Non-Local Configuration of Component Interfaces by Constraint Satisfaction

Abstract

Service-oriented computing is the paradigm that utilises services as fundamental elements for developing applications. Service composition, where data consistency becomes especially important, is still a key challenge for service-oriented computing. We maintain that there is one aspect of Web service communication on the data conformance side that has so far escaped the researchers attention. Aggregation of networked services gives rise to long pipelines, or quasi-pipeline structures, where there is a profitable form of inheritance called flow inheritance. In its presence, interface reconciliation ceases to be a local procedure, and hence it requires distributed constraint satisfaction of a special kind. We propose a constraint language for this, and present a solver which implements it. In addition, our approach provides a binding between the language and C++, whereby the assignment to the variables found by the solver is automatically translated into a transformation of C++ code. This makes the C++ Web service context compliant without any further communication. Besides, it uniquely permits a very high degree of flexibility of a C++ coded Web service without making public any part of its source code.