Path-Based Error Propagation Analysis in Composition of Software Services

摘要

In Service-Oriented Architectures (SOA) composed services provide functionalities with certain non-functional properties that depend on the properties of the basic services. Models that represent dependencies among these properties are necessary to analyze non-functional properties of composed services. In this paper we focus on the reliability of a SOA. Most reliability models for software that is assembled from basic elements (e.g. objects, components or services) assume that the elements are independent, namely they do not take into account the dependencies that may exist between basic elements. We relax this assumption here and propose a reliability model for a SOA that embeds the "error propagation" property. We present a path-based model that generates the possible execution paths within a SOA from a set of scenarios. The reliability of the whole system is then obtained as a combination of the reliability of all generated paths. On the basis of our model, we show on an example that the error propagation analysis may be a key factor for a trustworthy prediction of the reliability of a SOA. Such a reliability model for a SOA may support, during the system development, the allocation of testing effort among services and, at run time, the selection of functionally equivalent services offered by different providers.