Research On Key Technologies Of Policy-Driven Cooperative Composition For Geospatial Information Services

Service mode of geographic information are effected by developed applications of geospatial information network significantly. Therefore, recently the national surveying and mapping bureau of China has granted research projects such as "Geographic information public service platform" etc. to enhance the capacity and level of geographic information service. Nowadays, due to the complexity of the web environment, techniques of Web-based geospatial data sharing and interoperation services still facing several common problems e.g. service semantic ambiguity, lack of dynamic and flexible service composition, service exceptions are difficult to dispose etc. Furthermore, regarding to the initiative discovery and flexible management of distributed collaborative service resources, no reliable and well developed methods or products are available, which impedes the applicability of geospatial data/resources sharing and interoperation services.A two-level geospatial information service collaborative model namely Geospatial E-Institution& Geospatial Agent Model (GEI&GAM) is proposed in this thesis by integrating achievements from four related techniques i.e. services computing, autonomic computing, policy management, and OGC geospatial information service specification. After studying the cooperative control guidelines and application management policy set for the service collaborative environment, methods of macroscopic regulation and control are investigated. These methods cover from abstract service process description of geospatial e-institution to the service chain implementation of specific geospatial agent. Then, control model of geospatial e-institution and specific implementation mechanisms of geospatial agent is established to form the loosely coupled two-level service coordination system. Finally, on-demand automatic creating and independent evolving for geospatial information services coordination are achieved to satisfy the dynamic, flexible, fast, effective and safe applications of geospatial data sharing and interoperation. The main research works are as follows:1. A two-level geospatial information service collaborative model GEI&GAM is proposed after studied distributed collaborative framework. Shared ontology of collaborative geospatial information services and cooperative reasoning rules to provide semantic foundation are established. Based on shared ontology, representation method of services collaborative management policy is also introduced.2. Research on cooperative control model of geospatial e-institution is conducted; and business specification template of collaborative geospatial information services described in the way of the geospatial e-institution is established afterwards. Besides, policy-driven self-management mechanism of geospatial agent is studied based on techniques from software agent, composite structure and its internal components collaborative method and external configuration of geospatial information service.3. According to the collaborative service model of GEI&GAM, link mechanism between macroscopical business objectives of geospatial e-institution and individual behavior of geospatial agent is studied. By means of policy-driven self-management, collaborative acts of geospatial agent is macroscopical regulated. Followed the development of cooperative control guidelines and application management policy set of the service collaborative environment, control model of geospatial e-institution and specific mechanisms for implementation of geospatial agent are established, and loosely coupled system of two-level service coordination is formed.4. Distributed geospatial information services collaborative architecture prototype based on GEI&GAM is designed, and an application of the prototype is given to verify the effectiveness of the infrastructure.The results show this proposed GEI&GAM collaborative service model, which combines techniques from semantic ontology, Agent, policy management and OGC geospatial information services is able to provide intelligent, automated distributed collaborative processing capability for geospatial information. Using shared ontology, geospatial e-institution is able to establish geospatial model and abstract geospatial information collaborative service process; besides using policy-driven self-management, geospatial agent is capable of following the process of geospatial e-institution to form geospatial information service chain on demand, and monitoring/handling exception of service coordination. This loosely coupled two-level system promotes intelligent expression and flexible management of geospatial information service, and lessens human intervention. It also provides a new way for geographic information public service platform in the loose coupling integration, dynamic assembly and management of service resources.