In order to exchange data through a web service, you need to set up a server-side requestor, or 'producer' program, as well as a client-side provider, or 'consumer' program, as explained in the Introduction. The REST-style architecture is stateless, with the client and server sides running separately. They communicate using HTTP protocol, and REST supports messages in JSON, XML, and other formats. The following chapters describe these two different types of COBOL programs.