Design And Implementation Of The Composition Engine For Geospatial Web Service Based On Workflow

With the increasing requirements of spatial information application, the problems such as huge amounts of distributed spatial data, heterogeneous spatial data format and complexity of spatial data processing, become obstacles of sharing and integration of spatial information. Geospatial web service technologies efficiently resolve the sharing and interoperability of distributed and heterogeneous spatial information. With the enrichment of geospatial web service, it is an important pattern for sharing spatial information to dynamically integrate various existent geospatial web services and form a new value-added geospatial web service. So the technology of geospatial web service composition has been a new pop research area. In this thesis, our research focuses on these technologies, especially the design and implementation of an engine for geospatial web service composition based on the workflow technologies. The main contributions of this thesis are as follows:1. A workflow-based composition framework for geospatial web service is presented. The thesis studies the characteristics of the normal workflow reference model, the application and interoperability framework of geospatial web service, and then the thesis defines a reference model for geospatial web service composition, which provides a holistic framework and a top-level guidance for further studying geospatial web service composition.2. An analysis and design of the geo-spatial web service composition engine is studied. The thesis firstly studies functions of the engine. In the engine, this thesis uses a process to model the geospatial web service composition. So in those functions there are four aspects, namely, the process description, the process scheduling, the process implementation and the process interface. And then this thesis probes into the four aspects and using a process description model to analyze the process description, a control model to analyze the process scheduling, and a state transition model to analyze the process implementation respectively. Finally, this thesis designed an architecture for the engine.3. An implementation of the geospatial web service engine is given. Base on the architecture, this thesis studies a realization of the architecture's modules. In those modules there are some core modules, such as the process interface, the process scheduling and geospatial web service invocation. This thesis studies those core modules in detail.4. A representative application for the service-oriented mineral resources assessment is designed and implemented. This thesis uses some geospatial web services to compose components for the mineral resources assessment process with an experiment. The successful experiment shows that our engine can do well in some applications with an underlying geospatial web service environment.