache.org/xerces2-j/index.html">Xerces-Java 2.11.0</a>.
See <a href="readme.html#status">Status</a>.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-7" class="faqTitle">7. Compatibility with Xalan-Java version 1</h3>
<div class="faqQuestion">How do I run applications that use the Xalan-Java version 1 API with Xalan-Java</div>
<br />
<hr />
<div class="faqAnswer">
<p>The Xalan-Java version 1 compatibility API has been deprecated and removed, so you
must use the Xalan-Java version 2 API. We strongly encourage you to use the
<a href="https://jaxp.java.net/">Java API for XML Processing (JAXP) 1.3</a>. For more information, see
the FAQ on <a href="#trax">TrAX and JAXP.</a>
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-8" class="faqTitle">8. Issues running Xalan-Java on JDK 1.3</h3>
<div class="faqQuestion">I'm having a problem building or running Xalan-Java on the JDK 1.3.</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="jdk13">‌</a>
</p>
<p>The JDK 1.3 automatically places everything in the lib/ext directory in front of everything
you place on the classpath. If this directory contains a version of DOM, JAXP, or Xerces
that predates the Xalan-Java distribution you are using, you may have problems!</p>
<p>The IBM JDK 1.3 includes an earlier version of xerces.jar in the lib/ext directory, a
version that does not implement the JAXP 1.3 interfaces and therefore does not work with the
current Xalan-Java release. Accordingly, you must either remove the
xerces.jar that is in that directory or replace it with the xercesImpl.jar that is included
with the Xalan-Java distribution.</p>
<p>The SUN JDK 1.3 includes a pre-1.1 version of the JAXP in crimson.jar. Either remove the
crimson.jar in that directory or overwrite it with a newer crimson.jar that includes and
implements the JAXP 1.3 interfaces.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-9" class="faqTitle">9. Issues running Xalan-Java on JDK/JRE 1.4 or higher</h3>
<div class="faqQuestion">I'm having a problem running Xalan-Java on JDK/JRE 1.4 or higher</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="jdk14">‌</a>
</p>
<p>JDK/JRE 1.4, and JDK/JRE 5.0 is packaged with an old version of Xalan-Java. The JDK/JRE
will attempt to use this version instead of any on the classpath. Unfortunately,
this causes problems when attempting to use a newer version of Xalan-Java.</p>
<p>You can always determine which version of Xalan-Java you are running
by using the <a href="#environmentcheck">EnvironmentCheck</a> class or by using the
xalan:checkEnvironment extension function. It is highly recommended that you use this
method to verify the version of Xalan-Java you are running, especially
before opening a bug report.</p>
<p>To use a newer version of Xalan-Java and override the one packaged with the JDK:</p>
<ul>
<li>use the
<a href="http://java.sun.com/j2se/1.4.2/docs/guide/standards/">Endorsed Standards Override Mechanism</a>. Place the xalan.jar, serializer.jar, xercesImpl.jar
and xml-apis.jar in the
&lt;java-home&gt;\lib\endorsed directory, where
&lt;java-home&gt; is where the runtime software is installed.
</li>
</ul>
<p>The following methods
<b>do not work</b>:
</p>
<ul>
<li>Using the CLASSPATH environment variable or using -classpath to place the new classes
in the classpath.</li>
<li>Using the -jar option to explicitly execute the classes inside the new jar files.</li>
</ul>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-10" class="faqTitle">10. Issues running Xalan-Java on Tomcat with JDK 1.4</h3>
<div class="faqQuestion">I got java.lang.IllegalAccessError running Xalan-Java on Tomcat with JDK 1.4.</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="tomcat">‌</a>
</p>
<p>
<a href="http://tomcat.apache.org/index.html">jakarta-tomcat 4.1.*</a> is packed
with an old version of xercesImpl.jar. Based on the <a href="http://java.sun.com/j2se/1.4.2/docs/guide/standards/">Endorsed Standards Override Mechanism</a>, you should
replace it with the newer xercesImpl.jar. You should add a newer xalan.jar and serializer.jar
to Tomcat as well.
