XML與關聯式資料庫之間資料模式和查詢語言的轉換互動與績效評估工作量模式設計之研究(2/2)

Abstract

隨著全球資訊網(World Wild Web，WWW，Web)的日趨普及，我們發現愈來愈多的資料是直接從網路上存取。不同於過去關連式資料庫(RelationalDatabase Management Systems，RDBMS)的結構式資料(Structured Data)，現今許多資料是直接以HTML Hypertext Markup Language)格式存取。這些屬於半結構(Semistructured)或非結構式(Unstructured)的資料，我們稱之為超文件/超媒體資料(Hypertext/Hypermedia)。不同來源的資料諸如關連式資料庫和超文件資料，儲存於各自不同的資料庫，且有其各自的資料模式與查詢語言來管理與維護這些資料。面對這些異質(Heterogeneous)的資料來源，我們面臨如何做資料整合(Data Integration)，亦即允許對多元資料來源資料的存取(Multi-Sources Data Access)、資料交換(Data Exchange)，以使不同來源的資料能夠相互運算(Interoperability )，達成異質性資料的同質化(Homogeneity)。更進一步達到多元異質資料來源的可攜性(Portability)、延展性(Scalability)、相容性(Compatibility)與通透性(Transparency)。如何解決這些問題，讓不同來源的資料可雙向的互相溝通，以達到異質資料整合、資料交換和運算，將是本研究主要研究的課題。

With the popularity of WWW (World Wide Web or Web), we have seen massive volume of data emerges on the Web. Unlike traditional data stored in RDBMS (Relational Database Managements Systems) that is structured, Web data now has to be stored in the form of HTML (Hypertext Makeup Language) pages. In addition, in order to represent data and interchange between Web sources, XML (Extensible Markup Language) is fast becoming the dominant exchange standard. Like HTML, XML is a subset of SGML. However, unlike HTML tags only serve the primary purpose of describing how to display a data item, XML tags describe the data itself. The initial impetus for XML may have been primarily to enhance the ability of remote application and to interpret and operate on documents fetched over Internet. XML has become the best solution to resolve these problems with data exchange and transformation between multiple and heterogeneous Web sources. However, XML raises a fundamental research issue, i.e. how to integrate XML documents with the traditional data stored. The objective of this research is to enable the bi-directional data exchange and operation interoperability between RDBMS and XML. Furthermore, the heterogeneous Web data can become portable and scalable. Interchange and interoperability can be reused. In this research, we develop a full transformation between RDBMS and XML. We develop a dual model of XML/RM and XML/SQL interoperability. We develop a set of four components in the method to tackle the research issue. They are (1) data definition transformation (2) data manipulation transformation (3) single document transformation (4) multiple document transformation. A prototype is implemented in this research to prove the feasibility and performance of the new method.