Monitoring WS-Agreement s: An Event Calculus-Based Approach

In this paper, we present a framework that we have developed to support the monitoring of service level agreements. The agreements that can be monitored by this framework are expressed in an extension of WS-Agreement that we propose. The main characteristic of the proposed extension is that it uses an event calculus based language, called EC-Assertion, for the specification of the service guarantee terms in a service level agreement that need to be monitored at runtime. The use of EC-Assertion for specifying service guarantee terms provides a well-defined semantics to the specification of such terms and a formal reasoning framework for assessing their satisfiability. The paper describes also an implementation of the framework and the results of a set of experiments that we have conducted to evaluate it.