Context-aware workflow management in eHealth applications
PhD Thesis, Department of Mathematics and Computer Science
University of Basel, Switzerland
Workflows are a technology to structure work in functional non overlapping steps. They define not only the order of execution of these steps, and describe whether steps are executed in parallel, they also specify who or what tool has to fulfill which step. Workflows offer the possibility to automate work, to increase the understandability of processes, and they ease the controlling of process execution. The tools to manage workflows, so called workflow management systems (WfMSs), are traditionally rigid as they separate workflow definition done at build time from workflow execution done at run time. This makes them ill-suited for managing flexible, unstructured and rarely executed workflows. In this thesis we focus on the support of flexible processes in eHealth, which are affected by more foreseen than unforeseen events. To bridge the gap between rigid WfMSs and flexible workflows, we developed a concept for dynamic and context-aware workflow management called Flexwoman. Although our focus lies on flexible eHealth processes, Flexwoman is a generic approach that can be applied to several different application domains. Flexwoman supports the usage of context information to adapt processes automatically at run time to foreseen events. Additionally, processes can be manually adapted to handle unforeseen events. To achieve such a flexibility, context information from different sensors is unified to have internally the same representation and thus can be analyzed in the same way. The analysis and adaptation of workflows is executed with a rule engine. A rule engine can store, reason about and apply knowledge automatically and efficiently. Rules and application logic are separated, thus, rules can be changed during run time without affecting application logic or process description. Workflows are internally described by Hierarchical Colored Petri nets (HCPNs) and executed by a HCPN execution engine. HCPNs allow for a deterministic execution of workflows and can represent workflows on different levels of detail. In summary, in Flexwoman, significant context changes (events) trigger automated adaptations that replace parts of the workflow by sub workflows, which can in turn be adapted. Furthermore, sub workflows are saved in the organizational memory and can be reused in different parts of the workflow. Flexwoman’s event based behavior facilitates proactive adaptations instead of only allowing for adaptations while e.g. entering or leaving a task. Replacements are not bound to special places defined at build time but each part of the workflow, which has not been executed yet, can be replaced at run time. We implemented and evaluated the concept and showed that all required functionality is available and that the system scales.