【作者】 何浩源；

【导师】 刘晓强；

【作者基本信息】 东华大学 ， 计算机软件与理论， 2009， 硕士

【摘要】 我国正处于城市轨道交通建设和应用的繁荣时期,传统的轨道交通乘客信息系统(PIS)在控制中心将多媒体信息和运营信息合成并发送给车站、车载终端设备本地播放,这给信息更新维护和紧急事故处理带来了很多不便,同时,乘客对轨道交通的信息服务能力也不断提出更高要求。因此如何实时地、快捷地将信息发布出去成为轨道交通领域急需解决的课题之一。本文提出了一种基于流媒体技术的乘客信息系统的实现方案,重点研究了PIS中流媒体服务、流媒体服务负载均衡和乘客信息播放控制子系统。通过研究与完善开源流媒体服务器VLC,给出了创建PIS流媒体服务的方法;在流媒体集群系统中,设计了一种能支持多种负载均衡算法框架的负载均衡器;对于乘客信息的控制与播放,设计了一种包含若干业务逻辑处理能力的浏览器的客户端播放器,解决了乘客信息的交互、信息控制调度和信息播放等问题。其主要研究内容包括:1.PIS流媒体服务。由于典型的商用流媒体服务器存在成本、可移植性、可定制性等方面不足,本文采用了完全开源的VLC流媒体服务器。通过分析其源码及相关资料,总结VLC体系结构和创建流媒体服务的方式,完善VLC流媒体服器的功能,提出了创建PIS流媒体服务的机制。采用哈希函数、XML文件和TCP/IP网络传输,分别解决了流媒体服务中流媒体节目的命令数据、命令管理和命令交互等问题。2.流媒体服务负载均衡。在PIS流媒体服务中,采用多台普通流媒体服务器构成集群系统能保证可靠,优质的流媒体服务。本文提出了一种构建流媒体集群系统的体系结构,并研究了其负载均衡器。采用面向对象设计方法,设计了一种能支持多种负载均衡算法框架的负载均衡器,其负载均衡算法和流媒体服务器信息均记录在XML文件中,且信息可配置。3.PIS信息播放控制。通过比较C/S和B/S模式下MIS系统特点,结合轨道交通的应用,设计了一种基于浏览器且包含实时调度算法和运营信息更新等业务逻辑处理能力的客户端播放器。对于客户端播放器和Web服务器间信息交互采用XML文件为载体,通过TCP/IP协议传输;对于PIS中信息的控制采用经典的静态实时调度算法RMS;流媒体的播放通过VLC网页插件,轨道交通运营等交互信息,通过COM技术执行网页脚本实现。4.系统实现。论文最后设计并实现了PIS中流媒体服务、流媒体服务负载均衡和乘客信息播放控制子系统。本文的研究成果已经在上海地铁示范应用,该研究方案不仅适用于轨道交通PIS系统,还可应用到大型超市、商场、医院、学校等信息发布场所。更多还原

【Abstract】 The construction of urban railway is booming in China.Traditionally, in the Passenger Information System(PIS),the multimedia and operation information are composed at control center,and then sent to platform device where the information is played.It is difficult for traditional urban railway system to update information and deal with emergency.At the same time,passengers put forward high demands for PIS services, therefore how to publicize information rapidly becomes one of the urgent problems for PIS.This paper presents an implemental approach of PIS based on the streaming media technology,concerning subsystems of streaming media service,load balancing of streaming media services,and controlling & playing passenger information.By researching the architecture of VLC, we addless a method to offer streaming media service in PIS.A novel load balancer supporting a lot of load balancing algorithms.is proposed in streaming media clustered system.A browser-based player,which could process service logically,is designed to control and play passenger information.Also the interaction,scheduling and playing of passenger information and other problems have been solved in this paper.The major researches are as following:1.Streaming media service.The commercial streaming media servers are lacking in cost,portability and customizability,so VLC which is an open source streaming media server & player is used to offer streaming media service in PIS.We propose the mechanisms of creating streaming media service in PIS by analysing the source code of VLC,summarizing the architecture of VLC,comparing the patterns of creating streaming media service and consummating the functions of VLC.Through hash functions,XML files and network transmissions,the VLC command data, management of command,interaction of command and other problems in streaming media service are also solved respectively.2.Load balancing of streaming media service.In order to gain high quality of streaming media service,streaming media clustered system is adopted.This paper brings forward a method to design the architecture of streaming media clustered system and studies the load balancer. Object-oriented method is used to design the load balancer which supports the framework of several kinds of load balancing algorithms, and its load balancing algorithms and streaming media servers are configured in XML files.3.Controlling & playing passenger information of PIS.By comparing the features between C/S and B/S and analysing the demands of urban railway,we design a browser-based player which holds the capability of processing service logically,including real-time scheduling algorithm and operation information updation.The information interacting between client player and Web server is transmitted through TCP/IP with XML files.The information of PIS is controlled by RMS which is a classic real-time scheduling algorithm.Streaming media is played in VLC plug-in.Urban railway passenger information is updated by executing javascript functions through COM.4.System implementation.In the end,several subsystems including streaming media service of PIS,load balancing of streaming media service,and controlling & playing passenger information are designed and realized.The project has gone into operation in Shanghai metro.The research approach is can be used not only in passenger information system of urban railway but also in other information diffusion fields such as hypermarket,hospital,university and so on.更多还原