Programming WebLogic XML

Introduction and Roadmap

This section describes the contents and organization of this guide—Programming WebLogic XML.

Document Scope and Audience

This document is a resource for software developers who design and develop applications that include XML processing.

The topics in this document are relevant during the design and development phases of a software project. The document also includes topics that are useful in solving application problems that are discovered during test and pre-production phases of a project.

Although this document does include administration and monitoring information useful to developers who want to test their applications in a development environment, the document does not address production-phase administration, monitoring, or performance tuning topics XML topics. For links to WebLogic Server® documentation and resources for these topics, see Related Documentation.

It is assumed that the reader is familiar with Web technologies, XML, XSLT, the Java programming language, and the Servlet and JSP APIs of the J2EE specification. This document emphasizes the value-added features provided by WebLogic Server XML and key information about how to use WebLogic Server features and facilities to get an application that performs XML processing up and running.

Guide to This Document

This document is organized as follows:

This chapter, Introduction and Roadmap, introduces the organization of this guide and the features of WebLogic Server XML.
XML Overview, provides an overview of XML technology and the WebLogic Server XML subsystem.
Developing XML Applications with WebLogic Server, describes how to process XML documents from within a WebLogic Server application using XML APIs and tools. The main processing tasks include parsing an existing XML document, generating a new XML document, and transforming a XML document into another format.
Using the Streaming API for XML (StAX), describes in detail how to use the Streaming API for XML (StAX) in your Java applications to parse and generate an XML document.
Using Advanced XML APIs, describes how to use additional XML APIs to do more advanced tasks, such as performing XPath matching against an XML document.
XML Programming Best Practices, describes some best practices to follow when creating Java applications that process XML documents.
XML Programming Techniques, describes specific programming techniques for tasks such as using message-driven beans and JMS queues with XML documents, and so on.
XML Application Scoping, describes how to configure parsers, transformers, and external entities for a particular Enterprise application.
Administering WebLogic Server XML, describes the Administration Console XML Registry and how to perform XML configuration tasks.
XML Reference, provides pointers to specifications and application programming interfaces supported by the XML software.

Using the WebLogic XML Streaming API (Deprecated), describes how to use the deprecated WebLogic XML Streaming API. The topic is included in this guide for legacy reasons only; you should not use this API for new applications. Instead you should use StAX, described in Using the Streaming API for XML (StAX).

Samples for the XML Developer

In addition to this document, BEA Systems provides a variety of code samples for XML developers. The examples and tutorials illustrate WebLogic Server XML in action, and provide practical instructions on how to perform key XML development tasks.

BEA recommends that you run some or all of the XML examples before programming your own application that processes XML.

XML Examples in the WebLogic Server Distribution

WebLogic Server optionally installs API code examples in WL_HOME\samples\server\examples\src\examples, where WL_HOME is the top-level directory of your WebLogic Server installation. You can start the examples server, and obtain information about the samples and how to run them from the WebLogic Server Start menu.

Additional XML Examples Available for Download

Additional API examples for download at http://dev2dev.bea.com. These examples are distributed as .zip files that you can unzip into an existing WebLogic Server samples directory structure.

You build and run the downloadable examples in the same manner as you would an installed WebLogic Server example. See the download pages of individual examples for more information.

New and Changed XML Features in This Release

For release-specific information, see these sections in WebLogic Server Release Notes:

WebLogic Server Features and Changes lists new, changed, and deprecated features.
WebLogic Server Known and Resolved Issues lists known problems by GA release and service pack, for all WebLogic Server APIs, including XML.

Summary of WebLogic Server XML Features

WebLogic Server consolidates XML technologies applicable to WebLogic Server and XML applications based on WebLogic Server. The WebLogic Server XML subsystem allows customers to use standard parsers, the WebLogic FastParser, XSLT transformers, and DTDs and XML Schemas to process and convert XML files.

The WebLogic Server XML subsystem includes the following features:

XML Document Parsers

WebLogic Server uses, by default, the XML parser that is included in the JDK Version 5.0.

You can also use any other XML parser of your choice by using the Administration Console to configure it in the XML Registry. You can configure a single instance of WebLogic Server to use one parser for a particular application and use another parser for a different application.

For information about parsing XML documents, see Parsing XML Documents.

