Semantic Service Composition and Co-ordination in CASCOM
Thorsten Möller, Heiko Schuldt, Andreas Gerber, Matthias Klusch
Proceedings of the 3rd Healthcare Digital Libraries Workshop (HDL 2005)
Semantic (Web) services allow for a fine-grained description of the functionality of single services and highly facilitate the combination and composition of several services into processes. The traditional workflow and process management approach considers the definition of a process at build-time without taking into account the service instances that are actually available at run-time. Moreover, failures have to be anticipated in order to define appropriate failure handling strategies. In this paper, we present an agent-based approach where process execution is distributed among a set of agents. A dedicated planning component composes semantic services based on the particular goals of an application. In case of failures, the planner is re-invoked in order to define contingency execution strategies. Finally, instance matchmaking is done at run-time by choosing the most appropriate service provider (according to pre-defined quality-of-service constraints). The focus of this paper is on the interaction of planning, matchmaking, and execution of processes (compound services) consisting of invocations of semantic web services. In the EU-funded project CASCOM, these technologies are currently applied to the composition of semantic services from the healthcare domain in order to run individualized applications (processes), thereby providing access to an eHealth digital library of services and data.