GloSDC: A Framework for a Global Spatial Data Catalog

GloSDC is a JXTA-based three-tiered framework for global catalog in grid GIS, which is a mechanism of using P2P model to solve the problem of grid replica organization. We use horizontal non-overlapping fragmentation method to partition a logical layer into physical fragments according spatial extent. A fragment layer is an autonomous layer stored in a grid node, being accessed through node SDE. There are no centralized data dictionary and managing node in the grid spatial database. In order to improve the efficiency, we use R-tree index in fragment layers, quad-tree in fragment catalogs. The lazy release consistency is used to maintain the consistency between secondary and master replicas. The soft-state protocol is used to keep the catalog consistent. Based on concurrent spatial queries, data refinement, spatial analysis and asynchronous rendering, the response latency on clients is reduced remarkably.