1 Ubiquitous Provision of Context-Aware Web Services

Context-aware Web services refers to an adaptive process of delivering contextually matched Web services to meet service requesters’needs at the moment. We define the term “context ” from two perspectives: one from service requesters, and the other from Web services. From the former perspective, context is defined as the surrounding environment affecting requesters ’ services discovery and access, such as requesters’ preferences, locations, activities, and accessible network and devices. From the latter perspective, context is defined as the surrounding environment affecting Web services delivery and execution, such as networks and protocols for service binding, devices and platforms required for service execution, and so on. This paper presents an ontology-based context model that enables formal description and acquisition of contextual information pertaining to service requesters and services. The context model is supported by context query and phrased acquisition techniques. We also report two context-aware Web services built on top of our context model to demonstrate how our context model can be used to facilitate Web services discovery and Web content adaptation. Implementation details of the context elicitation system and the evaluation results of context-aware services provision are also reported. KEY WORDS: Context-aware, handheld devices, OWL-S, service oriented architecture, ubiquitous, Web service