Research And Application Of GIS Services Composition Based On Service Chain

With the development of computer technology and network, GIS which is short for Geographic Information Systems was widely used. In order to improve the application value of the GIS technology, the application model integration in the GIS system has become a hotspot. At the same time, because of the increasing of the number of GIS services, one GIS function may have a number of GIS services which correspond to the GIS function. Therefore, the GIS service selection method which is based on the Quality of Service has become one of the key points in service composition.There are some problems in integrating application model into GIS system, such as redundancy, difficulty to reuse the model and so on. To solve those problems, this paper proposes a method. At first, the GIS application model is decomposed into sub-models, and these sub-models and GIS functions are defined as services which are provided to users. Then it defines the QoS of the GIS services. Next, it introduces service chain to the model library, and creates model library which is based on service chain. At the same time, this paper proposed the composition service selection mechanism which is based on modified adaptive genetic algorithm, the mechanism compared with the existed mechanism is easier to meet the needs of users.This paper has completed the major work:①Analyzed the current technology of the Web service and the Web composition at home and abroad, researched the technology of the GIS system and Web GIS services, and analyzed the advantages and disadvantages of the existed GIS system application.②Studied the technology of the GIS service chain and the GIS application model, analyzed the characteristics of GIS service, defined the GIS services'type, and researched the GIS service composition based on the GIS service chain.③Created the model library which is based on service chain, decomposed the GIS application model with a top-down approach, defined the model library, provided an alternative model for the GIS services composition.④Analyzed the existed GIS service selection method, used the modified adaptive genetic algorithm to achieve the service selection mechanism which is based on service chain, provided service selection mechanism for the GIS service composition.⑤Designed and implemented a campus navigation system based on GIS services composition. According to the requirement of the campus navigation system, designed and implemented the model library module, the service discovery module and the service composition module. The results of application proved the rationality and feasibility of the GIS service composition process.