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Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family. This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building parser components and configurations that is extremely modular and easy to program.
The Apache Xerces2 parser is the reference implementation of XNI but other parser components, configurations, and parsers can be written using the Xerces Native Interface. For complete design and implementation documents, refer to the XNI Manual.
Xerces2 is a fully conforming XML Schema 1.0 processor. A partial experimental implementation of the XML Schema 1.1 Structures and Datatypes Working Drafts (December 2009) and an experimental implementation of the XML Schema Definition Language (XSD): Component Designators (SCD) Candidate Recommendation (January 2010) are provided for evaluation. For more information, refer to the XML Schema page.
Xerces2 also provides a complete implementation of the Document Object Model Level 3 Core and Load/Save W3C Recommendations and provides a complete implementation of the XML Inclusions (XInclude) W3C Recommendation. It also provides support for OASIS XML Catalogs v1.1.
Xerces2 is able to parse documents written according to the XML 1.1 Recommendation, except that it does not yet provide an option to enable normalization checking as described in section 2.13 of this specification. It also handles namespaces according to the XML Namespaces 1.1 Recommendation, and will correctly serialize XML 1.1 documents if the DOM level 3 load/save APIs are in use.
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<!DOCTYPE faqs SYSTEM 'dtd/faqs.dtd'>
<faqs title='General FAQs'>
<faq title="Querying Xerces Version">
<q>How do I find out which Xerces version I am using?</q>
<a> <p>To find out the release version of Xerces, execute the following:
<code>java org.apache.xerces.impl.Version</code>.
</p>
</a>
</faq>
<faq title="JIRA">
<q>How do I use JIRA to report bugs?</q>
<a> <p>
Please refer to the <link idref="jira">Reporting bugs in JIRA</link>.
</p>
</a>
</faq>
<faq title="Jar file changes">
<q>What happened to xerces.jar?</q>
<a>
<p>In order to take advantage of the fact that this parser is
very often used in conjunction with other XML technologies,
such as XSLT processors, which also rely on standard
API's like DOM and SAX, xerces.jar was split into two
jarfiles:
</p>
<ul>
<li><code>xml-apis.jar</code> contains the DOM level 3,
SAX 2.0.2 and the JAXP 1.4 APIs;</li>
<li><code>xercesImpl.jar</code> contains the implementation of
these API's as well as the XNI API.
</li>
</ul>
<p>For backwards compatibility, we have retained the ability
to generate xerces.jar. For instructions, see <link
idref="install">the installation documentation</link>.
</p>
</a>
</faq>
<faq title="Using JAXP 1.4 on JDK 1.4 and above">
<q>How can I use JAXP 1.4 on JDK 1.4 and above?</q>
<a>
<p>
Use the <jump href="http://download.oracle.com/javase/1.4.2/docs/guide/standards/">Endorsed Standards Override Mechanism</jump>
to specify xml-apis.jar and xercesImpl.jar. This will override the version of JAXP in the JDK. A more complete
description is available <jump href="http://xml.apache.org/xalan-j/faq.html#faq-N100EF">here</jump>.
</p>
<p>
The following methods <strong>do not work</strong>:
<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>
</p>
</a>
</faq>
<faq title="ClassCastException using Xerces">
<q>Why do I get a ClassCastException when I use Xerces and WebSphere Application Server?</q>
<a>
<p>
Xerces uses the <code>ObjectFactory</code> class to load some classes dynamically, e.g. the parser configuration.
The <code>ObjectFactory</code> finds the specified implementation class by querying the system property, reading
<code>META-INF/services/factoryId</code> file or using a fallback classname. After the implementation is found, the
<code>ObjectFactory</code> tries to load the file using the context classloader and if it is null, the
<code>ObjectFactory</code> uses the system classloader.
</p>
<p>
If you run Xerces in an environment, such as WebSphere® Application Server, that has multiple classloaders you may
get ClassCastExceptions thrown from Xerces because different classloaders might get involved in loading Xerces classes.
For example, ClassCastExceptions may occur when utility EAR classes that use Xerces load Xerces classes from WAR modules.
</p>
<p>
We suggest you read the <jump href="http://www-106.ibm.com/developerworks/websphere/library/techarticles/0310_searle/searle.html">"Avoiding ClassCastExceptions..."</jump>
article which explains a workaround for this problem. Also you might want to read the
<jump href="http://www-106.ibm.com/developerworks/websphere/library/techarticles/0112_deboer/deboer.html">"J2EE Class Loading Demystified"</jump>
article that explains how multiple classloaders work in WebSphere Application Server.
