Formal Analysis of Behavioural Equivalence for Trustworthy and Composite Web Services

Trustworthy and composite web services play important roles in service-oriented systems. Web services choreography as one important approach of composing web services describes the global model of service interactions among a set of participants. Bisimilar analysis that checks whether two choreographies are behavioural equivalent is an important verification approach for trustworthy composition. This paper discusses strong and weak bisimilarity of choreographies. Internal and external roles are distinguished from special roles that we hope to verify their observable behaviours. A language named Chor which is based on abstract syntax of WS-CDL is proposed to describe behaviours. In Chor, internal roles and internal activities among them are abstracted for their no effect on externally observable behaviour. A real example is presented to illustrate the usages and benefits of the formal analysis.