Multipath TCP(MPTCP)is the most significant extension of TCP that enables transmission via multiple paths concurrently to improve the resource usage and throughput of long flows.However,due to the concurrent multiple ...Multipath TCP(MPTCP)is the most significant extension of TCP that enables transmission via multiple paths concurrently to improve the resource usage and throughput of long flows.However,due to the concurrent multiple transfer(CMT)in short flow trans-mission,the congestion window(cwnd)of each MPTCP subflow is too small and it may lead to timeout when a single lost packet cannot be recovered through fast retransmission.As a result,MPTCP has even worse performance for short flows compared to regular TCP.In this paper,we take the first step to analyze the main reason why MPTCP has the diminished performance for short flows,and then we propose M PTCP-SF,which dynamically adjusts the number of subflows for each flow.In particular,MP TCP-SF firstly analyzes the distribution characteristics of the web objects to extract two thresholds to be used for classifying each flow.After eceiving each new ACK,M PTCP-SF periodically counts the data being sent based on per-flow and uses the threshold to classify the we blows.Finally,MPTCP-SF dynamically switches path scheduling model for different classification flows.We conduct extensive experiments in NS3 to evaluate its efficiency.Our evaluation proves that MPTCP-SF decreases the completion time of short flows by over 42.64% com-pared to MPTCP,and the throughput achieved by MPTCP-SF in transmitting long flows is about 11.11%higher than that of MPTCP in a WLAN/LTE wireless network.The results successfully validate the improved performance of MPTCP-SF.展开更多
针对传统的WebGIS系统研究开发中存在的人机交互性差、运行速度慢等缺陷,提出了基于Adobe Flex框架和表述性状态传递(Representational State Transfer,REST)的WebGIS系统的解决方案,并应用于防汛信息管理系统的开发中。系统采用Flex实...针对传统的WebGIS系统研究开发中存在的人机交互性差、运行速度慢等缺陷,提出了基于Adobe Flex框架和表述性状态传递(Representational State Transfer,REST)的WebGIS系统的解决方案,并应用于防汛信息管理系统的开发中。系统采用Flex实现表示层的呈现,降低了系统的开发难度,增强了系统的用户体验性;使用REST技术框架解决了矢量地图的发布繁琐、服务器端和浏览器端之间响应速度慢的问题,为WebGIS的应用开发提供了新的思路。展开更多
为解决基于表述性状态转移(Representational state transfer,REST)的Web服务安全,采用互联网上进行分布式计算的基本构造块,以基于REST的面向资源的架构来设计Web服务,并根据安全的需要设计整个安全模型。该模型响应性好,提高了扩展性...为解决基于表述性状态转移(Representational state transfer,REST)的Web服务安全,采用互联网上进行分布式计算的基本构造块,以基于REST的面向资源的架构来设计Web服务,并根据安全的需要设计整个安全模型。该模型响应性好,提高了扩展性,简化了软件需求,兼容性强。展开更多
基金This work is supported by the National Natural Science Foundation of China(No.61602171,61602172)Scientific Research Fund of Hunan Provincial Education Department(No.17C0960,16C0050)Hunan Provincial Natural Science Foundation of China(No.2017JJ2016).
文摘Multipath TCP(MPTCP)is the most significant extension of TCP that enables transmission via multiple paths concurrently to improve the resource usage and throughput of long flows.However,due to the concurrent multiple transfer(CMT)in short flow trans-mission,the congestion window(cwnd)of each MPTCP subflow is too small and it may lead to timeout when a single lost packet cannot be recovered through fast retransmission.As a result,MPTCP has even worse performance for short flows compared to regular TCP.In this paper,we take the first step to analyze the main reason why MPTCP has the diminished performance for short flows,and then we propose M PTCP-SF,which dynamically adjusts the number of subflows for each flow.In particular,MP TCP-SF firstly analyzes the distribution characteristics of the web objects to extract two thresholds to be used for classifying each flow.After eceiving each new ACK,M PTCP-SF periodically counts the data being sent based on per-flow and uses the threshold to classify the we blows.Finally,MPTCP-SF dynamically switches path scheduling model for different classification flows.We conduct extensive experiments in NS3 to evaluate its efficiency.Our evaluation proves that MPTCP-SF decreases the completion time of short flows by over 42.64% com-pared to MPTCP,and the throughput achieved by MPTCP-SF in transmitting long flows is about 11.11%higher than that of MPTCP in a WLAN/LTE wireless network.The results successfully validate the improved performance of MPTCP-SF.
文摘针对传统的WebGIS系统研究开发中存在的人机交互性差、运行速度慢等缺陷,提出了基于Adobe Flex框架和表述性状态传递(Representational State Transfer,REST)的WebGIS系统的解决方案,并应用于防汛信息管理系统的开发中。系统采用Flex实现表示层的呈现,降低了系统的开发难度,增强了系统的用户体验性;使用REST技术框架解决了矢量地图的发布繁琐、服务器端和浏览器端之间响应速度慢的问题,为WebGIS的应用开发提供了新的思路。
