Logical connections (bindings)

In a logical connection (also known as a binding from the viewpoint of the client), the client is aware of how to reach an AppServer that provides a specific application service, but it has no awareness of and maintains no persistent connection to any specific AppServer instance. Instead, using its knowledge of how to reach potential AppServers that provide the specified application service, the client invokes remote procedures and user-defined functions for execution on any appropriate AppServer that is available.

A logical connection really represents a binding between the client session and the application service itself, and OpenEdge determines the specific AppServer resource to execute each remote request. Thus, depending on the number of AppServers and agents available to support logical connections to a given application service, many client requests can be executed in parallel.

Clearly, there is no way for an AppServer involved in a logical connection to maintain context between requests for a specific client session because no AppServer is ever aware of the client whose request it services until the moment it receives the request. However, logical connections provide maximum availability of AppServer resources for multiple client sessions and they therefore more readily scale for larger numbers of client requests.

Only one operating mode supports logical connections: State-free. The state-free operating mode and its logical connections support an application service session model known as session-free.

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