Research On Workflow Application For Geographic Information Service Chain

The development of geographic information system can not get away from the IT technical push. By introducing advanced IT technique and theories into this domain, the geographic information system then can be continuously creative. The Web service is that one which studies for the last few years is a little bit hot, after inducting service method to the geography information system, the geographic information service then becomes one of the most important development directions. Along with the extensive application of network, geographic information service's deployment on the network will become more convenient. Generally speaking, one geographic information service can provide single function, so for completing complicated mission related to geographic information, has to combine with several distributed geographic information service, the service chain is put forward for working out this problem. The service chain is divided into transparent chain, translucent chain and opaque chain, among them, the translucent chain is the most vivid, which adopts workflow technique. It not only provides a visual mean to model the service chain, but also adjusts the performance of service chain process, which carries out combining services dynamically. Currently, for the research of service chain, mainly concentrated on the detection and description of service, but the research of workflow technique which is suitable for the geographic information service chain is less investigated. So according to the above consideration, the research point of this paper is put on the workflow technology which is applied to the domain of geographic information service chain.Firstly, this paper analyzed the foundation knowledge of the geographic information service chain, which included three aspects. One is the Web services and its architecture and the service-oriented WCF programming model that was lately-released by Microsoft; Two is the workflow technique, including related concept and theories, and the advantage which was bring by combining workflow with Web services; Three is the geographic information service, including related concept and classification, finally analyzed and compared three kinds of appearances of the geographic information service chain, based on which established translucent chain as this paper's research contents.Secondly, research was set to the workflow technology which is suitable for geographic information service chain and included two sides: One is the service chain process modeling which included modeling method and process define language. With analysis of popular modeling method at present, this paper carried on an enlargement to the Activity Network Graph, which could satisfy the service chain modeling need; In the aspect of process define language, this paper defined a describe language GCPML(the Modeling Language of the Chaining Process of the GI-Service, brief name GCPML), which can expediently describe the process language of service chain righteousness; In the end designed a modeling tool. Two is the design of workflow engine, which is the workflow's core technology. This paper drew lessons from SOA(the Architecture of the Service Oriented)"triangle" structure to design the architecture of the workflow engine with the solution of geographic information problems that are the huge data and data with different formatter; Finally work were carried on to engine adjusting arithmetic and the design of application framework.This paper finally designed a workflow management system for service chain, which mainly included two functions: service chain modeling and engine execution, and achieved the targets of visual combination of geographic information services and the chain's automatic performance.