Distributed Denial of Service （DDoS） attack is a major threat to the availability of Web service. The inherent presence of self-similarity in Web traffic motivates the applicability of time series analysis in the st...Distributed Denial of Service （DDoS） attack is a major threat to the availability of Web service. The inherent presence of self-similarity in Web traffic motivates the applicability of time series analysis in the study of the burst feature of DDoS attack. This paper presents a method of detecting DDoS attacks against Web server by analyzing the abrupt change of time series data obtained from Web traffic. Time series data are specified in reference sliding window and test sliding window, and the abrupt change is modeled using Auto-Regressive （AR） process. By comparing two adjacent nonoverlapping windows of the time series, the attack traffic could be detected at a time point. Combined with alarm correlation and location correlation, not only the presence of DDoS attack, but also its occurring time and location can be deter mined. The experimental results in a test environment are illustrated to justify our method.展开更多
针对传统瓦斯多级监管系统存在的不足,研究了基于ArcGIS Server Java ADF和JSF框架下的网络地理信息关键技术,构建了ArcGIS server API和Java ADF两种技术集成的开发方案,设计了基于元数据的属性数据分布式存储和空间数据集中部署的数...针对传统瓦斯多级监管系统存在的不足,研究了基于ArcGIS Server Java ADF和JSF框架下的网络地理信息关键技术,构建了ArcGIS server API和Java ADF两种技术集成的开发方案,设计了基于元数据的属性数据分布式存储和空间数据集中部署的数据库存储方案,实现了B/S结构中的浏览器端与服务器端的瓦斯多级监管系统。展开更多
目的研究定时作业和多作业协调机制在SQL Server 2005数据库系统中的实现方法.方法采用定时作业和多作业协调机制来有效地优化系统资源,设计基于多定时作业协调方式的管理系统软件及硬件结构方案;使用了两种多作业协调的方法.结果以某...目的研究定时作业和多作业协调机制在SQL Server 2005数据库系统中的实现方法.方法采用定时作业和多作业协调机制来有效地优化系统资源,设计基于多定时作业协调方式的管理系统软件及硬件结构方案;使用了两种多作业协调的方法.结果以某大型矿山B/S企业综合系统为例,建立了以多作业协调机制为核心的后台数据库动态管理系统,通过在定时作业中调用存储过程对系统数据库中的数据进行整理、备份、更新和汇总运算,并运用多作业协调机制实现多个定时作业的高效执行.结论工程应用证明在大型数据库系统中,多作业协调机制可以有效地解决数据冗余问题,提高了系统响应速率.展开更多
Web service applications are increasing tremendously in support of high-level businesses.There must be a need of better server load balancing mechanism for improving the performance of web services in business.Though ...Web service applications are increasing tremendously in support of high-level businesses.There must be a need of better server load balancing mechanism for improving the performance of web services in business.Though many load balancing methods exist,there is still a need for sophisticated load bal-ancing mechanism for not letting the clients to get frustrated.In this work,the ser-ver with minimum response time and the server having less traffic volume were selected for the aimed server to process the forthcoming requests.The Servers are probed with adaptive control of time with two thresholds L and U to indicate the status of server load in terms of response time difference as low,medium and high load by the load balancing application.Fetching the real time responses of entire servers in the server farm is a key component of this intelligent Load balancing system.Many Load Balancing schemes are based on the graded thresholds,because the exact information about the networkflux is difficult to obtain.Using two thresholds L and U,it is possible to indicate the load on particular server as low,medium or high depending on the Maximum response time difference of the servers present in the server farm which is below L,between L and U or above U respectively.However,the existing works of load balancing in the server farm incorporatefixed time to measure real time response time,which in general are not optimal for all traffic conditions.Therefore,an algorithm based on Propor-tional Integration and Derivative neural network controller was designed with two thresholds for tuning the timing to probe the server for near optimal perfor-mance.The emulation results has shown a significant gain in the performance by tuning the threshold time.In addition to that,tuning algorithm is implemented in conjunction with Load Balancing scheme which does not tune thefixed time slots.展开更多
基金Supported by the National Natural Science Funda-tion of China (60373075)
文摘Distributed Denial of Service （DDoS） attack is a major threat to the availability of Web service. The inherent presence of self-similarity in Web traffic motivates the applicability of time series analysis in the study of the burst feature of DDoS attack. This paper presents a method of detecting DDoS attacks against Web server by analyzing the abrupt change of time series data obtained from Web traffic. Time series data are specified in reference sliding window and test sliding window, and the abrupt change is modeled using Auto-Regressive （AR） process. By comparing two adjacent nonoverlapping windows of the time series, the attack traffic could be detected at a time point. Combined with alarm correlation and location correlation, not only the presence of DDoS attack, but also its occurring time and location can be deter mined. The experimental results in a test environment are illustrated to justify our method.
文摘针对传统瓦斯多级监管系统存在的不足,研究了基于ArcGIS Server Java ADF和JSF框架下的网络地理信息关键技术,构建了ArcGIS server API和Java ADF两种技术集成的开发方案,设计了基于元数据的属性数据分布式存储和空间数据集中部署的数据库存储方案,实现了B/S结构中的浏览器端与服务器端的瓦斯多级监管系统。
文摘目的研究定时作业和多作业协调机制在SQL Server 2005数据库系统中的实现方法.方法采用定时作业和多作业协调机制来有效地优化系统资源,设计基于多定时作业协调方式的管理系统软件及硬件结构方案;使用了两种多作业协调的方法.结果以某大型矿山B/S企业综合系统为例,建立了以多作业协调机制为核心的后台数据库动态管理系统,通过在定时作业中调用存储过程对系统数据库中的数据进行整理、备份、更新和汇总运算,并运用多作业协调机制实现多个定时作业的高效执行.结论工程应用证明在大型数据库系统中,多作业协调机制可以有效地解决数据冗余问题,提高了系统响应速率.
文摘Web service applications are increasing tremendously in support of high-level businesses.There must be a need of better server load balancing mechanism for improving the performance of web services in business.Though many load balancing methods exist,there is still a need for sophisticated load bal-ancing mechanism for not letting the clients to get frustrated.In this work,the ser-ver with minimum response time and the server having less traffic volume were selected for the aimed server to process the forthcoming requests.The Servers are probed with adaptive control of time with two thresholds L and U to indicate the status of server load in terms of response time difference as low,medium and high load by the load balancing application.Fetching the real time responses of entire servers in the server farm is a key component of this intelligent Load balancing system.Many Load Balancing schemes are based on the graded thresholds,because the exact information about the networkflux is difficult to obtain.Using two thresholds L and U,it is possible to indicate the load on particular server as low,medium or high depending on the Maximum response time difference of the servers present in the server farm which is below L,between L and U or above U respectively.However,the existing works of load balancing in the server farm incorporatefixed time to measure real time response time,which in general are not optimal for all traffic conditions.Therefore,an algorithm based on Propor-tional Integration and Derivative neural network controller was designed with two thresholds for tuning the timing to probe the server for near optimal perfor-mance.The emulation results has shown a significant gain in the performance by tuning the threshold time.In addition to that,tuning algorithm is implemented in conjunction with Load Balancing scheme which does not tune thefixed time slots.
