Many web services involve a request to create a new persistent object or make an update to an existing persistent object. In order to do these kinds of operation, the application will need input from the client.
A RESTful web service will generally accept input (and produce output) in the form of JSON documents. For more information on JSON, see the Reading JSON documents recipe in Chapter 8, Input/Output, Physical Format, and Logical Layout
How can we parse JSON inputs from web clients? What's an easy way to validate the input?