Prefetch policies for large objects in a Web-enabled GIS application

In a Web-enabled geographic information system (GIS) application, it would be possible for users to navigate existing spatial objects (e.g.. points, l ines) or spatial query results containing large objects (e.g.. raster image s, Web documents) on the Web browser. For efficiency, relatively 'light' sp atial objects exist on the Web browser, while 'heavy' real information like large objects resides in the remote server. Only when the users callback r eal information for a certain spatial object, the server transmits it to th e browser. In this paper, we propose several prefetch policies, especially the Hillbert curve-based ones which can alleviate user response time under the assumption that user callback access pattern has spatial locality. We c onducted diverse experiments to show that our prefetch strategies based on the Hillbert curve achieve higher efficiency than the other naive or no pre fetch ones. (C) 2001 Elsevier Science B.V. All rights reserved.