Researches On Reflective Mobile Application Middleware

The rapid growths of wireless technology, coupled with advances in mobile computing devices, have fundamentally changed the landscape of traditional distributed computing. Unlike fixed network computing, mobile computing running in a wireless environment suffers from limited resources and often experiences constant changes in the availability of resources, therefore, applications have to be aware of, and adapt to, variations in the execution context, in order to deliver a good quality of service to their users. It can simplify and facilitate the development of mobile application that using middleware to deal with the awareness of context and adaptation to it.Reflective principle, used to reconfigure middleware dynamically, is effective to achieve context-awareness, as a reflective system can modify itself through introspection and intercession. The CARISMA platform of London University is a mobile computing middleware, which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. As different users may have different quality-of-service needs, and applications, in an attempt to fulfill these needs, may customize middleware behavior in conflicting ways. The CARISMA platform uses a microeconomic approach that relies on a particular type of sealed-bid auction to solve the problem of policy redundancy, while helpless to policy short.Based on CARISMA, this paper improves the metadata, application profile, to describe the baselevel more appropriately and refines the policy conflicts and the cause of them. To fulfill most satisfaction of every application involved, this paper proposes a concession mechanism to solve the problem of policy short. In addition, this paper modifies the algorithms of bid computing in CARISMA, compares QoS afforded by policy with the required QoS of user to make the elected policy satisfy the quality of service of different users, and imports minus bid to express running cost in order to simplify bid computing.According to the policy choice mechanism proposed above, this paper provide two different distributed algorithms to implement it, the first one that attempts to minimize communication costs, and the second one that aims to minimize computation costs. Then, this paper discusses their similarities and, mainly, their differences. More over, this paper implement the algorithms to argue the feasibility and validity of our concession mechanism. Finally, this paper describes the architecture of a Context-Aware Reflective Mobile Application Middleware, and provides an instance of a concrete application development on top of it to show its support for context-aware application development.