In recent years, several results have been introduced to enhance distributed GIS performance. While much more efforts have focused on tile map and simple symbologies on dynamic map, load balancing GIS servers have not...In recent years, several results have been introduced to enhance distributed GIS performance. While much more efforts have focused on tile map and simple symbologies on dynamic map, load balancing GIS servers have not been addressed by the GIS community so far. This paper, therefore, proposed dynamic distributed load balancing for D-GIS in order to quickly render information to client interface by involving a set of GIS servers which process clients’ requests depending of an algorithm. In the model, several concepts were introduced and defined: Virtual Server within physical machine which constitutes a setup environment for a single GIS server, Load Hash Table which contains information about virtual server’s capacity, real-time load and other mandatory elements, Request Split Table which splits requests depending of the input area’s Quantity of Information and stores request tasks composition for later reconstitution. At last we have Distributed Failover Callback Function Table level one (respectively level two) which determines whether or not the request had been successfully processed by the chosen virtual server (respectively physical machine). This table allows sending back the same request to another virtual server (respectively physical node). Two load handlers (primary and secondary) are defined in case of failure. Our Model achieves efficient load balancing by: providing efficient node selection;optimizing request routing;managing node failover;involving client’s request partitioning and introducing method type decomposition. A simulation of the algorithm shows a low response time when performing GIS operations.展开更多
林业信息管理和服务涉及不同层次的林业管理和业务部门。目前基于全国的林业互联信息管理服务应用系统还未建立健全。为有效实现林业系统内信息基础设施、信息系统开发、信息系统应用和系统数据的整合以及林业行业上下级之间、各部门之...林业信息管理和服务涉及不同层次的林业管理和业务部门。目前基于全国的林业互联信息管理服务应用系统还未建立健全。为有效实现林业系统内信息基础设施、信息系统开发、信息系统应用和系统数据的整合以及林业行业上下级之间、各部门之间信息服务的无缝有机组合,基于软件即服务的理念,从林业管理、业务服务和技术实现等层面,提出一个多层分布式林业信息服务平台的构建设想。该平台是一个3层架构体系:信息数据层、业务服务层和信息表现层。提出了基于XML Web Service建立林业业务服务的方法与步骤,以及多层次多用户端的B/S与C/S相结合的林业信息服务应用模式。展开更多
文摘In recent years, several results have been introduced to enhance distributed GIS performance. While much more efforts have focused on tile map and simple symbologies on dynamic map, load balancing GIS servers have not been addressed by the GIS community so far. This paper, therefore, proposed dynamic distributed load balancing for D-GIS in order to quickly render information to client interface by involving a set of GIS servers which process clients’ requests depending of an algorithm. In the model, several concepts were introduced and defined: Virtual Server within physical machine which constitutes a setup environment for a single GIS server, Load Hash Table which contains information about virtual server’s capacity, real-time load and other mandatory elements, Request Split Table which splits requests depending of the input area’s Quantity of Information and stores request tasks composition for later reconstitution. At last we have Distributed Failover Callback Function Table level one (respectively level two) which determines whether or not the request had been successfully processed by the chosen virtual server (respectively physical machine). This table allows sending back the same request to another virtual server (respectively physical node). Two load handlers (primary and secondary) are defined in case of failure. Our Model achieves efficient load balancing by: providing efficient node selection;optimizing request routing;managing node failover;involving client’s request partitioning and introducing method type decomposition. A simulation of the algorithm shows a low response time when performing GIS operations.
文摘林业信息管理和服务涉及不同层次的林业管理和业务部门。目前基于全国的林业互联信息管理服务应用系统还未建立健全。为有效实现林业系统内信息基础设施、信息系统开发、信息系统应用和系统数据的整合以及林业行业上下级之间、各部门之间信息服务的无缝有机组合,基于软件即服务的理念,从林业管理、业务服务和技术实现等层面,提出一个多层分布式林业信息服务平台的构建设想。该平台是一个3层架构体系:信息数据层、业务服务层和信息表现层。提出了基于XML Web Service建立林业业务服务的方法与步骤,以及多层次多用户端的B/S与C/S相结合的林业信息服务应用模式。
