Should JSON RESTful web services use data contract
This is actually a design question. I'm wondering if Spring3.0 REST web services that carries JSON payload provide some kind of data contract similar to traditional web services which follows contract-first design. I know that JSON has schema similar to XSD but where does it fits in spring ? Background: I consider using json as the payload of a client server architecture project where the client is .NET based application and data contract should provide a way to handle multiple versions of the client. The client should be able to post data structures to the server. Or maybe I should take a schema-less approach and use "Simple Data Binding" which is similar to XmlAnyElement?
Answer
The "contract" with "regular" web-services is defined in WSDL files (which include XSDs). With RESTful services these files are called WADL. And spring-mvc does not have support for generating WADLs. (JAX-RS implementations have).
But even if if did, RESTful services are considered more "dynamic" and they don't need to be fixed like that. For example take a look at Facebook's and twitter's REST APIs. They don't provide WADLs or JSON schemas. They provide some free-form documentation of their services. That should be sufficient.