PSM approach to Web service composition

In this paper we describe a PSM based initiative towards the dynamic composition of Web services, which is achieved by assembling independently deployed components, pluggable in any context that requires its functionality. The ideas used in our approach based on the Unified-Solving Method development Language (UPML), and CBSE research, adapting and extending them to meet the requirements of component composition. The PSM-based composition count with three main features that distinguish our approach from other works in the field. First, it uses a zero-modification composition policy, which enables the construction of application systems out of existing components independently developed in various domains, without any modification of components. Second, it uses a composition mechanism based on mediators and pipe structures. Mediators allow overcoming compositional mismatches without modifying the code of components, preserving its black box and reusability features. Pipes supply a unified pathway that communicates components or mediators with each other transporting the effects of services. Finally, it makes use of a simple Composition Description Language (CDL), which is intended as a mechanism to depict the internal connection between components representing its physical links. The main functionalities of PSM-based composition are illustrated by means of a scenario involving a book price currency conversion