Evaluating Contract Compatibility for Service Composition in the SeCO2 Framework

Recently, the Software-as-a-Service (SaaS) model has been increasingly supported, becoming a major part of the new emerging cloud computing paradigms. Although SaaS exists in different forms, supporting and providing SaaS developed based Web services has attracted a large effort from industries and academics because this form of SaaS allows software to be easily composed and integrated to offer new services for customers. Even though various service composition techniques, based on functional and non-functional parameters, have been proposed, the issue of service contract compatibility has been neglected. This issue is of paramount importance in the Web services-based SaaS model because services are provided by different providers, associated with different contracts which are defined by different specifications. This paper proposes techniques for supporting service composers to deal with the heterogeneity of service contracts in service composition. We describe a novel approach for modeling and mapping different service contract specifications, and a set of techniques for evaluating service contract compatibility. Our techniques consider contract terms associated with data and control flows, as well as composition patterns. Illustrating scenarios are proposed to demonstrate the efficiency of our techniques.