Design And Impelmentation Of Multimedia Resource Cache Server

With the rapid growth of mobile communication network, new multimedia value-added services need a higher performance of NCSP (Next Generation Core Service Platform).So there has become an emerging problem of solving the paradox of limited storage space in media server and large amount of resource in multimedia resource library, which has a direct effect on service experience in NCSP.As a technical solution, this paper proposed adding a MRCS (Multimedia Resource Cache Server) as a caching node between media server and multimedia resource library. In order to meet the resource requirement of media server and release the load of multimedia resource library effectively, the MRCS always caches the hottest resource according to a caching replacement algorithm.And the design of this algorithm and implementation of MRCS are emphases of this paper.Firstly we discussed the feasibility of using NFS (Network File System) as our resource transmission protocol and made sure that NFS is able to reach our performance requirement via experiments.We also made some research about the popularity of multimedia resource. By analyzing the service data of china mobile multimedia ring back tone service, we got a conclusion that the popularity of multimedia resource obeys Zipf distribution, which had a great significance to the following design of cache replacement algorithm in MRCS.Secondly based on the analysis of the pros and cons of classical LRU and LFU algorithems and the context of MRCS,we proposed a new cache replacement algorithm SLRU-K-EA(Sized-LRU with K Exponential Average), which introduces the factor of resource size and the idea of exponential average into the algorithm designing, and it balances the frequency feature and time feature of the resource access pattern well.And as experiments statistic showed, the SLRU-K-EA is competent for the resource file cache, whose average caching hit ratio is four percent higher than classical LRU-K. So it is believed that SLRU-K-EA is more suitable for a cache server based on NFS.Thirdly we introduced the whole design, function module design and key implementation of MRCS in detail.There was no doubt that the definition of data structure and the method of algorithm implementation was our key point. Actually we manage to reduce the time complexity effectively during the implementation of SLRU-K-EA.Generally speaking, with the development of multimedia value-added services,MRCS will make more contribution to the NCSP in providing different kinds of services and improving the quality of services.It is also believed that the proposed SLRU-K-EA algorithm in the paper is a good reference to other disk file caching systems.