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Facilitating Dynamic Adaptation of Workflows Through Flexible Exception Handling
Michael Adams
PhD Final Seminar
Abstract
This research re-examines the fundamental theoretical principles underpinning workflow technologies to derive an approach that moves forward from the production-line paradigm and thereby offers workflow management support for a wider range of work environments. It develops a sound theoretical foundation based on Activity Theory to deliver an implementation of an approach for dynamic and extensible flexibility, evolution and exception handling in workflows, based not on proprietary frameworks, but on accepted ideas of how people actually perform their work activities.
An implementation is produced called "worklets", which provides an extensible repertoire of self-contained selection and exception-handling processes, coupled with an extensible 'ripple-down" rule set. Using a Service-Oriented Architecture (SOA), a selection service provides workflow flexibility and adaptation by allowing the substitution of a task at runtime with a sub-process, dynamically selected from its repertoire depending on the context of the particular work instance. Additionally, an exception-handling service uses the same repertoire and rule set model to provide targeted and multi-functional exception-handling processes, which may be dynamically invoked at the task, case or specification level, depending on the context of the work instance and the type of exception that has occurred. Both expected and unexpected exceptions are catered for in real time.
The work is formalised through a series of Coloured Petri Nets and validated using two exemplary studies: one involving a structured business environment and the other a more creative setting. The service has been deployed for the well-known, open-source workflow environment YAWL, and is freely available for use and extension.
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