A Constraint Mechanism for Dynamic Evolution of Service Oriented Systems

Service Oriented Architecture (SOA) is a new form of distributed software architecture, which promotes loose-coupling and coarse-granularity. It deploys, composes and calls application components in a distributed way on Internet. The dynamics of Internet environment poses challenge to dynamic service oriented system. The distributive Internet environment requires SOA to be more distributive and self-adaptive, and choreography emphasizes the collaboration between services. Also, more flexible and dynamic software architecture is demanded for service-based software. A strong constraint mechanism which describes architectural limitation of run-time system is needed to make sure the system runs correctly. The main contribution of this paper is a graph grammar based modeling and verification approach for constrained evolution of service-oriented system. System specification described by SOA pattern and structural constraints and their satisfaction checking algorithms are proposed. We have implemented a constrained evolution verification tool that allow us to model runtime SOA, constraints and verify consistency at design-time. Further, a constraint decomposition method towards member services is given for the non-central executable SOA. And we described an adaptive collaboration policy between services to verify consistency when evolution occurs at runtime. A runtime environment's architecture for constraint evolution service oriented system is also proposed.