Read the FAQ about <a href="#jdk14">Issues running Xalan-Java on JDK/JRE 1.4 or higher</a>. Place the
xalan.jar, serializer.jar, and xercesImpl.jar in the &lt;Tomcat_Home&gt;\common\endorsed directory, where
&lt;Tomcat_Home&gt; is where the Tomcat application server is installed.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-11" class="faqTitle">11. Issues running Applets with XSLTC in Web Browsers with JAVA Plug-in (JRE 1.4)</h3>
<div class="faqQuestion">I got javax.xml.transform.TransformerException running my applet which uses XSLTC in JRE 1.4.</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="applet">‌</a>
</p>
<p>To overwrite an older version of Xalan Java; packaged with JRE 1.4 or higher you can add a newer
xalan.jar and serializer.jar to the &lt;jre-home&gt;\lib\endorsed directory. Read the FAQ about
<a href="#jdk14">Issues running
Xalan-Java on JDK/JRE 1.4 or higer</a>. If there is a META-INF/services/javax.xml.transform.TransformerFactory
file in xalan.jar (as there is in the Xalan Java distributions), then the TransformerFactoryImpl
setting in this file will be used by the JVM during the factory finder lookup procedure.
The TransformerFactoryImpl for the Xalan Java Interpretive processor is the default setting in the
META-INF/services/javax.xml.transform.TransformerFactory file, therefore, you will get an error
when your applet attempts to use the XSLTC implementation.</p>
<p>To work around this problem, you can change the contents of the
META-INF/services/javax.xml.transform.TransformerFactory file in xalan.jar so that it refers to the
transformer factory class implementation for XSLTC, org.apache.xalan.xsltc.trax.TransformerFactoryImpl. </p>
<p>Another solution is to create a jar that contains a META-INF/services/javax.xml.transform.TransformerFactory file
containing the value org.apache.xalan.xsltc.trax.TransformerFactoryImpl. Place the jar in the
&lt;jre-home&gt;\lib\endorsed directory. When you name your jar file, the ASCII code of the first
character should be smaller than the ASCII code of "X" to ensure that your jar will be loaded before
xalan.jar</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-12" class="faqTitle">12. Using the 'signature' file to verify a download</h3>
<div class="faqQuestion">How do I use the "signature" file to verify my download?</div>
<br />
<hr />
<div class="faqAnswer">
<p>For each Xalan-Java download file there is a corresponding signature file.
The signature file for xalan-j_2_0_1.tar.gz, for example, is xalan-j_2_0_1.tar.gz.sig.
</p>
<p>The .sig files are PGP signatures of the actual .zip or .tar.gz
download files. You can use these files to verify the authenticity of the download. You do not
need the .sig file to use the corresponding download file.</p>
<p>To check the authenticity of a Xalan-Java distribution, you need a copy of
PGP which is available in a number of licenses, including some free
non-commercial licenses, either from an mit.edu site or on
the pgp.com site. Once you have a version of PGP installed, you
should be able to 'verify the signature' of the .sig file, which basically verifies that the
corresponding .zip or tar.gz file has not been changed since we signed it.</p>
<p>The PGP key can be found in
<a href="http://svn.apache.org/viewvc/xalan/java/trunk/KEYS">KEYS.</a>
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-13" class="faqTitle">13. Speeding up transformations</h3>
<div class="faqQuestion">What can I do to speed up transformations?</div>
<br />
<hr />
<div class="faqAnswer">
<p>In the ongoing development of Xalan-Java, enhancing performance is
the primary goal of the Xalan-Java team. Here are some preliminary
suggestions for you to keep in mind as you set up your applications:</p>
<ul>
<li>Use a Templates object (with a different Transformers for each transformation) to
perform multiple transformations with the same set of stylesheet instructions (see
<a href="usagepatterns.html#multithreading">Multithreading</a>).
<br />
<br />
</li>
<li>Set up your stylesheets to function efficiently.
<br />
<br />
</li>
<ul>
<li>Don't use "//" (descendant axes) patterns near the root of a large document.
