基于ACE的海量三维空间数据通信研究

三维可视化已成GIS发展的潮流,这必然会导致空间数据量的激增,通过集群系统和并行数据库系统可以很方便地解决海量数据的存储管理问题。但是,在海量环境下,一般数据库管理系统提供的查询接口,仍然难以满足实时三维场景可视化的速度需求。因此研究C/S模式下海量三维空间数据的高效调度成为三维GIS发展亟须突破的难点。在数据库服务器端和客户端之间加上应用服务器端,提供数据缓存、预调度等功能,减少服务器端磁盘I/O所带来的时间消耗,可以明显加速数据调度。本文系统分析了这种客户端/应用服务器端/数据服务器端模式下三维空间数据通信的难点和主要设计挑战,并针对三维GIS的数据访问特征,设计了一套能满足三维GIS实时调度的通信应用层协议。以ACE中前摄器框架为基础,结合线程池技术提出分层策略,搭建了海量三维空间数据的通信架构,它是一种面向对象的构架,可以方便地进行功能的定制和扩展。

Study on Communication of Massive 3D Spatial Data Based on ACE

Three-dimensional visualization has become a GIS development trend,and it will inevitably lead to an explosion of spatial data,hence the study on storage and management of massive three-dimensional geospatial data is of great significance.The C/S framework,consisting of database of massive three-dimensional geospatial data for server and a large number of normal PC for clients,has become a basic idea to solve the problem.It is deeply discussed and researched how to realize massive three-dimensional data server related technologies in this paper.Based on analysis of the data dispatch of GIS application thoroughly,a protocol of application layer for high-performance network transmission is designed.The layered strategy that based on the ACE proactor framework and thread pool technology was designed to build a transmission framework for massive three-dimensional geospatial data.The I/O strategy to handle the large-customer communication and the concurrent architecture based on it are discussed.Designed server with modular ideas increases the expansivity greatly.The architecture of the object oriented framework is described in this paper,which supports multiple server policy configurations.Because it is a dynamically ordered structure,it can systematically order these strategies and can statically and dynamically change their behaviors.The framework has solved the transmission problem of multi-level cache and concurrent access problem and realized a highly efficient and stable transmission of massive three-dimensional geospatial data.