Research On Performance Optimization Of Vehicle Monitoring System Based On WebGIS

In recent years, the rapid growth of the number of vehicles causes a serious problem to transport, intelligent transportation has become the key to solve these problems. The vehicle monitoring system based on WebGIS modified the traditional transport system by integrating the advanced communications technology with electronics technology and geographic information technology, so that the acquisition and transmission of traffic information is more intelligent, fast and accurate. However, in practical applications, massive track data and multiple clients’high concurrent access raise many problems of systems performance.To solve these problems, two strategies of performance optimization is proposed in this thesis, First of all, due to the problems of low query efficiency, insufficient storage space and low user response time which are caused by the huge amount of data of trajectory, a hybrid trajectory compression algorithm based on the multiple spatio-temporal characteristics is proposed to do the compression of the trajectory. On the one hand, in the algorithm, a new online trajectory compression strategy based on the multiple spatio-temporal characteristics is adopted in order to choose the characteristic points more accurately by using the position, direction and speed information of GPS point. On the other hand, the hybrid trajectory compression strategy which combined online compression with batched compression is used, and the Douglas batched compression algorithm is adopted to do the second compression process of the hybrid trajectory compression. The experiment results show that strategy based on multiple spatio-temporal characteristics reduces significantly, although the compression ratio fells slightly compared with the existing spatio-temporal compression algorithm. By choosing appropriate cycle time of batching, the compression ratio and compression error of this algorithm are improved compared with the existing spatio-temporal compression algorithm.Furthermore, in order to solve the problem of load imbalance when many terminals access communication platform concurrently in cluster, a dynamic feedback-based load performance ratio scheduling algorithm is proposed. On the base of weighted least connection scheduling algorithm and load feedback scheduling algorithm the concepts of load performance ratio and load remaining capacity are proposed, which are used to determine load distribution. The experiment results show that the average response latency and throughput of this algorithm are improved compared with weighted least connections scheduling algorithm and dynamic feedback scheduling algorithm.Finally, we have developed a prototype of vehicle monitoring system based on WebGIS. The system is consisted with vehicle terminals, communications platform, application platform, and is composed of GPS, WEB and GIS technology, and the proposed trajectory compression and load balancing algorithm are implemented in the system. Experiment results show that not only the user request response time is reduced, but also the stability of the whole system is improved by performance optimizing, and the system performance problem is solved effectively.