The Research Of Control Mechanisms And Its Implication Of Context-aware Application In Distributed Environment

Context-aware computing is a cross research field including pervasive computing, distributed computing, mobile computing and wearable computing. Its great advantage is the uniform context-aware environment based on all kinds of context-aware information featuring the entity status (physical status, social status). It's based on the uniform context-aware environment and the context inference that context-aware computing can construct a entity-centered intelligent application autonomously reacting to the context varying.At present,many developers or researchers use object-oriented pattern to analyse the processing of context information.But context-aware application is a kind of classic knowledge application. The knowledge include not only surrounding's changing context information, but also all kinds of growing objective knowledge used to improve the system's intelligence. In object-oriented pattern, the system's structure and knowledge that can be processed is fixed after the design, which can't change with environment's evolving. So the object-oriented pattern can't cope with the growing knowledge of context-aware system. But the growing knowledge is key to improve the intelligence of system.To solve the problem, we use ECA(Event-Control-Action) rule pattern to analyse the behavior of context-aware system. We construct rule base base on ECA rule. The rule base is just like expert system's rule base. By that way, we master the context-aware system's essence that it's a kind of knowledge system. So we can set up the control mechanism of context-aware system based on its essence of knowledge. And we can improve the intelligence through the growing knowledge.We use Reaction RuleML based on standard as our context rule description language to construct context-aware rule system. Rule engine is the core of knowledge system, which support the executing of rules. There are several rule engines with the expert system's rapid developing .Through comparing of the features of the rule engines, we select jDrew as our ECA rule engine.In practice, context-aware system is a kind of distributed network system. We propose an architecture based on web services, which can be used to construct distributed context-aware application. We solve two problems in the architecture's implemention: the encapsulating jDrew to Web services and using WS-Eventing to transfer context event.Finally, analysis how to trigger jDrew reasoning the rules through the context of events conveied by WS-Eventing, and test the jDrew's efficiency in Web services environment through experimental.The research has great perspective in context-aware application field such as mobile context-aware applications, intelligent space etc.