QoS-Driven Adaptation of BPEL Scenario Execution

BPEL/WSBPEL is the predominant approach for combining individual Web services into integrated business processes, allowing for the specification of their sequence, control flow and data exchanges. BPEL however does not include mechanisms for considering the invoked servicespsila Quality of Service (QoS) parameters and thus BPEL scenarios can neither tailor their execution to the individual userpsilas needs or adapt to the highly dynamic environment of the WEB, where new services may be deployed, old ones withdrawn or existing ones changing their QoS parameters. Moreover, infrastructure failures in the distributed environment of the Web introduce an additional source of failures that must be considered in the context of QoS-aware service execution. In this work we propose a framework for addressing the issues identified above; the framework allows the users to specify the QoS parameters that they require and it undertakes the task of locating and invoking suitable services. Finally, the proposed framework intercepts and resolves faults occurring during service invocation, respecting the QoS restrictions specified by the consumer.