Technical Report Number
Traditionally, a distributed system has been viewed as a collection of fixed computational elements connected by a static network. Prompted by recent advances in wireless communications rechnology, the emerging field of mobile computing is challenging these assumptions by providing mobile hosts with connectivity that may change over time, raising the possibility that hosts may be called upon to operate while only weakly connected to or while completely disconnected from other hosts. We define a concurrent mobile system as one where independently executing coponents may migrate through some space during the course of the computation, and where the pattern of connectivity among the components changes as they move in and out of proximity. Note that this definition is general enough to encompass a system of mobile hosts moving in physical space as well as a system of migrating software agents implemented on a set of possibly non-mobile hosts. In this paper, we present Mobile UNITY, which is a notation for expressing such systems and a logic for reasoning about their temporal properties. Based on the UNITY language of Chandy and Misra, our goal is to find a minimalist model of mobile computation that will allow us to express mobile components in a modular fashion and to reason formally about the possible behaviors of a system composed from mobile components. A simplified serial communication protocol among components which can move in space serves as an illustration for the notation.
Roman, Gruia-Catalin and McCann, Peter J., "An Introduction to Mobile UNITY" Report Number: WUCS-97-44 (1997). All Computer Science and Engineering Research.