You can use any development tool you wish to develop XSQL pages, but Oracle JDe-
veloper offers some advantages. It is a development environment for building all types
of Java and Java 2 Enterprise Edition (J2EE) applications with great support for XML.
It highlights your text for you, provides easy lookup of Java classes, and checks the
syntax of your XML and XSLT documents. In addition, you get the project manage-
ment capabilities found in most development environments.
Because XSQL pages are also XML documents, the XML syntax checking will keep
your documents well formed. JDeveloper also provides specific support for XSQL
page development. It will perform XSQL-specific syntax checking and will interac-
tively execute your code. When you get into the development of action handlers and
serializers later in the book, you can use it to interactively debug your Java code.
The approach of this book is to be a development tool agnostic. All of the various
types of filesJava, XSLT, and XSQLare all text files that can be developed with any
text editor. This said, JDeveloper is tuned for XSQL page development. If you havent
already found a development environment that you like, JDeveloper is an obvious and
Introduction to XML
Now that you have an overview of the XSQL architecture, it is time to explore the nitty-
gritty of XSQL. As with any language, you also need to know a bit about the syntax.
Because all XSQL documents are also XML documents, the syntax is actually defined
by XML. XSLT is also an XML-based language, so the same is true for it. This means
that you need to learn a bit of the basics of XML.
XML is a very simple language. Its power lies partly in this simplicity. With XML,
you have an easy, industry-standard way to package data. Because XML parsers
are prevalent, anyone can parse your XML document and get at your data. Most
important, you can design exactly how you want your data structured. Here, you are
going to learn the basics of XML. Our aim is to educate you on the structure of XML
The Role of XML
XML is a metalanguage that allows you to define your own markup languages. It is a
project of the World Wide Web Consortium (W3C) and is an open standard. An XML
document looks a lot like an HTML page, but they serve different purposes. Whereas
HTML tells a Web browser how to present data, XML is about structuring data.
XML is best understood as a child of Standard Generalized Markup Language
(SGML). SGML is also the parent of HTML, so XML and HTML can be considered
cousins, and SGML can be considered the mother tongue. SGML has been in use since
the mid-1980s as a way to describe and organize complex documents. Among other
Introducing Oracle XSQL
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