وتطبيقاتهـــــــــا في التعليــــم الإلكتروني XML تقنيــــــة قواعــد بيانــات

XML Databases Technology and Its Application in E-Learning

Department of Mathematics. Faculty of Science. Helwan University"     

                                "XML (eXtensible Markup Language) has become a standard format in information exchange and integration on the Web. Much research has been conducted in recent years on XML technology, which has led to new developments in this field. One of these developments is XML Database, which is meant for efficient management of XML data. While it is possible to store XML data in traditional relational databases or object-oriented databases, we also desire high-performance native XML databases that are particularly tailored for XML data.

                This dissertation introduces mainly three issues needed to support the XML databases:

[1]          We introduce a novel approach for storage and retrieval of XML documents using relational databases. Our approach enables us to store XML documents using a fixed relational schema without any information about XML schema. For the processing of XML documents, we propose two algorithms, the first, for converting XML data to relational data, and the other for extracting data from database tables and create the XML document corresponding to it. Our approach doesn't assume any extension to the relational model, and no restriction should be imposed on the input XML documents.

[2]          We study the problem of how to extend the concepts of functional dependency (FD) and normalization in relational databases to include the XML model. We show that, like relational databases, XML documents may contain redundant information, and this redundancy may cause update anomalies. Furthermore, such problems are caused by certain functional dependencies among paths in the document. Our goal is to find a way for converting an arbitrary XML Schema to a well-designed one, that avoids these problems. We first introduce new definitions of FD and normal forms of XML Schema. We show that our normal forms are necessary and sufficient to ensure all conforming XML documents have no redundancies. Finally, we present the decomposition algorithm for converting any XML Schema into normalized one, that satisfies X-BCNF.

[3]          Based on the XML databases technology, and relational databases, we developed an easy to use web-based training and quizzes system. The system allows teachers to store, update, and delete questions from the database using the web, in a very easy and simplified manner. In addition, teachers can track the activities of their students and can guide them to reach the pre-determined objectives of the courses. Our system is used successfully in distance learning as well as in self-training. We have tested the system with different type of courses taught in the university. The feedbacks of both teachers and students were highly promising.

Based on the previous work, we introduce the Semantic Web-Based model for our e-learning system. In addition we introduce an approach for developing a Semantic Web-based e-learning system, which focus on the RDF data model and OWL ontology language.

Keywords: XML, XML Documents, XML Schema, XML Data Conversion, XML Databases, Relational Databases, XML Databases Design, Functional Dependencies, Redundancy, XML Normalization, Normal Forms, Educational System, WBT, E-Learning, Distance Learning, Semantic Web, RDF, Ontology, OWL."