Correlation Patterns in Service-Oriented Architectures

When a service engages in multiple interactions concurrently, it is generally required to correlate incoming messages with messages previously sent or received. Features to deal with this correlation requirement have been incorporated into standards and tools for service implementation, but the supported sets of features are ad hoc as there is a lack of an overarching framework with respect to which their expressiveness can be evaluated. This paper introduces a set of patterns that provide a basis for evaluating languages and protocols for service implementation in terms of their support for correlation. The proposed correlation patterns are grounded in a formal model that views correlation mechanisms as means of grouping atomic message events into conversations and processes. The paper also provides an evaluation of relevant standards in terms of the patterns, specifically WS-Addressing and BPEL, and discusses how these standards have and could continue to evolve to address a wider set of correlation scenarios.