Enabling Context-Awareness by Predicate Detection in Asynchronous Environments

摘要

Pervasive applications are involving more and more autonomous computing and communicating devices, augmented with the abilities of sensing and controlling the logical/physical environment. To enable context-awareness for such applications, we are challenged by the intrinsic asynchrony of the computing environment. Predicate detection is a well studied technique dedicated to detecting global predicates over asynchronous computations and can be employed to achieve context-awareness of the asynchronous environment. However, there is no methodological framework which guides us to systematically apply the abstract predicate detection theory to the development of concrete context-aware applications. To this end, we present the Predicate Detection-based Context-Awareness (PD-CA) framework. PD-CA maps the concepts of context-awareness to concepts of predicate detection. PD-CA also presents a design process of providing middleware support for context-aware applications. Under the guidance of the PD-CA framework, we design and implement the Middleware Infrastructure for Predicate detection in Asynchronous environments (MIPA). We also propose the programming toolkit to facilitate the development of context-aware applications based on MIPA, and demonstrate the use of the toolkit by a case study of a chemical plant safety management application. Experimental evaluations show the performance of MIPA in enabling context-awareness despite of the asynchrony.