Modeling Context and Services for a Context Aware System(CREDO).

CREDO is a context aware architecture which is built on a subscription based paradigm. Credo supports both SIP (session initiation protocol) as well as HTTP. This system compromises of Context providers and Context Consumers, the consumers need to discover these services and subscribe to them giving restriction on when they should be notified.We modeled these services using OWL-S and extended OWL-S to allow subscription with restriction specified in SWRL or Joshua Rules. We also added a SIP grounding to OWL-S.