The Java Platform and XML Portable Code, Portable Data James Duncan Davidson Staff Engineer, Sun Microsystems, Inc

The Java™ Platform and XML

Portable Code, Portable Data

James Duncan DavidsonStaff Engineer, Sun Microsystems, Inc.

Our Overall Goals

• Adopt existing open standards allowing the use of XML by Java™ developers

• Participate in the various XML groups such as W3C and OASIS

• Integrate XML technologies into the Core Platform as appropriate

Our Activities

• W3C Participation• XML Working Group• DOM Working Group• XSL Working Group

• Developing APIs• JAXP• Data Bindings

• Experimenting / Implementing• Project X

Java API for XML Parsers (JAXP)• A thin and lightweight API for

parsing XML documents

• Allows for pluggable parsers

• Allows processing of XML documents using the predominant methods:– Callback Driving (SAX)– Tree Based (DOM)

JAXP Illustration

JAXP

ReferenceParser

OtherParser

User Application

Java Runtime

SAX 1.0

• Simple API for XML

• Accesses Document Serially

• Fast and Lightweight

• Harder to Program

• Sequential Access Only

• API in packages org.xml.sax.*

SAX in Action

SaxParser

UserProvidedHandler

XMLInput

EventsCalled

Using SAX via JAXP

import java.xml.parsers.*;import org.xml.sax.*;

String uri = “http://server/resource.xml”;SAXParserFactory spf;SAXParser parser;HandlerBase handler;

spf = SAXParserFactory.newInstance();spf.setValidating(true);parser = spf.newSAXParser();parser.parse(uri, handler);

// can also parse InputStreams, Files, and SAX// input sources

DOM Level 1

• Document Object Model

• Access XML Documents via a tree structure

• Composed of element nodes and text nodes

• Can “walk” the tree back and forth

• Larger memory requirements

• Package: org.w3c.dom.*

DOM in Action

DocumentBuilder

XMLInput

CreatesTree

Using DOM with JAXP

import java.xml.parsers.*;import org.w3c.dom.*;

String uri = “http://server/resource.xml”;DocumentBuilderFactory dbf;DocumentBuilder builder;Document document;

dbf = DocumentBuilderFactory.newInstance();dbf.setValidating(true);builder = dbf.newDocmentBuilder();document = builder.parse(uri);

// can also parse InputStreams, Files, and SAX// input sources

Namespaces

• Defines a distinct set of XML markup elements

• Associates a URI with a prefix

• Allows multiple vocabularies to be combined in a single XML document

Namespace Example

<?xml version=“1.0”?><book xmlns=“http://server/book” xmlns:isbn=“http://other.gov/isbn”> <title>Cheaper by the Dozen</title> <isbn:number>1568491379</isbn:number></book>

Namespaces in JAXP

// SAX Casespf = SAXParserFactory.newInstance();spf.setValidating(true);spf.setNamespaceAware(true);parser = spf.newSAXParser();parser.parse(uri, handler);

// DOM Casedbf = DocumentBuilderFactory.newInstance();dbf.setValidating(true);dbf.setNamespaceAware(true);builder = dbf.newDocmentBuilder();document = builder.parse(uri);

Using a Compliant Parser• Factories are looked up using

System properties• javax.xml.parsers.SAXParserFactory

• javax.xml.parsers.DocumentBuilderFactory

• Change the property and you can use any parser

JAXP Schedule

• Spec 1.0 Final Release– Available REAL SOON NOW

• Reference Implementation– Final Version REAL SOON NOW

• 1.1– Starting now– Preliminary specs by Summer time

XML Futures

• Participate in spec evolution– XSL/XSLT– Schemas– Xlink / Xpointer– XQL

• Code– JAXP under consideration for Core– Work with Apache– Work with OASIS

Summary

• XML, What it is:– Portable Data

• XML and the Java™ Platform– Portable Code + Portable Data

• JAXP Overview

• Roadmap

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http://java.sun.com/[email protected]

http://www.xml.orghttp://xml.apache.orghttp://www.xml.com

[email protected]@[email protected]