A QoS Communication Solution In Railway Control And Management System

China railway control and management system (CRCM) is a huge distributed system that constituted by serious subsystems. It depends on cooperation of subsystems that the whole CRCM system functions normally. The degree of cooperation of these subsystems determines efficiency of the whole system's function to a certain degree. At present, these subsystems are independent each other and can not share information with each other efficiently, which lower CRCM system's efficiency, so it becomes very important to integrate these subsystems so as to improve railway's level of management and quality of service.Integrate the CRCM system should meet the following requirement: autonomous controllability and autonomous coordinability, online fault tolerant online maintenance and online expansion. Ah the same time, there are various types of data flows in CRCM system. Different types of data flows have different communication demand, integrate system need to provide the QoS communication service in WAN.Traditional Client/Server(C/S) architectures route all communications through a centra! server. This makes them ill-suited to handle autonomous coordinability, online fault tolerant, online maintenance and online expansion. When it comes to Publish/Subscribe (P/S) architectures, it can meet the integrate demand of the CRCM well.This essay analysis the data flows semantics in CRCM system, compartmentalize them into 3 types: common data flow, operation data flow and control data flow. Then the essay proposes a P/S based 2-level architecture QoS communication solution in CRCM, gives the critical technologies of this solution include the establish of the multicast group dynamic reliable mechanism and the node's join and leave. At last, the essay simulates and compares the C/S integrate scheme and P/S scheme, analysis the main parameter of the model.