</p>
</a>
</faq>
<faq title="Xerces XML, HTML and XHTML Serializers">
<q>What should I be using instead of Xerces' XML, HTML or XHTML serializers?
</q>
<a>
<p>
As of the 2.9.0 release Xerces-J began sharing a common serialization codebase with Xalan and now includes <code>serializer.jar</code>
with its distribution for DOM Level 3 serialization support. The entire <code>org.apache.xml.serialize</code> package was
<strong>deprecated</strong> in Xerces 2.9.0. The HTML and XHTML serializers were previously <strong>deprecated</strong> in the
Xerces 2.6.2 release. You can find more details about the rationale for this decision here in the
<jump href="http://marc.theaimsgroup.com/?l=xalan-dev&m=107593381313807&w=2">archives</jump>.
</p>
<p>
If you want to achieve interoperability and avoid using deprecated APIs, you should not be using Xerces serialization code directly.
Instead, the <jump href="http://jcp.org/en/jsr/summary?id=206">JAXP</jump> Transformer API should be used to serialize HTML, XHTML, and SAX. The <jump href="http://www.w3.org/DOM/DOMTR">DOM</jump> Level 3 Load and Save API (or JAXP Transformer API) should be used to serialize DOM.
</p>
<p>Using <jump href="http://www.w3.org/DOM/DOMTR">DOM</jump> Level 3 you can serialize XML as follows:</p>
<source>import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.Document;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;
import org.w3c.dom.ls.LSOutput;
...
DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
DOMImplementationLS impl =
(DOMImplementationLS)registry.getDOMImplementation("LS");
...
LSSerializer writer = impl.createLSSerializer();
LSOutput output = impl.createLSOutput();
output.setByteStream(System.out);
writer.write(document, output);</source>
<p>Using <jump href="http://jcp.org/en/jsr/summary?id=206">JAXP</jump> you can serialize HTML and XHTML as follows:</p>
<source>
// Create an "identity" transformer - copies input to output
Transformer t = TransformerFactory.newInstance().newTransformer();
// for "XHTML" serialization, use the output method "xml"
// and set publicId as shown
t.setOutputProperty(OutputKeys.METHOD, "xml");
t.setOutputProperty(OutputKeys.DOCTYPE_PUBLIC,
"-//W3C//DTD XHTML 1.0 Transitional//EN");
t.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM,
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd");
// For "HTML" serialization, use
t.setOutputProperty(OutputKeys.METHOD, "html");
// Serialize DOM tree
t.transform(new DOMSource(doc), new StreamResult(System.out));</source>
</a>
</faq>
<faq title="Obtaining smaller jars">
<q>I don't need all the features Xerces provides, but I'm
running in an environment where space is at a premium. Is there
anything I can do?
</q>
<a>
<p>
Partially to address this issue, we've recently begun to
distribute compressed jar files instead of our traditionally
uncompressed files. But if you still need a smaller jar, and
don't need things like support for XML Schema or the WML/HTML
DOM implementations that Xerces provides, then look at the
<code>dtdjars</code> target in our
buildfile.
</p>
</a>
</faq>
<faq title='Validation against DTD'>
<q>How do I turn on DTD validation?</q>
<a>
<p>
You can turn validation on and off via methods available
on the SAX2 <code>XMLReader</code> interface. While only the
<code>SAXParser</code> implements the <code>XMLReader</code>
interface, the methods required for turning on validation
are available to both parser classes, DOM and SAX.
<br/>
The code snippet below shows how to turn validation on -- assume
that <ref>parser</ref> is an instance of either
<code>org.apache.xerces.parsers.SAXParser</code> or
<code>org.apache.xerces.parsers.DOMParser</code>.
<br/><br/>
<code>parser.setFeature("http://xml.org/sax/features/validation", true);</code>
</p>
</a>
</faq>
<!--
<faq title='PSVI'>
<q>How do I get access to the PSVI?</q>
<a>
<p>Xerces provides a sample component PSVIWriter that intercepts document
handler events and collects PSVI information. For more information read <link
idref="samples-xni">samples documentation</link> on how to use xni.parser.PSVIParser
and xni.parser.PSVIConfiguration.
