RESEARCH AND IMPLEMENT OF GEOSPATIAL PORTAL BASED ON GRID AND AGENT
J.Y. Wang, M.G. Wu, Y. Cheng
Institute of Surveying and Mapping,ZhengZhou,China
The concept of Spatial Data Infrastructures (SDI) and National Spatial Data Infrastructures (NSDI) are becoming popular in the geographic information community rapidly. The main resources and services delivered by SDIs(NSDIs), such as geospatial data discovery, accessing and processing are highly valued by the community. However, the lack of technical and institutional utilities to support access to datasets and services available in distributed heterogeneous systems poses challenges to support the geographic information users.
A Geospatial portal is a single point of access to spatial information, regardless of the location, format, or structure of the data source. A Geospatial portal is also a gateway of access to distributed geographic Information services. And it also makes it easier, faster, and less expensive. It enables geo-processing interoperability and makes it possible to exchange heterogeneous geographic information content and share a wide variety of geospatial services delivered by SDIs(NSDIs).
The Grid and agent communities both develop concepts and mechanisms for open distributed systems, albeit from different perspectives. Grid technology provides secure, fundamental methods for advanced distributed computing and data sharing over the Internet. However, the Grid Services offered by Open Grid Services Architecture (OGSA) and Web Service Resource Framework (WSRF) are somewhat rigid and inflexible on service host. The mobile agents can offers maximum flexibility by moving code or data into optimal places.
This paper is an effort to design a dynamic geospatial information service and integration framework by making use of both Grid computing and agent based computing technologies to server Geospatial Portal.
Firstly, a new concept of dynamic geospatial information service base on Grid and Agent is proposed for distributed geospatial information service. The geospatial information service can take full advantage of Grid and Agent, overcome the disadvantages of existing Geographic Information System and current service integration model.
Secondly, the integration framework of dynamic geospatial information service is put forward, which includes service stack, service chaining patterns and service integrating model.
Thirdly, this paper proposes an implementation method of dynamic geospatial information service chain based on workflow technology. This method uses dynamic geospatial information services composing geospatial information service chain. The dynamic services can be port to concrete geospatial information services by dynamic service finding and relocating mechanism. Combined with workflow technology, the process of GIS service chain described by workflow description language can be sent into geo-workflow engine to be executed and monitored in the Geospatial Portal.