Mule: Using JiBX in Mule

Below I'd like to share my attempt to use JiBX inside of Mule to transform incoming XML message into a domain object and back again on the way out. In short, I created a request and response transformer that extended AbstractTransformer.

To start, I had the following domain objects:

   class Person {
       String firstName
       String lastName 
       Address addresss
   }

   class Address {
       String city
       String state
   }

And a sample XML message where a Person has an Address:

  <person>
    <firstname>George</firstname>
    <lastname>Costanza</lastname>
    <address>
      <city>Queens</city>
      <state>NY</state>
    </address>
  </person>

The binding file I used to test out my transformers:

  <?xml version="1.0" encoding="UTF-8"?>
  <binding>
    <mapping name="person" class="Person">
      <value name="firstname" field="firstName"/>
      <value name="lastname" field="lastName"/>
      <structure name="address" field="address" class="Address">
        <value name="city" field="city" />
        <value name="state" field="state" />
      </structure>
    </mapping>
  </binding>

Ok, now to something more interesting with that out of the way... the transformer to turn an incoming XML message to a Person object to use in my service component. Below is one representation of the transformer in Groovy with the types releated to JiBX declared:

class JibxXmlToObject extends AbstractJibxTransformer {
    protected Object doTransform(Object src, String encoding) throws TransformerException {        
        def transformedObject        
        try {
            Reader reader = new StringReader((String) src)
            IBindingFactory factory = BindingDirectory.getFactory(Class.forName(getTargetClassName()))
            IUnmarshallingContext context = factory.createUnmarshallingContext()
            transformedObject = context.unmarshalDocument(reader)
        }
        catch(e) {
            throw new TransformerException(this, e)
        }
        
        return transformedObject
    }
}

To test out my transformer originally, I originally hard-coded the target class name:

  IBindingFactory factory = BindingDirectory.getFactory(Class.forName("org.prystasj.Person"))

In my Mule configuration, I will be declaring it however. If the transformer was a Java class, I might have to have getters and setters to allow for the target class name to be injected. Below is my declaration of the transformer as a custom transformer:

  <custom-transformer name="XmlToPerson" class="org.prystasj.transformers.JibxXmlToObject">
    <spring:property name="targetClass" value="org.prystasj.Person"/>
  </custom-transformer>

  <file:endpoint name="XmlInboundEndpoint"
                 path="/tmp/input"
                 pollingFrequency="3000"
                 transformer-refs="XmlToPerson"/>

And here are the outgoing side of things, transforming a Person back to XML:

public class JibxObjectToXml extends AbstractJibxTransformer {
    protected Object doTransform(Object src, String encoding) throws TransformerException {
        String xml        
        try {
            def writer = new StringWriter()
            IBindingFactory factory = BindingDirectory.getFactory(Class.forName(getTargetClassName()))
            IMarshallingContext context = factory.createMarshallingContext()
            context.marshalDocument(src, encoding, null, writer)
            xml = writer.toString()
        } catch(e) {
            throw new TransformerException(this, e)
        }
        
        return xml
    }
}

And the corresponding Mule configuration:

  <custom-transformer name="PersonToXml" class="org.prystasj.transformers.JibxObjectToXml">
    <spring:property name="targetClass" value="org.prystasj.Person"/>
  </custom-transformer>

  <file:endpoint name="XmlOutboundEndpoint"
                 path="/tmp/output"
                 pollingFrequency="3000"
                 responseTransformer-refs="PersonToXml"/>

Putting the pieces together with a service definition, this example would take a Person in XML and echo it back out in XML after performing both transforms:

  <model name="XmlPersonModel">
    <service name="XmlInputService">
      <inbound>
        <file:inbound-endpoint ref="XmlInboundEndpoint"/>
      </inbound>
      <echo-component/>
      <outbound>
        <pass-through-router>
          <file:outbound-endpoint ref="XmlOutboundEndpoint"/>
        </pass-through-router>
      </outbound>
    </service>
  </model>

A more useful service component could be used to manipulate the incoming person in some way.