XML Parser for Java is a validating XML parser and processor written in 100%
pure Java. It is a library for parsing and generating XML documents. This
parser easily enables an application to read and write XML data. Version 4.3.0
and above incorporate support for the following:

- Extensible Markup Language (XML) 1.0, Third Edition Recommendation
- Namespaces in XML Recommendation
- Extensible Markup Language (XML) 1.1 Recommendation, excluding support for
  normalization checking
- Namespaces in XML 1.1 Recommendation
- Experimental implementation of XML Inclusions (XInclude) 1.0 Working Draft
  (November 2003) in Last Call, excluding support for XPointer
- W3C XML Schema 1.0 Structures and Datatypes Recommendations
- OASIS XML Catalogs
- SAX 1.0 and 2.0.1
- DOM Level 1, DOM Level 2, and an experimental implementation of the DOM Level
  3 Core and Load/Save Proposed Recommendations
- JAXP 1.2
- The XML Schema API, which provides access to the post-schema validation
  "infoset" (PSVI)
- Use of the "Xerces Native Interface" API throughout the product, allowing
  unprecedented customizing. 

WWW: http://www.alphaworks.ibm.com/tech/xml4j/