<br />
<br />
</li>
<li>Use xsl:key elements and the key() function as an efficient way to retrieve node sets.
<br />
<br />
</li>
<li>Where possible, use pattern matching rather than xsl:if or xsl:when statements.
<br />
<br />
</li>
<li>xsl:for-each is fast because it does not require pattern matching.
<br />
<br />
</li>
<li>Keep in mind that xsl:sort prevents incremental processing.
<br />
<br />
</li>
<li>When you create variables, <br />
<code>&lt;xsl:variable name="fooElem" select="foo"/&gt;</code>
<br /> is usually faster than
<br />
<code>&lt;xsl:variable name="fooElem"&gt;&lt;xsl:value-of-select="foo"/&gt;&lt;/xsl:variable&gt;</code>
<br />
<br />
</li>
<li>Be careful using the last() function.
<br />
<br />
</li>
<li>The use of index predicates within match patterns can be expensive.
<br />
<br />
</li>
<li>Decoding and encoding is expensive.
<br />
<br />
</li>
</ul>
<li>For the ultimate in server-side scalability, perform transform operations on the client.
For examples, see
<a href="samples.html#appletxmltohtml">appletXMLtoHTML</a> and
<a href="samples.html#get-todo-list">get-todo-list</a>.
</li>
</ul>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-14" class="faqTitle">14. JAXP factory lookup procedure</h3>
<div class="faqQuestion">What is the JAXP factory lookup procedure and does it affect performance?</div>
<br />
<hr />
<div class="faqAnswer">
<p>JAXP uses an ordered lookup procedure to find factory implementations, such as
an implementation of javax.xml.transform.TransformerFactory. For information
on this procedure, refer to Section 3 Plugability in <a href="https://jaxp.java.net/">JAXP 1.3</a>.
</p>
<p>In most cases, Factory classes need only be looked up once for an application, so
performance is not an issue. However, there may be scenarios where the lookup
procedure executes multiple times which could impact performance. In these cases,
users may want to set system properties or populate the jaxp.properties file in order
to shorten the time spent in the lookup procedure.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-15" class="faqTitle">15. Retrieving nodes in the default namespace</h3>
<div class="faqQuestion">XPath isn't retrieving nodes that are in the default namespace I defined. How do I get them?</div>
<br />
<hr />
<div class="faqAnswer">
<p>If you are looking for nodes in a namespace, the XPath expression must include a namespace
prefix that you have mapped to the namespace with an xmlns declaration. If you have declared
a default namespace, it does not have a prefix (see
<a href="http://www.w3.org/TR/xpath.html#node-tests">XPath Node Tests</a>). In order
to construct XPath expressions to retrieve nodes from this namespace, you must add a
namespace declaration that provides a prefix you can include in the XPath expressions.</p>
<p>Suppose, for example, you you want to locate nodes in a default namespace declared as follows:
<br />
<code>xmlns="http://my-namespace"</code>
</p>
<p>Add a namespace declaration with a prefix:
<br />
<code>xmlns:foo="http://my-namespace"</code>
</p>
<p>Then you can use foo: in your XPath expression.</p>
<p>Hint: Avoiding the use of default namespaces will prevent this problem from occuring.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-16" class="faqTitle">16. Setting the parser to be namespace aware</h3>
<div class="faqQuestion">
How do I set my parser to be namespace aware?
</div>
<br />
<hr />
<div class="faqAnswer">
<p>
<a name="namespace-aware">‌</a>
</p>
<p>If you use a TransformerFactory to process a stylesheet Source and generate a Transformer,
the TransformerFactory instructs the SAXParserFactory to set the parser's namespaceAware
property to true. But if you call the parser directly, you may need to set the namespaceAware
property yourself. for example:</p>
<blockquote class="source">
<pre>javax.xml.parsers.SAXParserFactory spFactory =
javax.xml.parsers.SAXParserFactory.newInstance();
spFactory.setNamespaceAware(true);</pre>
</blockquote>
<table class="note">
<tr>
<td class="noteImg">
<img src="resources/note.gif" alt="note" />
</td>
<td class="noteTxt">For more information about setting the namespaceAware property, and SAX2 vs. JAXP default
settings, see <a href="http://people.apache.org/~edwingo/jaxp-faq.html#nsDefaults">JAXP FAQ:
Warning about namespace processing defaults</a>.
