Reliability modeling for SOA systems

Service-oriented architecture (SOA) is a popular paradigm for development of distributed systems by composing the functionality provided by the services exposed on the network. In effect, the services can use functionalities of other services to accomplish their own goals. Although such an architecture provides an elegant solution to simple construction of loosely coupled distributed systems, it also introduces additional concerns. One of the primary concerns in designing a SOA system is the overall system reliability. Since the building blocks are services provided by various third parties, it is often not possible to apply the well established fault removal techniques during the development phases. Therefore, in order to reach desirable system reliability for SOA systems, the focus shifts towards fault prediction and fault tolerance techniques. In this paper an overview of existing reliability modeling techniques for SOA-based systems is given. Furthermore, we present a model for reliability estimation of a service composition using directed acyclic graphs. The model is applied to the service composition based on the orchestration model. A case study for the proposed model is presented by analyzing a simple Web Service composition scenario.