Software Architecture Patterns for a Context-Processing Middleware Framework

Abstract

Ubiquitous applications are characterised by variations of their execution context. Their correct operation requires some continual adaptations based on the observation of their execution context. The design and the implementation of these observation policies is then the cornerstone of any ubiquitous applications. In this article, we propose COSMOS which is a framework for the principled specification and composition of context observation policies. With COSMOS, these policies are decomposed into fine-grained units called context nodes implemented as software components. These units perform basic context-related operations (e.g., gathering data from a system or network probe, computing threshold or average values) and are assembled with a set of well-identified architectural design patterns. In this article, COSMOS is motivated and illustrated with an example from the domain of mobile e-commerce applications.

A flexible context stabilization approach for self-adaptive application

“…Our simulations are based on COSMOS [12](Context Entities Composition and Sharing), which is a framework for context management that uses the FRACTAL [13] component model. We also use the simulation engine SIAFU [14] to generate contextual informations.…”

A Framework for Quality of Context Management

“…Pattern-oriented architecture of COSMOS For mapping context policies to context node hierarchies, COSMOS follows well-known design patterns [8], Factory method, Composite, Flyweight, and Singleton, enabling a scalable, extensible and efficient architecture [13]. …”

“…So we have defined a first version of a domain specific language (DSL) for describing the composition of context nodes and context processors [13] that we will extend with QoC declarations.…”

“…This paper proposes to integrate Quality of Context in COSMOS 1 (COntext entitieS coMpositiOn and Sharing), which is our framework for managing context data in ubiquitous environments [4,13]. The COSMOS framework relies on the Fractal 2 component-based middleware [2].…”

“…Information on the quality of context helps taking appropriate decisions and allows to identify uncertain context information saving processing time for deriving a pertinent description of the observed phenomenon. This paper presents a work in progress for integrating Quality of Context in COSMOS (COntext entitieS coMpositiOn and Sharing) [4,13], a component-based framework for managing context data in ubiquitous environments, and illustrates it throughout the example of the composition of context information to implement a network connectivity vs energy adaptation situation. …”