Ontology-based service layering for facilitating alternative service discovery

To provide dynamic services for users in a ubiquitous environment, an efficient context-aware service discovery mechanism is essential. Most of current researches are focused on composing services which satisfy pre-defined service specifications, by checking the availability of the devices and finding services that satisfy the user's preference. In this paper, we introduce a process for building a ubiquitous service ontology, and propose the specification to describe each service. With the service ontology, using the concept of service availability, not device availability, our method could discover the most appropriate service, and replace of it if the service requested is unavailable. The experimental result shows that our service ontology for home domain could reduce, on the average, more than 36% of the time required to discover alternative services compare to using just a flat list of services.