For REST-based web services, the restservice.svc service page itself includes additional information. To access this additional information, access the service page's help resource. For example:
Medium security with REST help resource: https://myHostMachine/myWSPWebProject_myHighestSecurityWebService/restservice.svc/help
The help resource presents a list of operations supported by the REST web service. To learn more about a operation, click the POST link in the Method column of the table for the operation you are interested in.
After navigating to a specific operation's help page, the page displays technical information about the operation, including the operation's URL, the HTTP Method, and example request and response messages in both XML and JSON.
The Url is the web address and resource to which requests bound for that specific operation should be sent. The HTTP Method is the HTTP verb that must be used to make the request in order for the web service to accept it. The various example messages provide exact examples with placeholder data that can inform a developer on how to structure request messages made to the operation and what format the response can be expected to take. You can use this information to build an application that produces HTTP web requests using these details.
By default, the response message format (XML or JSON) is determined by the format the request related to the response was sent in. If the request is JSON, the response will be JSON. If the request is XML, the response will be XML. You can override this behavior and change the default response message format if necessary. To do so, open the web service's web.config file and set the automaticFormatSelectionEnabled attribute of the RESTEndpointBehavior behavior to false. Then set the defaultOutgoingResponseFormat attribute to the format you want to use for the response message (XML or JSON).