一种基于地理单元热度的瓦片缓存策略.pdfVIP

90 2017 ，53（5） Computer Engineering and Applications 计算机工程与应用 一种基于地理单元热度的瓦片缓存策略 刘佳星，陈飞翔，陈星涵 LIU Jiaxing, CHEN Feixiang, CHEN Xinghan 北京林业大学 信息学院，北京 100083 School of Information Science and Technology, Beijing Forestry University, Beijing 100083, China LIU Jiaxing, CHEN Feixiang, CHEN Xinghan. Tile cache strategy based on geographic unit heat. Computer Engi- neering and Applications, 2017, 53 （5 ）：90-96. Abstract: As for the problems that server and network have too much pressure and response time is too long during the data transmission of tile, cache mechanism has been established in client side, cache index of tile has been constructed and a tile cache replacement method named Geographic Unit Heat （GUH ）has been proposed. The algorithm is based on the smallest geographic unit of tile, which integrates the zoom level of tile and the heat of geographic location, and utilizes heat volatile to adapt to the temporality of tile cache. On the basis of this method, the heat value and cache space have been abstracted into 0/ 1 knapsack problem and the solution is solved by ant colony algorithm. The results of experiment indicate that this algorithm has significant increase in tile hit rate and byte hit rate. Key words: cache policy; geographic unit; zoom level; heat; tile 摘 要：针对瓦片数据传输时造成的服务器与网络压力过大、响应时间长的问题，在客户端建立缓存机制，构建瓦片 缓存索引，提出了瓦片数据的GUH 缓存替换算法。该算法基于瓦片最小地理单元，融合了瓦片的缩放层级和地理 位置热度，并利用热度挥发适应瓦片缓存的时间性。在此基础上，将热度价值与缓存空间抽象为0/ 1 背包问题，并通 过蚁群算法进行求解。实验结果表明，该算法在瓦片命中率和字节命中率方面有显著提高。 关键词：缓存策略；地理单元；缩放层级；热度；瓦片 文献标志码：A 中图分类号：P208 doi ：10.3778/j.issn. 1002-8331.1608-0530 1 引言 种按需获取服务的方式避免了不必要的空间数据传输， WebGIS （网络地理信息系统）是地理信息系统和 使得服务器和网络传输的负担得以减轻。 Internet 结合的产物，其诞生改变了地理信息的获取、传 在大数据时代背景下，用户规模的持续增长造成的 输、发布、共享和应用方式[1] ，已深入人们的日常生活。 访问量剧增和瓦片地图数据自身的海量特性使得网络 传统的WebGIS 系统是通过客户端向服务器端发送带 地理信息服务依然面临网络阻塞和服务器过载等问 有区域位置信息的请求，根据请求实时生成目标区域的