A Context-AwareWorkflow System Supporting a User´s Dynamic Service Demands in Ubiquitous Environments

A context-aware service in ubiquitous computing environments aims to supply services according to a user´s situation information that is dynamically occurring. The existing context-aware workflow systems provide a context-aware service based on a workflow that uses a user´s situation information as services´s transition condition. But they can´t apply user´s new service demands, which may be dynamically occurring even when a workflow is on going, to the workflow scenario. In this paper we propose a context-aware workflow system that can reconstruct autonomously and efficiently an initial workflow scenario according to user´s dynamic service demands, and can adopt the new service demands into the initial workflow scenario without interrupting or deleting the on-going workflow services. The proposed system uses an incremental parsing method to provide context-aware services without interrupting of service through recognizing exactly the place holder that has to be changed in a workflow scenario and reconstructing only the part under the influence of the changes. Therefore, a user can apply his new service demands to a scenario document regardless of the time and the space, and he can be guaranteed to support the continuous execution of a context-aware service without the discontinuance of services according to the workflow scenario, which describes the new service demands.