The statelessness constraint helps services to be more scalable and reliable. Statelessness, in the REST context, means that all the client requests to the server carry all the information as explicit (stated), so that the server understands the requests, treats them as independent, and those client requests keep the server independent of any stored contexts. Keeping the session state within the client is important to manage this constraint in the services.
The following diagram shows the Service Consumer (client) and the Service States are independent and managed within the client and server respectively:
Statelessness ...