</p>
<note>Xerces only produces light-weight PSVI.</note>
</a>
</faq>
-->
<faq title='International Encodings'>
<q>What international encodings are supported by &ParserName;?</q>
<a>
<ul>
<li>UTF-8</li>
<li>UTF-16 Big Endian and Little Endian</li>
<li>UCS-2 (ISO-10646-UCS-2) Big Endian and Little Endian</li>
<li>UCS-4 (ISO-10646-UCS-4) Big Endian and Little Endian</li>
<li>IBM-1208</li>
<li>ISO Latin-1 (ISO-8859-1)</li>
<li>
ISO Latin-2 (ISO-8859-2) [Bosnian, Croatian, Czech,
Hungarian, Polish, Romanian, Serbian (in Latin transcription),
Serbocroatian, Slovak, Slovenian, Upper and Lower Sorbian]
</li>
<li>ISO Latin-3 (ISO-8859-3) [Maltese, Esperanto]</li>
<li>ISO Latin-4 (ISO-8859-4)</li>
<li>ISO Latin Cyrillic (ISO-8859-5)</li>
<li>ISO Latin Arabic (ISO-8859-6)</li>
<li>ISO Latin Greek (ISO-8859-7)</li>
<li>ISO Latin Hebrew (ISO-8859-8)</li>
<li>ISO Latin-5 (ISO-8859-9) [Turkish]</li>
<li>ISO Latin-7 (ISO-8859-13)</li>
<li>ISO Latin-9 (ISO-8859-15)</li>
<li>Extended Unix Code, packed for Japanese (euc-jp, eucjis)</li>
<li>Japanese Shift JIS (shift-jis)</li>
<li>Chinese (big5)</li>
<li>Chinese for PRC (mixed 1/2 byte) (gb2312)</li>
<li>Japanese ISO-2022-JP (iso-2022-jp)</li>
<li>Cyrillic (koi8-r)</li>
<li>Extended Unix Code, packed for Korean (euc-kr)</li>
<li>Russian Unix, Cyrillic (koi8-r)</li>
<li>Windows Thai (cp874)</li>
<li>Latin 1 Windows (cp1252) (and all other cp125? encodings recognized by IANA)</li>
<li>cp858</li>
<li>EBCDIC encodings:</li>
<ul>
<li>EBCDIC US (ebcdic-cp-us)</li>
<li>EBCDIC Canada (ebcdic-cp-ca)</li>
<li>EBCDIC Netherland (ebcdic-cp-nl)</li>
<li>EBCDIC Denmark (ebcdic-cp-dk)</li>
<li>EBCDIC Norway (ebcdic-cp-no)</li>
<li>EBCDIC Finland (ebcdic-cp-fi)</li>
<li>EBCDIC Sweden (ebcdic-cp-se)</li>
<li>EBCDIC Italy (ebcdic-cp-it)</li>
<li>EBCDIC Spain, Latin America (ebcdic-cp-es)</li>
<li>EBCDIC Great Britain (ebcdic-cp-gb)</li>
<li>EBCDIC France (ebcdic-cp-fr)</li>
<li>EBCDIC Hebrew (ebcdic-cp-he)</li>
<li>EBCDIC Switzerland (ebcdic-cp-ch)</li>
<li>EBCDIC Roece (ebcdic-cp-roece)</li>
<li>EBCDIC Yugoslavia (ebcdic-cp-yu)</li>
<li>EBCDIC Iceland (ebcdic-cp-is)</li>
<li>EBCDIC Urdu (ebcdic-cp-ar2)</li>
<li>Latin 0 EBCDIC</li>
<li>EBCDIC Arabic (ebcdic-cp-ar1)</li>
</ul>
</ul>
</a>
</faq>
<faq title='Accessing Documents on the Internet'>
<q>Why is the parser unable to access schema documents or external entities available on the Internet?</q>
<a>
<p>
The parser may not be able to access various external entities or schema documents
(imported, included etc...) available on the Internet, such as the Schema for Schemas
"http://www.w3.org/2001/XMLSchema.xsd" or the schema defining xml:base, xml:lang attributes etc...
"http://www.w3.org/2001/xml.xsd" or any other external entity available on the Internet. There
are various reasons one could experience such a problem.
<br/>
<br/>
One of the reasons could be that your proxy settings do not allow the parser to make
URL connections through a proxy server. To solve this problem, before parsing a document,
the application must set the two system properties: "http.proxyHost" and "http.proxyPort".
Another reason could be due to strict firewall settings that do not allow any URL connection
to be made to the outside web. The problem may also be caused by a server that is offline or
inaccessible on the network, preventing documents hosted by the server from being accessed.
</p>
</a>
</faq>
<faq title='JDK Compatibility'>
<q>What JDK level is required for Xerces?</q>
<a>
<p>
As of version 2.10.0, Xerces requires JDK 1.3 or later to run and also requires JDK 1.3 or
later to build the source code. Starting with the Xerces 2.11.0 release, the XML Schema 1.1
distribution requires JDK 1.4 or later to run and also to build the source code.
</p>
</a>
</faq>
</faqs>
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