Can Castor handle class generation from multiple XSDs importing from a base XSD?

Question

I have several XSDs that reuse the same entities. For example, both the XSDs for the ProductPurchaseRequest.xsd and ProductQuoteRequest.xsd both have a <product> tag in them to describe the product in question. For this reason I created a Product.xsd file to define the <product> tag and both ProductPurchaseRequest.xsd and ProductQuoteRequest.xsd import the Product.xsd with a `.

I would like to use Castor to generate Java classes from theses XSDs, and for both of them to use the same class for representing the Product so that I could reuse the same logic for mapping them to our model's ProductModel class.

Can Castor do this? If so, what would be the Ant task syntax for it. If not, would perhaps JAXB be a better alternative?

Answer 1

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB 2 (JSR-222) expert group.

Can Castor do this? If so, what would be the Ant task syntax for it. If not, would perhaps JAXB be a better alternative?

Below is an example of how this could be done using JAXB:

Product

<?xml version="1.0" encoding="UTF-8"?>
<schema 
    xmlns="http://www.w3.org/2001/XMLSchema" 
    targetNamespace="http://www.example.org/Product" 
    xmlns:tns="http://www.example.org/Product" 
    elementFormDefault="qualified">
    <element name="product">
        <complexType>
            <sequence>
                <element name="id" type="string"/>
                <element name="name" type="string"/>
            </sequence>
        </complexType>
    </element>
</schema>

Since multiple XML schemas import Product.xsd we can leverage episode files so that the classes corresponding to Product.xsd are only generated once.

xjc -d out -episode product.episode Product.xsd

ProductPurchaseRequest.xsd

Below is an example of an XML schema that imports Product.xsd:

<?xml version="1.0" encoding="UTF-8"?>
<schema 
    xmlns="http://www.w3.org/2001/XMLSchema" 
    targetNamespace="http://www.example.org/ProductPurchaseRequest" 
    xmlns:tns="http://www.example.org/ProductPurchaseRequest"
    xmlns:prod="http://www.example.org/Product" 
    elementFormDefault="qualified">
    <import namespace="http://www.example.org/Product" schemaLocation="Product.xsd"/>
    <element name="purchase-request">
        <complexType>
            <sequence>
                <element ref="prod:product" maxOccurs="unbounded"/>
            </sequence>
        </complexType>
    </element>
</schema>

When we generate classes from this XML schema we will reference the episode file we created when we generated Java classes from Product.xsd.

xjc -d out ProductPurchaseRequest.xsd -extension -b product.episode

ProductQuoteRequest.xsd

Below is another example of an XML schema that imports Product.xsd:

<?xml version="1.0" encoding="UTF-8"?>
<schema 
    xmlns="http://www.w3.org/2001/XMLSchema" 
    targetNamespace="http://www.example.org/ProductQuoteRequest" 
    xmlns:tns="http://www.example.org/ProductQuoteRequest" 
    xmlns:prod="http://www.example.org/Product" 
    elementFormDefault="qualified">
    <import namespace="http://www.example.org/Product" schemaLocation="Product.xsd"/>
    <element name="quote">
        <complexType>
            <sequence>
                <element ref="prod:product"/>
            </sequence>
        </complexType>
    </element>
</schema>

Again when we generate classes from this XML schema we will reference the episode file we created when we generated Java classes from Product.xsd.

xjc -d out ProductQuoteRequest.xsd -extension -b product.episode

For More Information

• http://weblogs.java.net/blog/kohsuke/archive/2006/09/separate_compil.html

Answer 2

So I was able to get the whole thing working using the JAXB reference implementation. The trick was to realise that the download from JAXB site is a downloader and not the actual libraries! Double-click to accept the licence and the libraries will download locally. Created a test folder (JAXB_TEST) and copied all the downloaded .jars to a lib subfolder. I put all my XSDs in XSD subfolder. After that I ran the following Ant build.xml file.

<?xml version="1.0"?>
<project name="jaxb_test" basedir="." default="package" >

    <taskdef name="xjc" classname="com.sun.tools.xjc.XJCTask">
        <classpath>
            <fileset dir="./lib" includes="*.jar" />
        </classpath>
    </taskdef>

    <target name="generate">
        <delete dir="./gen-src" />
        <mkdir dir="./gen-src" />

        <xjc destdir="./gen-src" language="XMLSCHEMA" package="com.mmm" >
            <schema dir="./xsd" includes="EPC*.xsd" />
        </xjc>      
    </target>

    <target name="compile" depends="generate" >
        <delete dir="./bin" />
        <mkdir dir="./bin" />

        <javac srcdir="./gen-src" destdir="./bin" includeantruntime="false" />
    </target>

    <target name="package" depends="compile" >
        <delete dir="./dist" />
        <mkdir dir="./dist" />
        <jar destfile="./dist/jaxb-gen.jar" basedir="./bin" />
    </target>   


</project>

The only problem I had was that I had an xsd with a root tag called <product> that anonymous extended the Product type to add a version attribute (which I always like to have on my root tag's) which was causing a name conflict for JAXB. So instead, I turned the anonymous type into a named type (i.e. TopLevelProduct) and set the root to that type and JAXB was happy with that.