Research On Mobile Middleware In Wireless Environment

Recent years, mobile computing devices, laptop computers, smart phones, personal digital assistants and the like are gaining wide popularity. They bring much convenience to our everyday life. But mobile computing has its own characters. Developing mobile applications will meet great challenges. Mobile devices face temporary loss network connectivity when move; they are likely to have scarce resources, such as low battery power, slow CPU speed and little memory; they are required to react to frequent and unannounced changes in the environment, such as variability of network bandwidth, and in the resources availability.Middleware can shield heterogeneous platforms, support interoperation on distributed systems. Traditional middleware depends on the principle of"black box". It is short of essential flexibility and adaptability, and can not satisfy the need of mobile computing. With the conception of open implementation, reflective middleware opens itself to users effectively and restrictively. Applying reflection mechanism to middleware design and implementation phases, supplies the powerful technical support for aiming at adaptable and configurable. Meanwhile, mobile applications can check the types of service that middleware provide at run time, and build request-transfer dynamically.In this paper, firstly, a comparison between mobile distributed system and fixed system is given. From that, the paper describes the special requirement of mobile computing. Also the paper studies the concept of reflection related, middleware techniques, and introduces main reflective middleware. To support adaptation and dynamic reconfiguration, the middleware should have the ability of context aware. Then, the paper discusses context aware techniques, puts forward a model of context-aware system. It is contained in the CARM architecture below. Finally, based on the advantage of successful reflective middleware such as dynamicTAO,CARISMA, ReMMoC, a architecture named CARM which supports context-aware, asynchronous communication and dynamic reconfiguration is proposed. In the key module of adaptation engines, an algorithm is designed to solve policy collision. Besides, proper interception points are set to intercept user's requests. In this way, CARM can support QoS management without affecting the normal functions of middleware. To prove the efficiency of the CARM architecture, it is applied in the project of"Farm product Detection System". From the result, it can provide an instance of a concrete application development on top of it to show its support for context-aware application development.