</td>
</tr>
</table>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-17" class="faqTitle">17. NoClassDefFound errors</h3>
<div class="faqQuestion">I'm getting a NoClassDefFound error. What has to be on the classpath?</div>
<br />
<hr />
<div class="faqAnswer">
<ol>
<li>xalan.jar, serializer.jar, xml-apis.jar, and xercesImpl.jar -- or the XML parser you are using -- must
always be on the classpath.
<br />
<br />
</li>
<li>To run the samples in the samples subdirectories, xalansamples.jar must be on the
classpath. To run the servlet samples, you must place xalanservlet.war
on a web server with a servlet engine and you must put the javax.servlet and
javax.servlet.http packages on the classpath. These packages
are available via the servlet.jar file found in Apache Tomcat ( see <a href="http://tomcat.apache.org/">The Jakarta Site - Apache Tomcat</a> ).
<br />
<br />
</li>
<li>To run extensions which use the component and script extension elements (including the
samples in samples/extensions), bsf.jar must be on the classpath. To run extensions
implemented in JavaScript, js.jar must also be on the classpath. For information on what
you need to run extensions implemented in other scripting languages, see
<a href="extensions.html#supported-lang">Supported languages</a>.
</li>
</ol>
You can check the correctness of your environment with the
<a href="#environmentcheck">EnvironmentCheck</a> feature.
<p>For more information, see
<a href="getstarted.html#classpath">Setting up the system classpath</a>.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-18" class="faqTitle">18. a "DOM006 Hierarchy request error"</h3>
<div class="faqQuestion">Why do I get a "DOM006 Hierarchy request error" when I try to transform into a DOM Document node?</div>
<br />
<hr />
<div class="faqAnswer">
<p>This error occurs when Xalan-Java tries to add a Node to a Document node
where it isn't allowed. For example, attempting to add non-whitespace text to the DOM Document
node produces this error.</p>
<p>The error can also occur when a Document node is created with the DOMImplementation
createDocument() method, which takes a qualified name as an argument and creates an element
node. If you then pass the returned Document node to Xalan-Java, you
get a "DOM006 Hierarchy request error" when Xalan-Java tries to add a
second element to the Document node. The solution is to either use the DocumentBuilder
newDocument() method to create a Document that does not contain an element node, or use a
DocumentFragment. It should be noted that the DocumentBuilder newDocument() method is
"Non-preferred" according to the JAXP 1.3 documentation.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-19" class="faqTitle">19. Namespace not supported by SAXParser</h3>
<div class="faqQuestion">Why am I getting a "Namespace not supported by SAXParser exception?</div>
<br />
<hr />
<div class="faqAnswer">
<p>We have seen this problem arise for two quite different reasons:</p>
<ul>
<li>SAX1 interfaces are on your classpath in front of the SAX2 interfaces provided with
your XML parser.
<br />
<br />
or
<br />
<br />
</li>
<li>The parser you are using to process a stylesheet Source and generate a Transformer does
not have the namespaceAware property set to true.</li>
</ul>
<p>
<b>SAX1 on the classpath</b>
</p>
<p>SAX1 should not be on your classpath. The SAX1 interfaces and implementations of the SAX1
SAX parser are not namespace aware.</p>
<p>To help diagnose your classpath, you can use the
<a href="#environmentcheck">EnvironmentCheck
utility</a>. If you are running under JDK 1.3, see
<a href="#jdk13">Issues running Xalan-Java on JDK
1.3</a>. If you are running a servlet, make sure the webserver is not placing SAX1 on the
classpath.
