The Research And Design Of Closed-Loop Lifecycle Management System Middleware In The Context Of IoT

With the development of Internet of things and information communication technology, how to use existing technology and protocols to eliminate the information barriers in different stages of product lifecycle, so as to close the product lifecycle information and knowledge flow, enhance the level of tracking and tracing products, improve the capacity of product design and manufacturing and provide innovative products and services, become problems urgently to be solved. In order to solve these problems, closed-loop lifecycle management provides new ideas and methods. However, it remains unperfected, such as lacking generic standard for CL2M (CL2M is short for closed-loop lifecycle management) system middleware and also having no independent and generic CL2M system middleware, which are key problems to cope with basic data service on product during lifecycle.Based on the analysis of characteristics regarding CL2M system middleware, MQTT (MQTT is short for Message Queue Telemetry Transportation) is introduced and chose as the standard for CL2M system middleware. The key problems of CL2M system middleware are then studied. After that, the scheme of CL2M system middleware is provided and design and implementation are also completed. The main work of this thesis are as follows:1. The PMI (PMI is short for PROMISE Message Interface) and QLM(QLM is short for Quantum Lifecycle Management) standard, which proposed for CL2M system middleware, are introduced in detail. The existing problems of them, such as lacking of error handling mechanism, security and privacy, and being not suitable for resource constrained devices and etc, are also pointed out. The MQTT and PMI, QLM are then compared and analyzed. After that, MQTT is expanded on the client ID and message content format, meanwhile the function which used for specifying emergency factor of message is also provided. At last, MQTT is adopted as the standard for CL2M system middleware.2. The key problems of CL2M system middleware are analyzed and the methods are provided. The model of CL2M system middleware, which based on MQTT, is defined. Netty, which based on NIO design pattern, is adopted to meet the requirements of concurrency of middleware. In order to realize priority routing strategy, the emergency factor is defined to differentiate message. The filtering algorithm of invalid message based on multi-dimension counting bloom filter is then designed. Finally, in order to realize the decoupling of the CL2M agent function from the CL2M system middleware, the CL2M agent is designed and integrated with the capacity of product data collection.3. Based on the analysis of key problems, objective and requirements of CL2M system middleware, the system architecture, function modules and driving mechanism are designed. The main work include the design and implementation of processing procedures of all modules, the implementation of message filter algorithm based on multi-dimension counting bloom filter, the design of priority routing strategy based on multi-priority queue, the use of XML file to check format of message content and etc.4. In order to test the effectiveness of message filtering, concurrency, message processing time, system throughput and availability of CL2M system middleware, the test system is designed and then tests are carried out in detail. The experimental results finally show that the middleware meets the objective and requirements.