The Research Of Several Important Problems In GIS Service Sharing System

GIS has combined the geography information and videotext. It is regarded as one of the most important businesses in 21 century. But in the development, there are many kinds of GIS. All of them have different data formats and they can't make use of each other, it has restricted the development of GIS. Although OGC appeals to use web service to solve this problem, it is not solved completely.This paper firstly introduces the development history and research technology of GIS, then goes deep to the problems that have restricted the development of GIS. The main content of the paper is:1. Research on web service description. The web agent marked language (WAML) is put forward as the GIS service describe language. The relation between each parts of the WAML is described. OWL in WAML is used to describe the ontology of WAML. Child-brother tree is used for describing sibling classes. WAML can describe service description better.2. Research on extending service description ontology. Ontology extending is based on concept tree by the character of tree. During the extending, the complexity and conflict of the ontology are taken into account. The complexity of the ontology is calculated by the depth and width of the concept tree. Ordinary conflicts settle method is put forward. It is shown in experiment that ontology extending can increase the search results.3. Research on service description matching. Concept tree and vector space are used in service matching. Concept tree is used in calculating the concept distance in the same tree. By combined with vector space, it can calculate the distance of different keywords in different trees. In experiment, more and better results are got in service description matching.4. Research on service combination. The method of using the semantic WAML to generate a web service chain is put forward. Firstly the arithmetic of service combination is present, then the Dijstra arithmetic is used to get the best route, At last several problems such as loop and graph modifying are solved. It is proved the combination arithmetic can provide the user useful service chains.5. Research on GIS service sharing system. Multi-agent is used to combine the parts of GIS service sharing system. Firstly the structure of GIS service sharing system is discussed. Model and cooperate method are introduced, and then the communication language and communication method based on SOAP are worked over. It is proved in experiment that communication method based on SOAP can satisfy the user. By using agent, the system can run more quickly and more strongly.A GIS service sharing system is realized in the last chapter of the paper. By this way, our research is proved to be correct. Firstly the method to implement every agents is put forward, then several GIS subsystems which will be used in GIS sharing system are realized, and the services of subsystems are introduced, at last an ITS subsystem based on service sharing is introduced.