Optimizing QoS-Aware Services Composition for Concurrent Processes in Dynamic Resource-Constrained Environments

QoS-aware service composition intends to integrate services from different providers and maximize the global QoS in order to increase the user´s satisfaction degree while subjecting to dynamic context constraints. Current composition approaches only focus on optimizing a single process to maximize the satisfaction degree for one party. When multiple processes are performed concurrently by their selfish users in a dynamic resource-constrained environment, new issues will arise, i.e., undesirable competition for service resources, extra waiting and frequent change of contexts. To address these issues, this paper aims to optimize QoS-aware services composition for multiple selfish users if the communication among users is allowed. Firstly, we propose an extensional QoS-aware service selection model for each process. Then based on this model, we present fault handling mechanisms before and during the execution of concurrent composite services for concurrent processes based on a multi-issue negotiation protocol among agents, and an adaptive context-aware service re-selection mechanism for adjusting the service execution plan for each running composite service in the dynamic resource-constrained environment. Comparative experiments reveal our approach facilitates to increase the average satisfaction degree, reduce the average waiting time of multiple users, and make the satisfaction degrees among multiple users more evenly distributed in the dynamic resource-constrained environment.