Research On Spatial Information Specialized Search Engine Based WEB Services

Spatial information specialized search engine allows user to access distributed spatial information directly ,and is a new research area in the field of spatial information integrating and sharing. This paper makes in-depth theory research and system design about technology of Spatial information specialized search engine based web services.Firstly ,this paper introduced the technology of traditional spatial information integrating and sharing,and introduced the conception of spatial information service (OGC web services) recommended in OGC(Open GIS Consortium) Spatial Information Reference Architecture. After comparing general web information retrieval and online spatial information retrieval,a Spatial Web Service-based dynamic spatial information search engine is discussed.For dynamic discovery of online OWS (OGC Web Services) instances, this paper put forward a algorithm based on "Capabilities document" extraction.The algorithm is based on spatial information wrapper rules and syntaxes,which may effectively improve the recall and precision of geo-spatial service discovery process.For designing and implementing Chinese words segmentation module in the search engine based on Nutch.this paper put forward a algorithm based on forwards maximum match algorithm (MM). The algorithm is to extract the keys from OWS Capabilities document,and add new word to dictionary, which has favorable eficiency, recall ratio, and accuracy. For the relativity judging between Spatial information content and topic , this paper put forward a advanced ordering algorithm based on TF*IDF algorithm.The algorithm apply the term-based vector space model,which is vital to improving the relevance of the searching results and enhancing user satisfaction.Finally,we develop a prototype system of Spatial information specialized search engine based on OGC web services to verify the idea. Furthermore,the detailed function of each component such as wrapper,Analyzer,indexer and Searcher are introduced. The system accomplish primal research and target on the whole.