Modeling and Reasoning about Service Behaviors and Their Compositions

Service-oriented systems have recently emerged as context-independent component-based systems. Unlike components, services can be created, invoked, composed, and destroyed at run-time. Consequently, all services need a way of advertising their capabilities to the entities that will use them, and serviceoriented modeling should cater for various kinds of service composition. In this paper, we show how services can be formally described by the resource-aware timed behavioral language REMES, which we extend with service-specific information, such as type, capacity, time-to-serve, etc., as well as boolean constraints on inputs, and output guarantees. Assuming a Hoare-triple model of service correctness, we show how to check it by using the strongest postcondition semantics. To provide means for connecting REMES services, we propose a hierarchical language for service composition, which allows for verifying the latter’s correctness. The approach is applied on an abstracted version of an intelligent shuttle system.