</p>
<p>When you create a Transformer, you must use a
<a href="#namespace-aware">namespace-aware</a> parser to parse the stylesheet.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-20" class="faqTitle">20. Missing xsl:version attribute error</h3>
<div class="faqQuestion">I'm getting an error about my stylesheet missing the xsl:version attribute - what's wrong?</div>
<br />
<hr />
<div class="faqAnswer">
<p>There are two common causes for this error.</p>
<ol>
<li>Using the wrong URI for the xsl: prefix will cause this message. URIs, and namespace
URIs in particular, are case sensitive. Ensure the URI for the xsl namespace is
"http://www.w3.org/1999/XSL/Transform".<br />
<br />
</li>
<li>The parser you are using to process a stylesheet Source and generate a Transformer
does not have the namespaceAware property set to true.<br />
When you create a Transformer, you must use a <a href="#namespace-aware">namespace-aware</a> parser to parse the stylesheet.</li>
</ol>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-21" class="faqTitle">21. StackOverflowError with recursive stylesheet</h3>
<div class="faqQuestion">Xalan-Java dies with a java.lang.StackOverflowError when I run a deeply
recursive stylesheet. The same stylesheet worked fine in the past (or on other machines).
What's happening?</div>
<br />
<hr />
<div class="faqAnswer">
<p>That may not be our fault. As of JDK 1.3.x, many Java Virtual Machine publishers reduced
the default size of a thread's call stack from 1MB to 256KB. This allows more threads to
run simultaneously, but it means that each thread is more limited in how deeply its function
calls can be nested.</p>
<p>Some JVMs may offer an option that allows you to raise this limit. For example, in Sun
JDK 1.3.1 you can start JVM with the -Xss1m option to allow each thread to use a full
megabyte. In IBM's JDK you can start with the -Xss1m and -Xoss1m options. Other JVMs
may set this in other ways, or may not allow you to control it at all; check the
documentation on your system for details.</p>
<p>Note too that on some platforms 1MB is an architectural upper limit on the stack size, so
setting -Xss2m (or equivalent) may not allow deeper recursion than -Xss1m.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-22" class="faqTitle">22. OutOfMemoryError processing multiple documents</h3>
<div class="faqQuestion">I get a java.lang.OutOfMemoryError when I try to process multiple documents with the
document() function. What can I do?</div>
<br />
<hr />
<div class="faqAnswer">
<p>As a general rule, Xalan-Java currently caches all of the documents
that you read in with the document() function during a transformation.</p>
<p>If your objective is to transform a series of documents, you can break the process into a
series of transformations. The
<a href="extensionslib.html#pipedocument">PipeDocument</a> extension element
provides one strategy for batching a series of parallel transformations.</p>
<p>Another alternative is to place your document() call in the select attribute of an
xsl:for-each instruction element and use a custom PI (Processing Instruction) to turn off
document caching. Include an XPath expression in your document() call if you do not
need to process the entire document.</p>
<p>Sample stylesheet fragment:</p>
<blockquote class="source">
<pre>
&lt;xsl:template match="doc"&gt;
&lt;xsl:for-each select="document(@href)/bar/zulu"&gt;
&lt;?xalan-doc-cache-off?&gt;
&lt;!-- process each document --&gt;
&lt;xsl:for-each&gt;
&lt;/xsl:template&gt;</pre>
</blockquote>
<table class="note">
<tr>
<td class="noteImg">
<img src="resources/note.gif" alt="note" />
</td>
<td class="noteTxt">PIs do not ordinarily uses namespaces, so "xalan:" is a 'fake' namespace we have
included to indicate that this is not a standard PI.</td>
</tr>
</table>
<p>If you include an XPath expression in your document() call, you can also turn on
<a href="dtm.html#incremental">incremental transform</a> to eliminate the need
to read in the entire document. In fact, you can take advantage of the incremental transform
feature even if you are not turning off document caching.