Difference In Default Parsers Between Versions 8.1 and 9.1 of WebLogic Server

The default parser in Versions 8.1and previous of WebLogic Server was one that was based on Apache's Xerces parser and whose package name started with weblogic.apache.xerces.*. In Version 9.1 of WebLogic Server, this parser has been deprecated. Instead, the default parser is the same one that is shipped in JDK 5.0.

For backward compatibility, the weblogic.apache.xerces.* parser is still available in Version 9.1 of WebLogic Server, although it is deprecated and BEA highly recommends you do not use it since it will not be available in future versions. If, however, you need to temporarily continue using this parser, you must use the Administration Console to configure a parser other than the default for your WebLogic Server instance by updating, or creating a new, XML Registry and setting the default implementation classes for SAX and DOM parser factory interfaces as indicated in the following table:

Parser Factory Interface	Implementation Class
DOM (DocumentBuilderFactory)	weblogic.apache.xerces.jaxp.DocumentBuilderFactoryImpl
SAX (SAXParserFactory)	weblogic.apache.xerces.jaxp.SAXParserFactoryImpl

For information about creating an XML Registry, see Administering WebLogic Server XML.

XML Document Transformer

WebLogic Server uses, by default, the XML transformer that is included in the JDK Version 5.0.

You can also use any other XML transformer of your choice by using the Administration Console to configure it in the XML Registry. You can configure a single instance of WebLogic Server to use one transformer for a particular application and use another transformer for a different application.

For more information about transforming XML documents, see Transforming XML Documents.

Streaming API for XML (StAX) Implementation

WebLogic Server includes an implementation of the Streaming API for XML (StAX).

For more information, see Using the Streaming API for XML (StAX).

WebLogic XPath API

The WebLogic XPath API contains all of the classes required to perform XPath matching against a document represented as a DOM, an XMLInputStream, or an XMLOutputStream.

For more information, see Using the WebLogic XPath API.

JAXP Pluggability Layer Implementation

Java API for XML Processing (JAXP) 1.2 is a Java-standard, parser-independent API for XML. For more information on JAXP, see What Is JAXP?.

Note: WebLogic Server uses the XML Registry, accessed through the Administration Console, to plug in parsers and transformers. This is different from the JAXP 1.2 specification which specifies the use of system properties to plug in parsers and transformers.

Java API for XML Registries Implementation

The Java API for XML Registries (JAXR) API provides a uniform and standard Java API for accessing different kinds of registries, in particular XML registries used in Web Service applications.

For more information, see Using the Java API for XML Registries (JAXR) API.

WebLogic Servlet Attributes

WebLogic Server supports the following special Servlet attributes:

org.xml.sax.HandlerBase
org.xml.sax.helpers.DefaultHandler
org.w3c.dom.Document

Calling the setAttribute (for SAX parsing) and getAttribute (for DOM parsing) methods on a ServletRequest object with the preceding attributes will parse any given XML document.

For more information, see Parsing XML Documents in a Servlet.

WebLogic XSLT JSP Tag Library

The JSP tag library provides a simple tag that enables access to the default XSLT transformer from within a Java Server Page (JSP) running on WebLogic Server. Currently, this tag supports the default XSLT transformer only; you cannot use the tag to transform an XML document from within a JSP using a different transformer.

The JSP tag library is included in xmlx-tags.jar, which is installed when you install your WebLogic Server distribution.

For more information, see Using the JSP Tag to Transform XML Data.

XML Registry For Configuring Parsers and Transformers

The XML Registry simplifies administration and configuration tasks by separating these tasks from the XML application. Use the Administration Console to configure the parsers and transformers for an instance of WebLogic Server.

For more information, see XML Parser and Transformer Configuration Tasks.

XML Registry for Configuring External Entity Resolution

WebLogic XML supports external entity resolution through the XML Registry. For more information, see External Entity Configuration Tasks.

Endorsed Standards Override Mechanism for DOM/SAX: Not Supported

WebLogic Server does not support switching the server's DOM and SAX interfaces using the endorsed standards override mechanism.

An endorsed standard is a Java API defined through a standards process other than the Java Community Process (JCP). For more information, see Endorsed Standards Override Mechanism.

Learning More About XML

To learn more about XML, see the following online courses and tutorials. XML Reference, provides links to additional information.