Java TM API for XML Processing 1.1

Transcription

1 Java TM API for XML Processing 1.1 James Duncan Davidson Jason Hunter Slide 1

2 JAXP 1.1? Java Community Process initiative JSR ? Feature list:? SAX2.0.? SAX 2 extensions.? DOM Level 2 Core interfaces.? XSLT 1.0? Improved mechanism for factory lookup. Slide 2

3 JAXP 1.1 Expert Group Allaire Apache Software Foundation BEA Systems Inc Cromwell Media Fujitsu Limited IBM Informix Inso Corporation Jason Hunter Lutris Technologies Persistance Software, Inc POET Software Sun Microsystems Slide 3

4 JAXP: Processing APIs for Java User Application JAXP Interfaces Reference Impl Other Impl Slide 4

5 JAXP Description? A lightweight API for parsing XML Documents? Allows for plugable parsers? API for transformation, referred to as TrAX.? Allows for plugable XSLT engines.? Allows processing of XML using:? Callback Driven (SAX)? Tree Based (DOM)? XSL Transformation. Slide 5

6 SAX2.0 API? Simple API for XML? Accesses Documents Serially? Fast and Lightweight? Harder to Program? Sequential Access Only? Supports Namespaces? Org.xml.sax? Org.xml.sax.ext Slide 6

7 SAX 2.0 (Contd) Input Events XML Document Parser Provided Handler Slide 7

8 SAX used via JAXP import java.xml.parsers.* import org.xml.sax.* SAXParserFactory factory = SAXParserFactory.newInstance(); factory.setvalidating(true); SAXParser parser = factory.newsaxparser(); parser.parse(" handler); // can also parse InputStreams, Files, and // SAX input sources. Slide 8

9 SAX ContentHandler import org.xml.sax.* public class MyHandler implements ContentHandler { public void startdocument() throws SAXException { // start processing here. Could store it in a // stack and build your own tree representation // This is the first method invoked } public void enddocument() throws SAXException { // This is the last method invoked on the // handler } public void characters(char[] ch, int start, int end) throws SAXException { } } Slide 9

10 DOM Level 2? Document Object Model? Access XML document via a tree structure? Composed of element nodes and text nodes? Can "walk" the tree back and forth? Larger memory requirements? org.w3c.dom.* Slide 10

11 DOM Level 2 (Contd) Input Creates Tree XML Document Parser Slide 11

12 DOM used via JAXP import java.xml.parsers.* import org.w3c.dom.* DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); factory.setvalidating(true); DocumentBuilder builder = factory.newdocumentbuilder(); Document doc = builder.parse(" // can also parse InputStreams, Files, and // SAX input sources. Slide 12

13 XSLT 1.0? XSL Transformations.? Syntax and semantics for transforming xml documents into other xml documents or any other format.? Expressed as a well-formed xml document.? Recommended Processing Instruction to apply to an xml document? <?xml-stylesheet href="mystyle.css" type="text/css"?> Slide 13

14 XSLT 1.0 (Contd) XML Document Input XSLT Processor Result Resulting XML Document XSL Stylesheet Slide 14

15 XSLT APIs in JAXP (contd)? javax.xml.transform? Defines basic set of interfaces for XSLT processors.? Defines TransformerFactory and Transformer abstract classes that all processors implement.? Defines Templates, Source and Result interfaces.? Templates represent processed transformation instructions. Slide 15

16 XSLT used via JAXP import java.xml.transform.*; Transformer transformer; TransformerFactory factory = TransformerFactory.newInstance(); try { // Create a transformer for a particular stylesheet. transformer = factory.newtransformer( new StreamSource(stylesheet)); // Transform the source xml to System.out. transformer.transform(new StreamSource(sourceId), new StreamResult(System.out)); } catch (Exception e) { // handle error } Slide 16

17 Plugability? Factory lookup is accomplished by? System property? javax.xml.parsers.saxparserfactory? javax.xml.parsers.documentbuilderfactory? javax.xml.transform.transformerfactory? $JAVA_HOME/lib/jaxp.properties file? Jar Services API? META-INF/services/javax.xml.parsers.XXXFactory? Reference Default Slide 17

18 Changing Properties Command Line: java -Djavax.xml.parsers.SAXParserFactory=MyParserFactory MyClass In Code: System.setProperty( "javax.xml.parsers.saxparserfactory", "foo.bar.myparserfactory"); System.setProperty( "javax.xml.parsers.documentbuilderfactory","foo.bar.mydocu mentbuilder"); Slide 18

19 Reference Implementation? Parser and XSLT Engine based on ASF Code? Apache Crimson for XML Parsing? Apache Xalan for XSLT Processing Slide 19

20 Current Status? Final version of the specification and the RI can be obtained by following links from? Feedback aliases? JCP information? Slide 20

21 Q&A Slide 21