</p>
<p>You can also increase your JVM heap size with the -Xmx or -mx flag, depending on which JVM
you are using (you can include both flags, and the JVM will ignore the one it doesn't
understand). For example, to give your JVM 64 meg, try
<br />
<code> java -Xmx64m -mx64m
<b>
<i>Class</i>
</b>
</code>
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-23" class="faqTitle">23. File Not Found error</h3>
<div class="faqQuestion">Why do I get 'file not found' when I pass c:\path\filename.txt?</div>
<br />
<hr />
<div class="faqAnswer">
<p>Xalan-Java often requires legal URLs as system identifiers, not local
pathnames (this is partly due to underlying parsers requiring this). A simple (but not always
correct!) way to change a local pathname into a URL in Java 1.1x is:</p>
<blockquote class="source">
<pre>
public static String filenameToURL(String filename)
{
File f = new File(filename);
String tmp = f.getAbsolutePath();
if (File.separatorChar == '\\')
{
tmp = tmp.replace('\\', '/');
}
// Note: gives incorrect results when filename already begins with
file:///
return "file:///" + tmp;
}
</pre>
</blockquote>
<p>For a slightly more detailed example, see org.apache.xml.utils.SystemIDResolver.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-24" class="faqTitle">24. No more DTM IDs are available</h3>
<div class="faqQuestion">What does: "XSLT Error (javax.xml.transform.TransformerException):
org.apache.xml.dtm.DTMException: No more DTM IDs are available" mean?</div>
<br />
<hr />
<div class="faqAnswer">
<p>It means you are probably using a very old version of Xalan or Xalan-Java,
likely the version 2.2D11 which was packaged in JDK1.4. Architectural changes made in
early 2002 should have eliminated this issue for almost all cases.</p>
<p>You should verify the version of Xalan-Java you are using by running
the <a href="#environmentcheck">EnvironmentCheck</a> utility,
and read the FAQ about <a href="#jdk14">Issues running Xalan-Java
on JDK 1.4</a>.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-25" class="faqTitle">25. IllegalAccessError or could not load output_xml.properties on JDK 1.4</h3>
<div class="faqQuestion">Why do I get a "java.lang.IllegalAccessError" or the message
"Could not load the property file 'output_xml.properties'" when I try
to transform using XSLTC or Xalan-Java Interpretive?</div>
<br />
<hr />
<div class="faqAnswer">
<p>These errors may occur if you use JDK 1.4 or later releases.</p>
<p>JRE 1.4 and later releases contain copies of Xalan-Java. In some
cases, the JRE includes only Xalan-Java Interpretive, while in other cases it also
includes XSLTC. Typically, the copy of the processor packaged
with the JRE will be loaded in preference to any copy of Xalan-Java on
your class path.</p>
<p>Beginning with Xalan-Java 2.5, Xalan-Java Interpretive and XSLTC are both
packaged in xalan.jar, and share some of the same classes. If you
are using a version of the JRE that contains Xalan-Java Interpretive, but not
XSLTC, and you try to use XSLTC on your class path,
classes from that version of XSLTC may be loaded along with
classes from the version of Xalan-Java packaged with your JRE.</p>
<p>Because the classes may be from different versions of Xalan-Java, the
results may be unpredictable. In particular, a
<code>java.lang.IllegalAccessError</code> may be thrown, or an
<code>org.apache.xml.utils.WrappedRuntimeException</code> containing
the message: <code>"Could not load the property file
'output_xml.properties' for output method 'xml' (check
CLASSPATH)"</code> may be thrown.</p>
<p>To work around those problems, please read the FAQ entitled
<a href="#jdk14">Issues running Xalan-Java on JDK 1.4</a>.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-26" class="faqTitle">26. Chaining transformations</h3>
<div class="faqQuestion">How do you chain together a series of transformations?</div>
<br />
<hr />
<div class="faqAnswer">
<p>Xalan-Java supports two strategies for chaining together a series of
transformations such that the output of each transformation provides input for the next
transformation.</p>
<ul>
<li>For each transformation in the series, you can set one SAX ContentHandler to process
the input, and another ContentHandler to process the output.
