A Framework for Building Customized Adaptation Proxies

Abstract

This article presents a framework for the development of adaptive proxies for context-aware mobile applications. The framework is in charge of collecting clients' current context (device and network), and trigger the appropriate adaptations. MoCA's Proxy Framework offers mechanisms for cache management, as well as for adaptation management. Developers need only create their application-specific adaptations (developing adapters modules) and define trigger conditions, priorities and selectors. This is done by specifying rules in XML format, which define the actions to be applied at the moment of a context change. The other extension point of the Proxy Framework is the caching policy to be used. Keywords:Mobile Computing, Context-awareness, Proxy, Framework IntroductionA common element in the architecture of distributed applications for mobile networks is a proxy [3,4], which intercepts the messages exchanged between the mobile clients and servers, and which is in charge of executing a number of transformations, adaptations or management functions on behalf of one or several clients, such as content adaptation, protocol translation, caching, personalization, user authentication, handover management, etc. The main advantage of using such an intermediary is to bridge the wired-wireless gap, and make all mobility, connectivity and context-dependent issues transparent to the application developer.Although each distributed application for such networks has specific adaptation and transformation requirements, there are a number of common and recurrent components and interaction patterns used for implementing usual *This project is partially funded by CNPq, Grants 55.2068/02-2 and 47.9824/04-5.