Rain4Service: An Approach towards Decentralized Web Service Composition

The widespread adoption of service oriented architecture owes its popularity to service composition, where several web services are combined dynamically at runtime. As is evident today, the Internet is evolving towards the ´Future Internet´. In this context, web service composition has to deal with the problems of mobility, fault tolerance, reliability and the ultra large scale of the Future Internet. The practice of composition, the most popular variant of which is service orchestration, is expected to face numerous challenges in the Impending Future Internet. This is mainly because it comprises a central control point. Service choreography is widely viewed as an appropriate remedy to these problems as it has a predominantly decentralized orientation. In this paper, we propose a decentralized framework for the purpose of executing a case oriented workflow that would be ideal for the Future Internet. The services in the framework communicate and co-ordinate amongst each other without involving a centralized orchestrator. Further, we propose a technique that models the behavior of rain drops to achieve decentralized service composition. Based on the principles of message based service choreography, the proposed composition technique aids selection and execution of web services. We show how the model achieves service composition leveraging both static and runtime properties of a service. A runtime SOA test-bed to validate the decentralized framework and the composition technique is developed in JAVA. Validation is done via real web services. Multiple workflows are executed to demonstrate the viability of the model in actual deployment. Through experiments and exploration, the technique is found to outperform similar techniques in literature.