Is there a standard way to describe the data in JSON format, similar to a WSDL file for SOAP?

Basically, I want to be able to say that few fields have extra restrictions beyond "string" and "integer". For example, field "u开发者_Python百科ser name" is 32 characters or less, "age" must be an integer greater than 21, etc.

Is there some standard way to specify this without the huge overhead of a WSDL file, preferably supported by a ruby gem of some sort?

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There's the jsonschema gem https://github.com/Constellation/ruby-jsonchema

more info http://json-schema.org/