OpenEdge REST applications communicate with an AppServer running the ABL business logic required by your application. Note that the REST application WAR file deployed on a Web server can optionally contain other static or dynamic resources (HTML files, graphics files, etc.).

For OpenEdge REST applications, an AppServer running in the state-free operating mode is recommended. This mode supports a connectionless and context-free interaction between the REST application on the Web server and the ABL application on the AppServer. By definition, a REST application contains all state information in the request and response messages. No state is saved on the server.

OpenEdge REST applications are designed to act as typical Web applications that transparently pass the Web server's authenticated user-id (in the form of an ABL Client-Principal) and session-id (in the form of a CCID) to the AppServer on each request. The AppServer can access that identity information at any time during the execution of the remote request, including the AppServer Activate and Deactivate procedures.

It is possible, however, to access an AppServer running in the stateless operating mode. However, when a REST application accesses a stateless AppServer it disconnects after each HTTP request. You cannot establish a bound connection between a REST client and a stateless AppServer agent. Without a bound connection, your application cannot use the stateless mode's CONNECT/DISCONNECT procedures for login sessions, and it cannot use the ABL SESSION system handle's SERVER-CONTEXT-ID or SERVER-CONTEXT-STRING attributes.

Note that AppServer state-reset and state-aware modes are not appropriate for REST applications and are not supported.

For more information about AppServer configuration and operating modes, see OpenEdge Application Server: Administration and OpenEdge Application Server: Developing AppServer Applications.