Mule Issue : More than one JAXBContext - jaxb

Question

We are facing one issue in our Mule Adapter related to JAXB context, needed some opinion on the same
We are using xpath to evaluate some expressions in the choice blocks in our adapter like below for instance,
<choice doc:name="Choice">
<when expression="//env:abc/env:Body/ref:dataelement/ref:/ref:element" evaluator="xpath">
......
</when>
Now, this works perfectly fine in our application but the problem arises when one of other team uses this Adapter as a jar in their application.
When they try to use this adapter, they are getting below error,
Message : More than one object of type class javax.xml.bind.JAXBContext registered but only one expected.
Type : org.mule.api.registry.RegistrationException
Code : MULE_ERROR--2
JavaDoc : http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/registry /RegistrationException.html.
After debugging with the help of loggers etc, we narrowed down to the choice block used above which is causing this particular issue. Also, googled a bit and found one of the posts pointing out the same issue.
Also, to confirm we commented out the choice block having xpath expression and the flow went ahead but broke again where was xpath used in some other way.
https://www.mulesoft.org/jira/browse/MULE-5926
Can anyone please suggest any suitable workaround to resolve this issue?

Answer 1

I agree with you. It is an unresolved issue in Mule.
One solution we have implemented is not define the jaxb context in the config you are providing in the jar file.
Along with the jar file, give instructions to the end application using it, to include the JAXB packages in their JAXB Context object definition.
This way there will be only one JAXB context and it will work smoothly.
Hope this helps.

Answer 2

This is a bit late however the solution that worked was
<mulexml:jaxb-context name=“JAXB_Context“ packageNames=“org.example.test1:org.example.test2“ doc:name=“JAXB Context1“ />
Please note that there must be no space between package names.
Thanks to: http://dominikbial.de/quicktipp-working-with-more-than-one-package-name-in-a-jaxb-context-config-in-mule-esb/

Answer 3

As of now we cannot add more than one JAXBContext in mule. As an alternative you can write your custom transformer.
I implemented something like
public interface MyAppJaxbObj2XmlComponent<I,O> extends
MyAppComponent<I,O>,Callable {
public O marshal(I input) throws Exception;
}
Abstart transformer
public abstract class AbstractMyAppJaxbObj2XmlComponent<I,O> implements
MyAppJaxbObj2XmlComponent<I,O>{
private Class<I> inputType;
public AbstractMyAppJaxbObj2XmlComponent(){
this.inputType = (Class<I>) new TypeToken<I>(getClass())
{}.getRawType();
}
public AbstractMyAppJaxbObj2XmlComponent(Class<I> type){
this.inputType = type;
}
#Override
public Object onCall(MuleEventContext eventContext) throws Exception {
I input = eventContext.getMessage().getPayload(inputType);
O output = marshal(input);
return output;
}
}
Your flow transformer this will load your needed jaxb during startup.
#Component
public class MyFlowJaxbObj2XmlComponent extends
AbstractMyAppJaxbObj2XmlComponent<RequestPayloadType,String> {
#PostConstruct
public void init() {
//Load your schema during startup
}
}
You can also implement a fluid interface as an alternative for this.