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This paper proposes a self-healing approach to handle exceptions in service-based processes and to repair the faulty activities with a model-based approach. In particular, a set of repair actions is defined in the process model, and repairability of the process is assessed by analyzing the process structure and the available repair actions. During execution, when an exception arises, repair plans are generated by taking into account constraints posed by the process structure, dependencies among data, and available repair actions. The paper also describes the main features of the prototype developed to validate the proposed repair approach for composed Web services; the self-healing architecture for repair handling and the experimental results are illustrated

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Web service composition is emerging as an interesting approach to integrate business applications and create intra-organizational business processes. Single Web services are combined to create a complex Web service that will realize the process business logic. Once the process is created, it is executed by an orchestration engine that invokes individual Web services in the correct order. However, Web services composing the workflow sometimes become unavailable during the run-time phase, blocking process execution. This paper describes an architecture that allows the flexible orchestration of business processes. With this approach, Web services composing the process can be automatically substituted with other compatible Web services during process execution. A methodology is defined to evaluate Web service compatibility based on interface matching, in order to select substitutable Web services. Copyright (c) 2005 John Wiley & Sons, Ltd

Failures during web service execution may depend on a wide variety of causes, such as network faults, server crashes, or application-related errors, such as unavailability of a requested web service, errors in the orchestration of choreography of applications, missing data or parameters in an execution flow, or low Quality of Service (QoS). In this paper, we propose a healing architecture able to handle web service faults in a selfhealing way, discussing infrastructural faults and web service and Web application faults. The self-healing architecture manages repair actions, such as substitution of a faulty service or duplication of overloaded services. Implemented prototypes involving QoS in coordinated web services are illustrated and discussed. 1