Study of the extension to BPEL4Grid for grid service composition

Composing distributed trivial grid services into composite and more powerful services is an effective way to realize grid resource sharing and function reuse. BPEL4Grid is a grid-compliant workflow engine which supports for WSRF standard and GSI mechanism. But BPEL4Grid has some limitations such as its static workflow model and lack of task migration when target service is invalid. Aiming to resolve previous problem, the extension of BPEL4Grid which supports abstract process definition is proposed. Base on the extended BPEL4Grid, an improvement to ActiveBPEL was presented. A QoS-based service evaluation model is described. The experiment indicates that the system is more adaptive with grid´s dynamic characteristic.