A rigorous approach to orchestrating grid services

Although conceived for web services, it is shown how Bpel (Business Process Execution Language) can be used to orchestrate a collection of grid services. This is achieved using the technique of Cress (Communication Representation Employing Systematic Specification) to describe the composition of grid services. Cress descriptions are automatically translated into Lotos (Language Of Temporal Ordering Specification), allowing systematic checks for interoperability and logical errors prior to implementation. Mustard (Multiple-Use Scenario Test and Refusal Description) is used to validate the generated specification against use case scenarios. The same Cress descriptions are then automatically converted into Bpel/Wsdl code for practical realisation of the composed services. Grid services are executed by Globus Toolkit 4, while their orchestration is supported by the ActiveBpel engine. The Mustard scenarios are used again to evaluate the implementation. The overall approach therefore supports rigorous development and automated creation of orchestrated grid services.