| Service-based systems (SBS), which are based on Service-Oriented Architecture, are rapidly becoming popular for distributed applications. In a SBS, various organizations in different domains provide various capabilities in the form of services to their users. Service discovery, which is an important required function for SBS, affects the performance of SBS, especially in pervasive computing environments. A pervasive computing environment is heterogeneous with resource-rich and resource-constrained computing devices. In such an environment, the situation, including available service resources, users' preferences and the physical environment, changes more dynamically. In order for the discovered services to be more usable, the service-related resource, situational constraints and user preferences need to be taken into account. Due to the inherent dynamism, heterogeneity and network asymmetry in pervasive computing environments, service discovery needs to be efficient and situation-aware. Hence, an efficient approach to situation-aware service discovery in pervasive computing environment is needed. In addition, the performance of service discovery in a dynamic environment is affected by redundant and unnecessary service discovery messages in the network; hence, a mechanism to suppress the redundant and unnecessary service discovery messages while incurring low network overhead and providing more usable services is needed.;In this dissertation, I present an efficient approach to situation-aware service discovery in pervasive computing environments. My approach exploits network asymmetry, efficiently disseminates service discovery messages and incorporates user preferences, resource and situational information during service discovery. In addition, I present my cooperative suppression scheme (CSS) that enhances the performance of my service discovery approach. Essentially, my CSS scheme: (a) processes service requests adaptively, (b) satisfies the service requests and replies in-network as opposed to at endpoints, (c) proactively suppresses redundant service discovery messages, and (d) provides more usable services to users. The CSS scheme greatly improves the efficiency of service discovery.;The performance of my service discovery approach including my CSS scheme is studied using simulations from the perspective of network overhead and time efficiency. The simulation results show that my approach is efficient and significantly reduces the network overhead, and my CSS scheme greatly improves the efficiency of my approach. |
