A DMVOCC-MVDA(distributed multiversion optimistic concurrency control with multiversion dynamic adjustment)protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments.At...A DMVOCC-MVDA(distributed multiversion optimistic concurrency control with multiversion dynamic adjustment)protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments.At the mobile hosts,all transactions perform local pre-validation.The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle.Transactions that survive in local pre-validation must be submitted to the server for local final validation.The new protocol eliminates conflicts between mobile read-only and mobile update transactions,and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions.Mobile read-only transactions can be committed with no-blocking,and respond time of mobile read-only transactions is greatly shortened.The tolerance of mobile transactions of disconnections from the broadcast channel is increased.In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants.The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate,restart rate,commit rate.Under high work load(think time is 1s)the miss rate of DMVOCC-MVDA is only 14.6%,is significantly lower than that of other protocols.The restart rate of DMVOCC-MVDA is only 32.3%,showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions.And the commit rate of DMVOCC-MVDA is up to 61.2%,which is obviously higher than that of other protocols.展开更多
提出一种基于国际交通行业EN50128标准的地铁屏蔽门PSC(platform screen door central controlpanel)综合自动化系统的设计方案,通过引入组态技术、实时数据库技术和仿真技术来解决目前监控系统无法自适应地铁行业的定制化需求的问题....提出一种基于国际交通行业EN50128标准的地铁屏蔽门PSC(platform screen door central controlpanel)综合自动化系统的设计方案,通过引入组态技术、实时数据库技术和仿真技术来解决目前监控系统无法自适应地铁行业的定制化需求的问题.针对地铁屏蔽门监控系统希望根据站点的改变灵活地对参数进行配置以及满足状态信息采集实时性的需求,提出了基于分布式、模块化设计的软件系统实施方案和详细设计以及硬件系统网络架构的改进方案.实际应用结果说明该系统的设计方案能够满足地铁行业的应用需求.展开更多
基金Project(20030533011)supported by the National Research Foundation for the Doctoral Program of Higher Education of China
文摘A DMVOCC-MVDA(distributed multiversion optimistic concurrency control with multiversion dynamic adjustment)protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments.At the mobile hosts,all transactions perform local pre-validation.The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle.Transactions that survive in local pre-validation must be submitted to the server for local final validation.The new protocol eliminates conflicts between mobile read-only and mobile update transactions,and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions.Mobile read-only transactions can be committed with no-blocking,and respond time of mobile read-only transactions is greatly shortened.The tolerance of mobile transactions of disconnections from the broadcast channel is increased.In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants.The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate,restart rate,commit rate.Under high work load(think time is 1s)the miss rate of DMVOCC-MVDA is only 14.6%,is significantly lower than that of other protocols.The restart rate of DMVOCC-MVDA is only 32.3%,showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions.And the commit rate of DMVOCC-MVDA is up to 61.2%,which is obviously higher than that of other protocols.
文摘提出一种基于国际交通行业EN50128标准的地铁屏蔽门PSC(platform screen door central controlpanel)综合自动化系统的设计方案,通过引入组态技术、实时数据库技术和仿真技术来解决目前监控系统无法自适应地铁行业的定制化需求的问题.针对地铁屏蔽门监控系统希望根据站点的改变灵活地对参数进行配置以及满足状态信息采集实时性的需求,提出了基于分布式、模块化设计的软件系统实施方案和详细设计以及硬件系统网络架构的改进方案.实际应用结果说明该系统的设计方案能够满足地铁行业的应用需求.
