Decoupling Metrics for Services Composition

The decoupling is one of the most important features of service components that make Web services successful in the future. Decoupling metrics can be used to measure and evaluate the decoupling attributes of a distributed service oriented software architecture that has very significant impacts on the understandability, maintainability, reliability, testability, and reusability of software components. The decoupling metrics can also be used as a criterion for selection of existing service components for compositions. Many measurement metrics for decoupling have been proposed, however most measures are not specific for service component decoupling. This paper provides a practical guide for evaluating decoupling between service-oriented components in the service composition such as business process execution language (BEPL). Coupling was originally defined as the measure of the strength of association established by a connection from one module to another. Most of the existing techniques and measuring coupling metrics are classified by procedural programming and object-oriented programming. In this paper we propose a decoupling metrics based on the black-box parameters of service stateness (stateless/stateful), interaction (one-way, two-way), service interface required, service interface provided (supporting/supported interface), invocation modes (sync/async), self-containment (stand-alone/indirect dependent), implicit invocation (blocking/non-blocking), and binding modes (static/dynamic)