Session Initiation as a Service

The main focus of this paper is on services involving sessions among dynamically linked objects. It is argued that session initiation in many cases can be generalized and separated from session behaviour. In general, session initiation depends on the state of the actor that is requested to participate in a session. If the actor can handle the requested session in its current state, then it may be initiated. If not, the request may be rejected, queued, forwarded or given other treatment depending on the preferences of the actor. We demonstrate that session initiation and session behaviour can be modeled as separate services using UML collaborations and activity diagrams, and then composed in different ways into complete composite services with dynamic session initiation. Possible solutions for composition of session initiation with service sessions are proposed and discussed.