The Design And Implementation Of Heterogeneous Sensors Access Middleware Platform

With the flourishing development of computer science,Internet of Things(IoT)is becoming much more popular than ever.There are growing numbers of heterogeneous sensors gathering data in the network.Because the sensors accessed to IoT are produced by different manufacturers,various analyzing protocols and transmission modes are proposed to accommodate the communication between devices and appliances.It is necessary to implement a middleware platform to deal with the tremendous growth in the number of sensors.In this thesis,we proposed a heterogeneous sensors access middleware platform based on OSGi.The advantages of this platform can be divided into three areas:modularity,dynamic and scalability.The platform is responsible for accessing and analyzing the data from the heterogeneous sensor network and provides uniform interface to upper layer.Besides,under the normal operation of the whole system,new sensor module could be accessed and activated.First,the platform can be devided into three part:The protocol system is the most important subsystem which responsible for accessing and controlling the bundle.The publish/subscribe system is a middleware system which can make distributed systems involved in the message exchange into publisher and subscriber.The database system contains real-time database and historical database.The real-time database is used to record the reaction of real time sensors' data and the historical database is used to back up the sensor data.Second,the system based on OSGi has two main characteristics:modularity and dynamic.The modification of one subsystem will only affect the specific internal data operation without disturbing others as long as the message interaction meets the original specification.Therefore,the whole system has strong portability and scalability.The system based on OSGi framework supports the dynamic insertion of new module.Under the normal operation of the whole system,new module could be accessed and activated.Third,the platform is optimized by queuing theory and dynamic priority policy.Through the queuing theory,the size of the thread pool in protocol access module is dynamic programming,which could avoid frequent creation and destruction of thread.Through the dynamic priority algorithm to optimize the distribution module,the high priority protocol data will be distributed in time.