Grid Service Semigroup and Its Workflow Model

Grid service is defined by OGSA as a web service that provides a set of well-defined interfaces and that follows specific conventions. To classify different Grid services and describe their relations, we present Grid Service SemiGroup (GSSG) based on group theory. Moreover, a novel concept, i.e. meta-service, is proposed based on the definition of generating element in cyclic monoid. To meet integration and collaboration demands of distributed and heterogeneous Grid services, some special elements, such as time, resource taxonomy and etc, are introduced to extend basic Petri net for workflow modeling. A new workflow model for GSSG named Grid Service/Resource Net (GSRN) is proposed and presented as well. And some new analysis methods based on graph theory, which complement traditional analysis methods of basic Petri net, are introduced to analyze and evaluate GSRN. The practicability and effectivity of GSRN are demonstrated in an application project.