Decentralized service composition in pervasive computing environments

In a pervasive computing environment, the devices are embedded in the physical world, providing services and interconnected by a communication network. Composition of these services is important issue of pervasive applications which integrate the physical and cyber worlds. Most existing research on service composition in pervasive computing relies on the existence of one or more entities that maintain the global service information. However, such an approach is not always practical due to dynamicity of the environment. In this paper, we propose a fully decentralized approach to service composition. We first model the service composition problem as finding an overlay of the communication network that matches the composition graph. The problem is proved to be NP-complete. We propose an algorithm for the devices to cooperatively construct the requested services through localized interactions. For the purpose of reducing redundant broadcast we propose the service composition backbone built in a fully localized way. We have carried out extensive simulations. to evaluate the performance of our algorithm. Compared with existing pull-based centralized techniques our decentralized service composition algorithm on the service composition backbone is more efficient in terms of response delay and message overhead, while achieving similar quality of composed service.