Event-Based Service Coordination

In this paper we tackle the problem of designing and implementing a framework for programming service coordination policies. In particular, we illustrate the design and the prototype implementation of Java Signal Core Layer (JSCL), a coordination middleware for services based on the event notification paradigm. We formally motivate the design choices of the JSCL middleware by exploiting a variant of the π-calculus specifically tailored to deal with event notification and distribution. We demonstrate how service coordination polices can be precisely programmed in JSCL by some simple but illustrative case studies.