Beyond Discrete E-services: Composing Session-oriented Services in Telecommunications

We distinguish between two broad categories of e-services: discrete services (e.g., add iten to shopping cart, charge a credit card), and session-oriented ones (teleconference, collaborative text chat, streaming video). Discrete services typically have short duration, and cannot respond to external asynchronous events. session-oriented services have longer duration (perhaps hours), and typically can respond to asynchronous events (e.g., the ability to add a new participant to a teleconference). When composing discrete e-services, it usually suffices to use a process model and engine that composes the e-services as relatively independent tasks. But when composing session-oriented e-services, the engine must be able to receive asynchronous events and determine how and whether to impact the active sessions. For example, if a teleconference participant loses his wireless connection, then it might be appropriate to trigger an announcement to some or all of the other participants. In this paper we propose a process model and architecture for flexible composition and execution of discrete and session-oriented services. Unlike previous approaches, our model permits the specification of scripted "event-handling flowcharts" that can be triggered by asynchronous events, and can appropriately impact active sessions. We describe how our framework can support a smart teleconferencing composite e-service.