The distribution of GIS data is achieved, and the goal of middleware-based grid is to achieve the distribution of data and functional services. This article introduces the information processing process of the grid, and proposes an implementation strategy for grid data transmission based on the requirements of the grid for data transmission functions. In the process of grid data transmission, the description of geospatial data information is completed through language, and grid data transmission services are constructed using , , message middleware, etc. At the same time, security issues in grid data transmission are discussed. Elaborate, use the proxy mechanism to complete security control during data transmission.
WebGIS realizes the sharing and distribution of geospatial data resources. Typical WebGIS is mainly implemented through centralized mode, that is, geospatial data collections are stored on one or several data servers (computers), and remote users (client computers) realize remote calls to these data resources through network connections. For WebCIS with B/S structure, resource processing is mainly concentrated on the geographic information function server. For CS structure, the server and client share different computing operations. This implementation method increases the burden on the server. With the development of computer technology and network technology, users’ demand for geographical information will be greater, but the processing capacity of the server is limited; at the same time, customers’ frequent calls to data resources are Data requests are sent to the data server through the function server, and the data operation is performed by the data server. This greatly increases the utilization of the network and consumes a large amount of network resources.
Traditional WebGIS only realizes the sharing and distribution of data. As GIS users increase their GIS processing capabilities and information exchange speed, WebGIS seems to be inadequate.Current GIS software
Software such as ArcInfo and MapInfo are highly integrated software. Users must learn the functional structure of this software when applying it.
structure, and requires users to have a considerable level of GIS professional knowledge. At the same time, users must purchase this system when purchasing these software, and cannot purchase certain functional components.These problems cannot be solved by WebCIS
To solve the problem, grid GIS based on middleware can not only provide users with efficient computing and processing functions, but also middleware grid GIS can publish GIS services. Users can find the functional services they need from the network and submit them for processing according to their own needs. command to obtain the required processing results.
2 Grid GIS analysis based on middleware
Middleware is a type of software between application systems and system software. It uses the basic services (functions) provided by system software to connect various parts of the application system or different applications on the network, and can achieve resource sharing and function sharing. the goal of.Middleware has the following characteristics:
(1) Standard protocols and interfaces;
(2> Distributed computing provides network, hardware and operating system transparent performance; and can meet the needs of a large number of applications; runs on a variety of hardware and operating system platforms.
What middleware brings to GIS application systems is not only the simplicity of development and the shortening of the development cycle, but also the workload of maintenance, operation and management of the GIS system, and the overall computer cost investment. Middleware serves as a new level. The important role of the basic software is to integrate GIs application software developed on different operating systems in different periods. This is something that the operating system and GIS database management system itself cannot do.Middleware is divided into 3-6 according to functions; data
Access middleware (Data Access Middleware), remote procedure call middleware (RPC Middleware), message-oriented middleware (MOMiddleware) and transaction processing middleware (TP Middleware), etc.