Pattern for marshalling, unmarshalling objects to multiple formats

[Nathan England]

Hello, I have a question regarding what pattern or approach to use in Java for the following scenario:

In the "real world" I'm using a web API that accepts a REST query, an XML string, or a SOAP message.
However, the question isn't about the service but rather which pattern do I use to marshall a plain Java object into XML, SOAP, JSON, or a URL REST query key/value pairs.
Theoretically, I have just a given POJO, but I want to convert that into different forms (XML, REST style map, SOAP, JSON).

I cannot change the code for the POJO (but they are annotated where I can use JAXB, at least for the XML part). But I need to take a POJO and be able to generate all different formats without changing the base POJO.

Which design pattern or patterns should I investigate to accomplish this task?

[Richard Tookey]

I suspect you need the visitor pattern - http://en.wikipedia.org/wiki/Visitor_pattern .

[Nathan England]

Thanks for the quick response! I'll check that out.