DOSUG XML Beans overview by Om Sivanesian

XMLBeans
- Accessing XML by binding it to Java types.

XMLBeans
Introduction
XMLBeans Architecture
Compiling XML Schema
Conversions & Validation
XmlCursor
Competing Technologies
Sample Code
Questions

Introduction to XMLBeans
Utilizes the full power of XML in Java
Maps the features of XML Schema to Java Types.
Underlying XML Store allows full access to the entire XML infoset when needed
Generated Java Classes allow Java-friendly access to XML
David Bau started it in BEA and was donated to Apache.

Advantages of XMLBeans
Full XML Schema Support
Full XML Infoset Access
Open technology
Enterprise Standard XML Technology
Make XML Schema easy to use

Important APIs of XMLBeans
XmlObject
Super-most type of the generated interfaces/ classes
XmlCursor
Represents a postion in the XML & provides low-level access to the XML Infoset
SchemaType
Provides a full Schema Object Model

XMLBeans Architecture XML Schema Schema compilation extends XML Schema Binaries Generated classes Application XmlBeans jar SchemaType XMLObject XML API XMLCursor

XMLBeans Architecture (contd.) XML Doc XML Store Validation Parse & Load Reads/ Updates SchemaType XMLObject XML API XMLCursor

Schema Compilation XML Schema Schema Validation Schema Object Model Generated Interfaces/Classes Schema Binaries (.xsb) Compiled Interfaces/Classes XML Types jar Built-in Schema Types

XMLBeans Generated Classes
Schema’s targetNamespace becomes package name
Global elements and types become top-level classes
Anonymous types become inner classes
Local elements and attributes become properties
Simple type properties have both Java and XML set/get

XML To Java Conversions
A Document Interface represents the XML
Use its Factory to parse the XML
From the Document Object get the root object.
Access other information using the getters.
Use the validate() method of the Document Object to check for validity.

Java To XML Conversions
Create a new instance of the Document using its Factory.
From the Document create the Root Object.
Assign values and other objects to it.
The toString() method of the Document gives the XML.
Use the validate() method of the Document Object to check for validity.

XML Cursor
A different way to work with XML
A location in an XML Instance not a Node
Lighter weight than Node based model
Fewer Objects = Less Memory, Less Garbage Collection
Access to full XML Infoset (comments, PIs, whitespace)
Similar to moving a cursor through a text document
<Basket>
<Item>
<Category>First</Category>
</Item>
</Basket>
XmlCursor’s programming model is token based.

XML Tokens
STARTDOC
ENDDOC
START
END
TEXT
ATTR
NAMESPACE
COMMENT
PROCINST

Uses of XmlCursor
XmlToken’s newCursor() gives an XmlCursor
Navigation
Many methods are provided to navigate.
e.g:
aCursor.toParent();
aCursor.toFirstChild();
aCursor.toNextChar();
aCursor.toNextAttribute();
aCursor.toNextSibling();

Uses of XmlCursor (contd.)
To add new elements
Use toNextToken() to go past the STARTDOC token.
Use beginElement(elementName, namespace) to create a new element.
Use insertChars(“value”) to create a text value.
Using XPath to obtain data.
selectPath(aXPath) method returns selections.
Use toNextSelection() to iterate through the selections.

XMLBeans Tools
inst2xsd (Instance to Schema Tool)
Generates XML schema from XML instance files.
scomp (Schema Compiler)
Compiles a schema into XMLBeans classes and metadata.
scopy (Schema Copier)
Copies the XML schema at the specified URL to the specified file.
sdownload (Schema Downloader)
Maintains "xsdownload.xml," an index of locally downloaded XSD files. URLs that are specified are downloaded if they aren't already cached. If no files or URLs are specified, all indexed files are relevant.
sfactor (Schema Factoring Tool)
Factors redundant definitions out of a set of schemas and uses imports instead.
svalidate (Streaming Instance Validator )
Validates a schema definition and instances within the schema.
validate (Instance Validator )
Validates an instance against a schema.
xmlbean Ant task
Compiles a set of XSD and/or WSDL files into XMLBeans types.

Competing Technologies
JAXB
Betwixt
Castor
Zeus
JaxME

Resources
http://dev2dev.bea.com/pub/a/2004/05/ryan_xml.html By Scott Ryan
http://xmlbeans.apache.org/ Documentation & Resources

Sample Code

Questions

DOSUG XML Beans overview by Om Sivanesian

by Matthew McCullough on Feb 12, 2008

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DOSUG XML Beans overview by Om Sivanesian — Presentation Transcript