A Calculus of Mobility and Communication for Ubiquitous Computing

Ubiquitous computing makes various computing devices available throughout the physical setting. Ubiquitous computing devices are distributed and could be mobile, and interactions among them are concurrent and often depend on the location of the devices. Process calculi are formal models of concurrent and mobile systems. The work in this thesis is inspired by the calculus of Mobile Ambients and other process calculi such as Calculus of Communicating Systems which have proved to be successful in the modelling of mobility, communication and structure of systems. We start by developing operational semantics for the calculus of Mobile Ambients and Push and Pull Ambient Calculus, and prove that the semantics are sound and complete with respect to the corresponding underlying reduction semantics. This thesis proposes a Calculus of Communication and Mobility, denoted by CMCPCA, for the modelling of mobility, communication and context awareness in the setting of ubiquitous computing. CMCPCA is an ambient calculus with the in and out capabilities of Cardelli and Gordon as well the push and pull capabilities of Phillips and Vigliotti. CMCPCA has a new form of global communication similar to that in Milner’s CCS. We define a new notion of behavioural equivalence for our calculus in terms of an observation predicate and action transitions. Thus, we define barbed bisimulation and congruence, and capability barbed bisimulation and congruence. We then prove that capability barbed congruence coincides with barbed congruence. We also include in the calculus a new form of context awareness mechanism that allows ambients to query their current location and surrounding. We then propose reduction semantics and operational semantics for the context awareness primitives, and show that the semantics coincide. Several case studies and a variety of small examples show the expressiveness and usefulness of our calculus.