  In pervasive computing environments, various entities often have to cooperate
and integrate seamlessly in a \emph{situation} which can, thus, be considered
as an amalgamation of the context of several entities interacting and
coordinating with each other, and often performing one or more activities.
However, none of the existing context models and ontologies address situation
modeling. In this paper, we describe the design, structure and implementation
of a generic, flexible and extensible context ontology called Rover Context
Model Ontology (RoCoMO) for context and situation modeling in pervasive
computing systems and environments. We highlight several limitations of the
existing context models and ontologies, such as lack of provision for
provenance, traceability, quality of context, multiple representation of
contextual information, as well as support for security, privacy and
interoperability, and explain how we are addressing these limitations in our
approach. We also illustrate the applicability and utility of RoCoMO using a
practical and extensive case study.
