Research On Semantic Web Model For GIS Of Changchun City

The Semantic Web technique is one of the investigation hotspots in current Internet research. It provide a series of new technologies to change the mode that the current Internet only depend on the literal information to share the resources. Its target is to define,connect a web which is not only to show content (to men) in function but also enable computers automatically operate ,integrate and repeatedly use the whole resource in web as best. In computer science the ontology refers to the representation of a shared conceptualization of a particular domain. The researchers of the Semantic Web technology put forward to add the ontology layer in the construction of the Semantic Web. The ontology layer represents the meaning of the information and the relations of all kinds of semantic information. The semantic information of the Semantic Web is based on the ontology and also represents exactly in ontology. Through this way, every agent in the Semantic Web can get the share of the semantic level by exchanging ontology. The ontology layer provides the vocabulary set in communication. Thus the construction of the ontology layer is the key of the Semantic Web technology and became a hotspot of the research interest. This paper makes a investigation about the representation of ontology and the construction of the ontology layer in the Semantic Web. Based on this investigation we put forward a way of describing oriented graph of ontology in XML. XML (Extensible Markup Language) is a meta language of tag language. It allows you according to its rule to establish all kinds of tag languages. Today, XML is already applied extensively to data expression in the Internet and data swap between different systems. All sorts of packages operating the XML documents have been developed. The documents described by XML can usually be organized to a tree form. This paper uses XML to describe the ontology while representing it. In the ontology, the contact of the concepts can be in token of a kind of net structure. Like this, the description ability of XML has some limitations. So we provide "acr"link to describe the connectedly relationship between nodes of different subtree in the tree form of XML document. "arc"is a element of XML,a empty element,its meaning and format is fixed,it represents the link of oriented graph, there are three attributes in "arc",the attribute of "name"is to represent the name of the link, the attribute of "from"is to represent the originating point of the link, the attribute of "to"is to represent the end point of the link,the link can describe the relation between the elements in the same XML document or the different one.We can use the element of XML document to represent the resource,so the "arc"can represent the relation of the resources.when we describe ontology in XML the element of XML document can be represent the concept in the specific domain and the "arc"can be represent the relationship of the concepts.In this way,we can describe the net structure in the ontology as a oriented graph. The system is a semantic model oriented geographical information domain,so after oriented graph description represent the ontology,the logic layer basing on ontology layer adopt the classic path searching algorithm in GIS--E.W.Dijkstra. The model adopt systematic structure of N layers.display,data,logic are apart,and ontology layer and logic layer are apart.Each layer is extensible,so each layer can be added,deleted,edited and so on. The datum of ontology is stored in information database that is made up of a lot of XML documents.The model first get the concept set and the relationship set of ontology through parsing the XML document by XML DOM,then exactly find the real concept or relationship.when we reffer to concept alignment problem the attributes of element of XML document may be very useful The characteristics of the domain in the model are mainly taken into account in the constructing of logic layer.The classic path searching algorithm in GIS is E.W.Dijkstra algorithm which need the specific data structure in perform,so there are two basic tables of GIS are required in the model,one is table of nodes information,the anther is the table of arcs information,they both are store in a relation data base. Trust layer in the model is simply designed as a permissive mechanism.When data access to ontology layer,the model can automatically parse XML document to discern the concepts and relationships in order to display them to administrator.The administrator can decide whether to permit data access to ontology layer,and when the data in ontology layer access to...