A context-aware workflow system for dynamic service adaptation

Abstract

The workflow model has been successively applied to traditional computing environments such as business processes and distributed computing in order to perform service composition, flow management, parallel execution, and time-driven services. Recently, there have been many studies to adopt the workflow model into ubiquitous computing environments for context-aware and autonomous services. A service in ubiquitous computing environments must be executed according to a user's situation information, which is generated dynamically from sensors. Such existing workflow systems as FollowMe and uFlow support context-aware services through workflow models. However, when a user's situation is dynamically changed, the systems don't have a method to immediately adopt the change into an already on-going service workflow. In this paper, we propose a context-aware workflow system, which can apply changes of user's service demand or situation information into an on-going workflow without breaking its operation. The suggested workflow system can re-apply the new services into an initial workflow scenario without interrupting or deleting workflow service. To do this, the proposed system represents contexts described in a workflow as an RDF-based DItree (Document Instance tree). The system uses the tree information to recognize an exact position to be changed in the on-going workflow for the user's situation changes, and to reconstruct only the position under the influence of the changes in the DItree. Therefore, the suggested system can quickly and efficiently apply a change of the user's new situation into an on-going workflow without much loss of time and space, and can offer a context-aware service continuously according to a new workflow. © Springer-Verlag Berlin Heidelberg 2007.