<br />
<br />
</li>
<li>You can also set up a series of parent-child relationships between an XMLReader and
one or more XMLFilters.</li>
</ul>
<p>For the details and links to examples, see
<a href="usagepatterns.html#outasin">Using transformation output as input for
another transformation</a>.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-27" class="faqTitle">27. Stylesheet validation</h3>
<div class="faqQuestion">How do I validate an XSL stylesheet?</div>
<br />
<hr />
<div class="faqAnswer">
<p>An XSL stylesheet is an XML document, so it can have a DOCTYPE and be subject to
validation, right?</p>
<p>The XSLT Recommendation includes a
<a href="http://www.w3.org/TR/xslt#dtd">DTD Fragment
for XSL Stylesheets</a> with some indications of what you need to do to create a
complete DTD for a given stylesheet. Keep in mind that stylesheets can include literal
result elements and produce output that is not valid XML.</p>
<p>You can use the xsl:stylesheet doctype defined in xsl-html40s.dtd for stylesheets that
generate HTML.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-28" class="faqTitle">28. Setting output encoding</h3>
<div class="faqQuestion">Why is the output character encoding I set in the stylesheet not being used?</div>
<br />
<hr />
<div class="faqAnswer">
<p>If you use a character output stream to instantiate the
<a href="apidocs/javax/xml/transform/stream/StreamResult.html">StreamResult</a> object
which holds the transformation output, the Writer uses its own encoding, not the encoding
you specify in the stylesheet.</p>
<p>If you want to use the stylesheet output encoding, do not use StreamResult(java.io.Writer)
to instantiate the holder for the output. Alternatively, you can specify the encoding when
you create a Writer (java.io.OutputStreamWriter). Once the Writer exists, you cannot change
its encoding. If the transformation is run in a servlet, it is possible
that the Writer is coming from the ServletResponse object.
</p>
<p>
If the stylesheet is run using the JAXP APIs and the Transformer's setOutputProperty()
method is invoked, it is possible to set the <b>"encoding"</b> property and
over-ride the value in the stylesheet.
</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-29" class="faqTitle">29. Getting line and column numbers for errors in XML input documents and XSL stylesheets</h3>
<div class="faqQuestion">How do I get line numbers for errors in the XML or XSL input when I am performing a
transformation?</div>
<br />
<hr />
<div class="faqAnswer">
<p>Use or mimic the command-line processor (<a href="apidocs/org/apache/xalan/xslt/Process.html">org.apache.xalan.xslt.Process</a>).
</p>
<p>A
<a href="apidocs/javax/xml/transform/TransformerException.html">TransformerException</a> generally wraps another exception, often a SAXParseException. The command-line processor uses the static
<a href="apidocs/org/apache/xml/utils/DefaultErrorHandler.html">org.apache.xml.utils.DefaultErrorHandler</a> printLocation() method to chase down the exception cause and get a
<a href="apidocs/javax/xml/transform/SourceLocator.html">SourceLocator</a> that can usually report line and column number.
</p>
<p>Suppose you wanted to modify the ValidateXMLInput sample in the samples/Validate
subdirectory to include line and column numbers . All you need to do is call
DefaultErrorHandler.printLocation() in the the Handler internal class error() and warning()
methods. For example, replace</p>
<blockquote class="source">
<pre>public void error (SAXParseException spe)
throws SAXException
{
System.out.println("SAXParseException error: " + spe.getMessage());
}</pre>
</blockquote>
<p>with</p>
<blockquote class="source">
<pre>public void error (SAXParseException spe)
throws SAXException
{
PrintWriter pw = new PrintWriter(System.out, true);
org.apache.xml.utils.DefaultErrorHandler.printLocation(pw, spe);
pw.println("SAXParseException error: " + spe.getMessage());
}</pre>
</blockquote>
<p>You can also replicate code from the printLocation() method to obtain a SourceLocator, and
then use the SourceLocator getLineNumber() and getColumnNumber() methods. The
getRootSourceLocator() method below returns a SourceLocator.</p>
<blockquote class="source">
<pre>
import javax.xml.transform.SourceLocator;
import javax.xml.transform.TransformerException;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.apache.xml.utils.SAXSourceLocator;
import org.apache.xml.utils.WrappedRuntimeException;
....
