A Design And Implementation Of Context Server In Context-aware Computing

As the popularization of mobile devices grows, the demands for mobile services increase. The major characteristic of the mobile services, compared with traditional web services, is the differences of the devices, the limited transmission abilities, and the increasing demands for customized services. Therefore, services provided to mobile users need more service preferences, such as device capabilities, device location, available local web transmission resources and interests of the users. Those service preferences are named "context". This kind of "services according to demands" computing environment is called "context-aware computing". The context-aware computing technique is an important issue to assure the device independence in current mobile services, which is theoretical significant and practical worthy.A context server provides context services for the context-aware computing. The issue discussed in this paper, is the design and implementation of the context server, aiming at the context-aware application.This paper discusses and establishes a context server prototype model, CSWMS (Context Server for Web-based Mobile Service). The model takes CC/PP standard to be the model of context. According to the requirement of the context server, it realizes the completed processes of context collection, explanation, disposal to model encapsulation, and the functions such as establishing the context repository and managing the history records.CSWMS supports the cooperation of different sensors, and two different service modes as "require-response" and "customization", which are able to suit for different use cases.Using the rule engine technique, we realize the explanation process from the physical context to the logical context in CSWMS, so that the user may customize the context services by defining rule documents and rule configuration documents. The use of the rule engine advances the flexibility of the context explanation. Based on those design thoughts and methods mentioned above, CSWMS realizes the processes of context collection, management and explanation. It can provide context services for adaptive mobile application based on web.