Achieving Dependable Composite Services through Two-Level Redundancy

Service composition is a widely accepted method to build service-oriented applications. However, due to the uncertainty of infrastructure environments, service performance and user requests, service composition faces a great challenge to guarantee the dependability of the corresponding composite services. In this chapter, we provide an insightful analysis of the dependability issue of composite services. And we present a solution based on two-level redundancy: component service redundancy and structural redundancy. With component service redundancy, we study how to determine the number of backup services and how to guarantee consistent dependability of a composite service. In addition, structural redundancy aims at further improving dependability at business process level through setting up backup execution paths.