public static SourceLocator getRootSourceLocator(Throwable exception)
{
SourceLocator locator = null;
Throwable cause = exception;
// Try to find the locator closest to the cause.
do
{
if(cause instanceof SAXParseException)
{
locator = new SAXSourceLocator((SAXParseException)cause);
}
else if (cause instanceof TransformerException)
{
SourceLocator causeLocator =
((TransformerException)cause).getLocator();
if(null != causeLocator)
locator = causeLocator;
}
if(cause instanceof TransformerException)
cause = ((TransformerException)cause).getCause();
else if(cause instanceof WrappedRuntimeException)
cause = ((WrappedRuntimeException)cause).getException();
else if(cause instanceof SAXException)
cause = ((SAXException)cause).getException();
else
cause = null;
}
while(null != cause);
return locator;
}</pre>
</blockquote>
<table class="note">
<tr>
<td class="noteImg">
<img src="resources/note.gif" alt="note" />
</td>
<td class="noteTxt">
<b>Xalan-Java exception handling:</b> The exception architecture
in Xalan-Java and with transforms in general is tricky because of
multiple layers of exception handling, involving movement back and forth between SAX and
Transformer exceptions and across pipes. Xalan-Java often uses a
WrappedRuntimeException to throw over many layers of checked exceptions, in order not to
have every possible checked exception be declared for every function in the stack, which
means it has to catch this exception at the upper levels and unwrap the exception to pass
it on as a TransformerException.
<br />
<br />A JAXP 1.3 TransformerException often wraps another exception. Two of the
TransformerException structures that are frequently used to construct contained exceptions
in JAXP 1.3 do not set the locator. The locator is not set because we don't know the type
of exception that the Throwable argument represents. The solution is to chase up the
contained exceptions to find the root cause, which will usually have a location set for
you. This can be somewhat tricky, as not all the exceptions may be TransformerExceptions.
A good sample is in the DefaultHandler static printLocation() method, which the
Xalan-Java command-line processor uses to report errors. You can also
roll your own functions along the lines of the getRootSourceLocator() example above.
</td>
</tr>
</table>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-30" class="faqTitle">30. Servlet unable to find classes for extension functions/elements</h3>
<div class="faqQuestion">My servlet cannot find classes that implement extension functions or elements. What can I do?</div>
<br />
<hr />
<div class="faqAnswer">
<p>If you install xalan.jar in the webserver's lib directory (e.g., tomcat/lib), as
opposed to the servlet application's lib directory, then the Xalan-Java classes
are loaded by a classloader that does not see the classes in the application's classloader
(i.e., the extension classes, if you placed them there). The Xalan-Java
classes try to load the extension classes using their own classloader, and that attempt
fails.</p>
<p>Workaround: place xalan.jar in the servlet application's lib directory and NOT in the webserver's
lib directory. Another workaround is to place the extension classes also in the webserver's
lib directory, but you generally want to avoid cluttering that directory.</p>
<p>Thanks to Gunnlauger Thor Briem (gthb@dimon.is) for providing this information.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
<h3 id="faq-31" class="faqTitle">31. Translet name doesn't match stylesheet name</h3>
<div class="faqQuestion">My stylesheet is named <code>foo-bar.xsl</code>, but XSLTC
created a translet named <code>foo_bar</code>. Is that a bug?</div>
<br />
<hr />
<div class="faqAnswer">
<p>No. The name of a translet is usually the name of the stylesheet,
the name specified using the <code>translet-name</code> attribute on
the XSLTC <code>TransformerFactory</code> or the name
specified for the translet on the command-line invocation.
However, the name of the translet is also the name of a Java class.
Any character that is not permitted in a class name is replaced with
an underscore.</p>
</div>
<p align="right" size="2">
<a href="#content">(top)</a>
</p>
</div>
<div id="footer">Copyright © 1999-2014 The Apache Software Foundation<br />Apache, Xalan, and the Feather logo are trademarks of The Apache Software Foundation<div class="small">Web Page created on - Thu 2014-05-15</div>
</div>
</body>
</html>