| Extensible Markup Language (XML) can not only depict the structural data, but also efficiently describe the semistructured data, even the non-structural data. This leads a widespread application of it on the web data management. On the other hand, the technique of XML has obvious deficiencies on the management. As we all know, the majority of users are only interested in a certain part of it, while there is no similar concepts of the external pattern between XML and RDBS. DTD (Document Type Definition) is usually regarded as the data model of XML. In the XML document, how the data in document has been organized and kept is depicted through the use of DTD. However, the effectual resource DTD has not been made best of it in the present query technology. By far, the function of DTD is only to provide a valid verification for a "well-founded" XML doc. Therefore, it is an effective way to implement the requests of query and management for different users and to simplify query process.Based on the above cognitions, a solution has been put forward in the thesis that is used to realize an information query of the XML doc modularization based on the DTD syntax tree. The main idea of the solution is to add the coding information of mark module by extensible DTD doc to finish extracting the subschema from DTD. Accordingly, it can create the XML query program on the basis of the subschema so that it can carry out the quest to query the data in the XML model.This paper mostly solves the following problems:1) First of all, the thesis aims to extend the XML doc aims at the diverse query requests of users. In order to fulfill the query request of different users by constructing a query interface, it needs to form the elements in DTD into several different BCMs by adding extensible mark to the element layer. It can also conveniently construct the index between the query interface and BCMs so that users can quickly extract the depiction of the DTD in the user's query pattern.2) Secondly, the thesis aims to finish the self-creation of the XQuery based on DTD. In this thesis, we try to study how to form the storage structure and the path index structure of the DTD tree which founds on the DTD tree model. We will also try to find the method of expression to self-create XQurey FLWR through the path index. 3) Implementation of the prototype system. There is a prototype system of XML query based on the extensible and modularized DTD. It has completed the self creation of XQuery FLWR expression based on the extraction of the DTD depiction of BCMs, and has validated feasibility of the technology of the solution.In contrast to other XML information query system, the query technology of this modularization has the advantages as following: 1) it has the access information of all XML docs on the Internet; 2) it is more convenient and faster for users to take the modularized query method to skim through XML docs; 3) it can availably decrease the loaded quantity of clients and it more adapts to the mobile users and dial-up users. |
