Trust-based service composition in multi-domain environments under time constraint

Trust plays a pivotal role in decision support for service-oriented computing networks.Recent advances in service evaluation and selection have provided some preliminary findings on the construction of composite services.However,the great expense of interdomain validations,the dynamic execution time and the subjective requirement for global execution time remain serious obstacles to the trust-based service composition.To solve these issues,this paper proposes a novel service-composition approach,modeling the trust-based service composition as the multi-domain scheduling and assignment problem using the minimum service resources within a certain time constraint.In our approach,each service is designed as an exclusive resource during its execution.By analyzing the required interdomain communications,the number of available services and the aggregated trust value in each domain,the optimal domain can be obtained at each step of service selection.Meanwhile,loop parallelization and predecessor reselection are adopted when the task cannot be completed on schedule.Finally,to raise higher trust value of the composite result,the redundant service resources of the initial composition are further optimized.The experimental results illustrate that the proposed trust-based service-composition approach outperforms traditional ones in both effectiveness and scalability under various time constraints.