Research On Method Of Distributed Geographic Information Service Chain Construction Based On OGC Standard

The development of geographic information has shifted from the limitation of spatial data to the limitation of data analysis and processing functions.The development of computer technology,especially network technology,has solved the problem of data sharing in the field of geographic information.It has become a research hotspot to solve the limitation of data analysis and processing function with the help of the idea of Web services.Through the functions of data acquisition,processing and analysis from the network,we can integrate multiple geographic information service resources to accomplish complex tasks,and move from single geographic information service to service chain mode of multi-service collection.By analyzing the current research status and standard specifications of geographic information service,this paper explores the construction method of distributed geographic information service chain with the help of workflow technology.User-oriented application model of geographic information service chain is developed based on the case model of torrential rain and flood disaster.This research mainly includes the following parts:(1)Research on geographic information service technology and specification.Based on the principles,architecture and key technologies of Web services,the related contents of geographic information services are introduced.Starting from the concept of geographic information service,through the comparative analysis of the classification system of geographic information service proposed by ISO/TC211 and OGC organizations,it is determined to adopt the open standard of OGC as the service specification.Then the standard interface of geographic information service under the standard of OGC is studied.(2)Research on workflow technology.Explore workflow technology including workflow management system and workflow model description language.The composition and functions of workflow management system are analyzed to provide theoretical guidance for the realization of geographic information service chain.BPEL language is used as the implementation of business process description in service chain.The composition and characteristics of BPEL language are analyzed.Activities and controls in BPEL modeling process are studied.(3)Research on the construction of geographic information service chain.This paper analyses the concept and classification of geographic information service chain,compares three types of service chain(transparent chain,opaque chain and translucent chain),and explores the dynamic construction method of service chain.The example of geographic information service chain modeling is analyzed by storm flood model.The process of extracting and modeling rainstorm and flood depression is designed,the deployment process of geographic information service used in the example is clarified,and the service required for publishing the environment of GIS server is built.By introducing Apache ODE workflow engine and Axis service technology,the Axis service adaptation middleware algorithm of OGC geospatial service is designed,and the service chain of depression recognition in storm flood model is designed based on BPEL workflow model.(4)Design a user-oriented test system.Based on the analysis of the application of geographic information service chain,a user-oriented test system is designed and implemented.The service chain of storm and flood model is integrated into the system,and the system is displayed and tested by actual user operation.The experimental results show that the implementation of geographic information service chain oriented to geo-modeling process is effective and feasible,which provides theoretical support and practical guidance for Geo-Information resource sharing in distributed environment.The research shows that following the OGC standard,supporting aggregation and redistribution of various GIS platform services ensures the universality of geographic information services.Business description standards based on BPEL workflow technology support ensure the standardization of service chain description and the dynamic composition method is helpful to obtain new geographic information data and geo-modeling analysis model.The practical geo-modeling and analysis process verifies the feasibility of the above research methods.Using OGC service open standards and workflow technical specifications,the flexible integration and interoperability of geospatial data and advanced analysis model of GIS in distributed systems are promoted,and the application model promotion based on geographic information service chain is realized.The practical problems of low utilization and lowscalability of distributed geographic information resources would be fully solved.The breakthrough transformation of geographic information from "information isolated island" to distributed sharing would be realized.The collaboration of experts in multi-disciplines and multi-fields would be promoted,and the theoretical and methodological system in the field of geographic modeling would be enriched.