Contract-Based Generic Programming Mechanism for Dynamic Service Orchestration

The fundamental characteristic of service oriented computing is to bind services dynamically and replace failing service automatically at runtime. The challenge is to provide techniques which can support for programming services in an alterable way. The distinct resources that can provide the same services are logically the identical computational entities. In this perspective, a novel service oriented programming mechanism is proposed through defining a high-level abstraction which involves a generic service signature representing those various resources. The novel service oriented programming mechanism focuses on the business process logic but do not care of the concrete technical implementation of resources, so the development of service oriented applications is more convenient. And the generic services are instantiated under the control of contracts, according to the actual execution status of all candidate resources that are invoked in parallel but not the historical QoS experience. Eventually, the suitable service is bound dynamically since the selection policies are executed according to the run-time context of resources. And how to alternate services that throw exceptions is avoided elaborately. The contract-based generic mechanism divides the service-based application development into two uncorrelated parts, and the concrete implementation of resources is separated from how to provide services or consume services. We also give a case study to illustrate the feasibility of the proposed language mechanism.