Some site have REST API that return responses in two formats : xml and JSON .
Currently I finished basic checks for xml responses of this API .

Idea was simple - validate xml response using existing xsd schema that clear define what should be inside . I use Jersey (— Project Kenai ) for "speaking" with API and SAX to validate responses.

Now I need to do the same for JSON format . First big problem here is that I don't have JSON Schema to validate JSON response . So only way that I see is unmarshall JSON response to POJO hierarchy and then validate it against xsd that I have . But this way also raise up hard questions : I can't find Java classes that allow me to do this automatically . Also I can't find classes that allow me to work with xsd in low level - I mean not just general "tell me if this xml is valid according this xsd" but "tell me if this tag can have such children with such types".

Any ideas , directions or just thoughts are welcome. Maybe somebody can suggest totally different way ? Or somebody can suggest classes that allow to work with xsd on low level ?