Java and Extensible Stylesheet Language Transformations (XSLT) are very different technologies that complement one another, rather than compete. Java's strengths are portability, its vast collection of standard libraries, and widespread acceptance by most companies. One weakness of Java, however, is in its ability to process text. For instance, Java may not be the best technology for merely converting XML files into another format such as XHTML or Wireless Markup Language (WML). Using Java for such a task requires skilled programmers who understand APIs such as DOM, SAX, or JDOM. For web sites in particular, it is desirable to simplify the page generation process so nonprogrammers can participate.
XSLT is explicitly designed for XML transformations. With XSLT, XML data can be transformed into any other text format, including HTML, XHTML, WML, and even unexpected formats such as Java source code. In terms of complexity and sophistication, XSLT is harder than HTML but easier than Java. This means that page authors can probably learn how to use XSLT successfully but will require assistance from programmers as pages are developed.
XSLT processors are required to interpret and execute the instructions found in XSLT stylesheets. Many of these processors are written in Java, making Java an excellent choice for applications that must interoperate with XML and XSLT. For web sites that utilize XSLT, Java servlets and EJBs are still required to intercept client requests, fetch data from databases, and implement business logic. XSLT may be used to generate each of the XHTML web pages, but this cannot be done without a language like Java acting as the coordinator.
This book explains the most important concepts behind the XSLT markup language but is not a comprehensive reference on that subject. Instead, the focus is on interoperability with Java, with particular emphasis on servlets and web applications. Every concept is backed by working examples, all of which work on widely available, free tools.
