XCAT
The most important recent development in Grid systems is the adoption of the Web services model as a basic architecture for Grid services. XCAT is a component framework for building distributed Grid applications and is consistent with this model. XCAT is compliant with the U.S. Department of Energy Common Component Architecture (CCA) with an implementation based on the standard Web services stack, whose layers include discovery, description, messaging, and transport. XCAT leverages the advantages of both the component and Web services world. With XCAT, it is possible for an application programmer to build distributed applications by composing software components running on remote resources. The result is a stateful Web service that represents the executing application instance. XCAT provides a scripting based programming model along with a standard set of services for building applications on the Grid.