Instance-based web services composition and verification

Web services composition and verification are very important techniques of Service-Oriented Architecture (SOA). The composite web services are often created at design time and based on functional and non-functional (Quality of Service - QoS) properties. However, the values of QoS properties also depend on each specific instance of web service at runtime (instance-based). Consequently, when we execute the composite web service in the real systems, it may not be accurate with the QoS constraints. Another type of constraint that affects on the web services composition is the constraint on the execution order of component web services in a composite web service. This type of constraint is so-called temporal relation constraint. In this work, we propose a novel web services composition and verification method that is instance-based web services composition and verification. In addition, this study also proposes a new technique which combines all kinds of constraints: hard constraint (functional constraint), soft constraint (QoS constraint) and temporal relation constraint. Our approach has been evaluated on real-world case studies, and has shown promising results.