Release 10.1A: OpenEdge Application Server:
Developing AppServer Applications

Managing stateless and state-free connection context

On a state-reset or state-aware AppServer, all remote procedures executed over the same connection run in the same AppServer agent. The state-aware AppServer session is dedicated to the client connection and its state at the initiation of a client request is exactly as it was when the previous request on the client connection finished.

Stateless AppServer sessions generally require more complex management than sessions on a state-reset or state-aware AppServer. The trade-off is potentially higher throughput for the effort. Because any AppServer agent in a stateless AppServer pool can handle any remote procedure request for any unbound connection, the context created by one remote procedure request is generally unavailable to the next request in the connection sequence. To help you manage context in a stateless environment, the AppServer provides the following mechanisms:

SERVER-CONNECTION-CONTEXT attribute.
SERVER-CONNECTION-ID attribute.
SERVER-CONNECTION-BOUND-REQUEST and SERVER-CONNECTION-BOUND attributes.

For state-free logical connections (bindings), the only practical way to manage context for a client session is for the application service to rely on a context database. In state-free bindings, a client request can be executed, not only on any agent of an AppServer, but on any one of many AppServers that support the application service. Because none of the context management attributes provided for stateless operating mode work in state-free mode (except for the SERVER-CONNECTION-BOUND attribute), the context database must:

Be shared by all AppServer instances that support the application service.
Use an entirely application-defined means to identify and distinguish client sessions that use the application service and to key the context database for this purpose.

Together with this context database, you can use the Activate and Deactivate configuration procedures to restore context for every client request or provide the necessary context database management solely within the context of remote requests.

Other than the "Using the SERVER-CONNECTION-BOUND attribute" section, most of the remaining information on context management applies only to AppServers running in stateless operating mode.