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XML Enhancements for Java (XJ) (http://www.alphaworks.ibm.com/tech/xj) are
a set of extensions to Java 1.4 that integrate support for XML, XML Schema
and XPath 1.0 into the language. The advantages of XJ over existing
mechanisms for XML development are:

- Familiarity (for the XML Programmer): XML processing in XJ is consistent
with open XML standards.
- Robustness: XJ programs are strongly typed with respect to XML Schemas.
The XJ compiler can detect errors in uses of XPath expressions and
construction of XML data.
- Easier Maintenance: Since XJ programs are written in terms of XML and
not low-level APIs such as DOM or SAX, they are easier to maintain and
modify if XML Schemas change.
- Performance: Since the compiler is aware of the use of XML in a program,
it can optimize the runtime representation, parsing, and XPath evaluation
of XML.

In XJ, one can import XML schemas just as one does Java classes. All the
element declarations in the XML schema are then available to programmers
as if they were Java classes. Programmers can write inline XPath
expressions on these classes, and the compiler checks them for correctness
with respect to the XML schema. In addition, the compiler performs
optimizations in order to improve the evaluation of XPath expressions. A
programmer may construct new XML documents by writing XML directly inline.
Again, the compiler ensures correctness with respect to the appropriate
schema. By integrating XML and Java, XJ allows programmers to reuse
existing Java libraries in the development of XML code and vice-versa.

XJ is an evolving language, and therefore any comments, criticisms or
praise from developers is most welcome.

Igor Pechtchanski (for the XJ team)

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Igor Pechtchanski
IBM T.J. Watson Research Center
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj)