XMLBeans
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| Apache XMLBeans | |
| Developer: | Apache Software Foundation |
|---|---|
| Latest release: | 2.2.0 / July 22, 2006 |
| OS: | Cross-platform |
| Use: | XML binding |
| License: | Apache 2.0 Licence |
| Website: | http://xmlbeans.apache.org |
XMLBeans is a Java-to-XML binding framework which is part of the Apache Software Foundation XML project.
Contents |
[edit] Description
XMLBeans is a tool that allows you to access the full power of XML in a Java friendly way. The idea is that you can take advantage of the richness and features of XML and XML Schema and have these features mapped as naturally as possible to the equivalent Java language and typing constructs. XMLBeans uses XML Schema to compile Java interfaces and classes that you can then use to access and modify XML instance data. Using XMLBeans is similar to using any other Java interface/class: you will see methods like getFoo or setFoo, just as you would expect when working with Java. While a major use of XMLBeans is to access your XML instance data with strongly typed Java classes there are also APIs that allow you access to the full XML infoset (XMLBeans keeps XML Infoset fidelity) as well as to allow you to reflect into the XML schema itself through an XML Schema Object model.
[edit] What Makes XMLBeans Different
- Full XML Schema support.
- Full XML Infoset fidelity.
Full XML Schema support: XMLBeans fully supports XML Schema and the corresponding java classes provide constructs for all of the major functionality of XML Schema. This is critical since often you do not have control over the features of XML Schema that you need to work with in Java. Also, XML Schema oriented applications can take full advantage of the power of XML Schema and not have to restrict themselvs to a subset.
Full XML Infoset fidelity: When unmarshalling an XML instance the full XML infoset is kept and is available to the developer. This is critical because that subset of XML is not easily represented in Java. For example, order of the elements or comments might be needed in a particular application.
[edit] Objective
A major objective of XMLBeans has been to be applicable in all non-streaming (in memory) XML programming situations. You should be able to compile your XML Schema into a set of java classes and know that
- you will be able to use XMLBeans for all of the schemas you encounter (even the warped ones) and
- that you will be able to get to the XML at whatever level is necessary - and not have to resort to multiple tools to do this.
[edit] APIs
To accomplish the above objectives, XMLBeans provides three major APIs:
- XmlObject
- XmlCursor
- SchemaType
XmlObject: The java classes that are generated from an XML Schema are all derived from XmlObject. These provide strongly typed getters and setters for each of the elements within the defined XML. Complex types are in turn XmlObjects. For example getCustomer might return a CustomerType (which is an XmlObject). Simple types turn into simple getters and setters with the correct java type. For example getName might return a String.
XmlCursor: From any XmlObject you can get an XmlCursor. This provides efficient, low level access to the XML Infoset. A cursor represents a position in the XML instance. You can move the cursor around the XML instance at any level of granularity you need from individual characters to Tokens.
SchemaType: XMLBeans provides a full XML Schema object model that you can use to reflect on the underlying schema meta information. For example, you might want to generate a sample XML instance for an XML schema or perhaps find the enumerations for an element so that you can display them.
All of this was built with performance in mind. Informal benchmarks and user feedback indicate that XMLBeans is extremely fast.
[edit] Example
An example of a simple XML Schema Definition to describe a country is given below.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.openuri.org/domain/country/v1"
xmlns:tns="http://www.openuri.org/domain/country/v1"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
version="1.0">
<xs:element name="Country" type="tns:Country"/>
<xs:complexType name="Country">
<xs:sequence>
<xs:element name="Name" type="xs:string"/>
<xs:element name="Population" type="xs:int"/>
<xs:element name="Iso" type="tns:Iso"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="Iso">
<xs:annotation><xs:documentation>ISO 3166</xs:documentation></xs:annotation>
<xs:sequence>
<xs:element name="Alpha2" type="tns:IsoAlpha2"/>
<xs:element name="Alpha3" type="tns:IsoAlpha3"/>
<xs:element name="CountryCode" type="tns:IsoCountryCode"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="IsoCountryCode">
<xs:restriction base="xs:int">
<xs:totalDigits value="3"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="IsoAlpha2">
<xs:restriction base="xs:string">
<xs:pattern value="[A-Z]{2}"/>
<xs:whiteSpace value="collapse"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="IsoAlpha3">
<xs:restriction base="xs:string">
<xs:pattern value="[A-Z]{3}"/>
<xs:whiteSpace value="collapse"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
When the schema is compiled into XMLBean classes (e.g., using Ant), it is very easy to create and manipulate XML data that conforms to the schema definition. The following Java code is a simple example that illustrate how an XML document can be created and validated.
import org.openuri.domain.country.v1.Country; import org.openuri.domain.country.v1.Iso;
public class CountrySample { public static void main(String[] args) { Country country = Country. Factory.newInstance(); country.setName("Denmark"); country.setPopulation(5450661); // from wikipedia :-) // print out country XMLBean as XML System.out.println(country.xmlText()); // check if document is valid - will print "Document is invalid" // because required Iso child elment in not in the object System.out.println ("Document is " + (country.validate() ? "valid" : "invalid")); // add child with complex type Iso to make the document valid Iso iso = country.addNewIso(); iso.setAlpha2("DK"); iso.setAlpha3("DNK"); iso.setCountryCode(208); // print out country XMLBean as XML System.out.println(country.xmlText()); // check if document is valid - will print "Document is valid" System.out.println ("Document is " + (country.validate() ? "valid" : "invalid")); } }
[edit] History
David Bau initiated the XMLBeans project while he was working for BEA (he now works for Google). He was the chief designer of the tool, and he led the team that designed and implemented XMLBeans 1.0.
XMLBeans was originally developed as part of the proprietary BEA WebLogic Workshop Framework, but it was obvious from interviews conducted when it was first announced on January 27, 2003, that BEA wanted it to become an open standard. At that time it was not decided which organisation BEA wanted to involve in the standardisation effort. Later that year it was donated to the Apache Software Foundation.
- January 27, 2003: BEA announces XMLBeans as a technology preview.
- September 24, 2003: BEA donates XMLBeans to the Apache Software Foundation where it joins the Apache Incubator Project.
- April 23, 2004: XMLBeans Version 1.0.2 is released. This is the first release from the incubator project.
- June 25, 2004: XMLBeans graduated out of the Apache Incubator Project to become top level project.
- June 30, 2005: XMLBeans Version 2.0 is released.
- November 16, 2005: XMLBeans Version 2.1 is released.
- June 23, 2006: XMLBeans Version 2.2 is released.
[edit] See also
[edit] External links
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| License: Apache License • Website: apache.org | |
