An Adaptive Context-Aware Publish–Subscribe Component Metamodel

Abstract

There are plenty of solutions in which the functionality for context awareness is separated from the domain-specific functionality. Also, there are multiple ways of modeling, gathering, and processing context-related information; however there are only two main types of context dissemination, also known as context propagation: event based, or query based. This means that most context-aware systems use events and require publish–subscribe mechanisms. However, a few include context as part of the event-propagation process; also, a few context models and metamodels consider events when modeling context-related data, even though such data are propagated though events. This document proposes a metamodel that introduces the publish–subscribe logic of distributed event-based systems (DEBSs) to the modeling of context-related information and to the modeling of context-dependent interactions and adaptations. This approach has two main advantages: on one hand, no assumptions need to be made regarding the type of context or the domain of the application when considering interactions and adaptations that depend on context. On the other hand, by introducing context-related elements when considering event propagation, the DEBS middleware can filter events based on context and stop their propagation. Also, including other features of DEBSs such as event enrichment and transformations, will make for a more efficient dissemination mechanism. The metamodel suggested here could be used to model context, and context interaction between components. It can also be used when designing DEBS middleware that would take into account context when propagating events.