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Return to Tutorials XML is being used in different application scenarios: XML has established itself as the standard for information exchange over the Web, and applications over the Web use XML for representing their information XML is used for publishing data of traditional database applications as well as text applications over the web XML is being tried as a logical data model: here, people come up with a conceptual model for database applications, and translate this conceptual model into logical XML model; the XML model might be stored in native XML databases or relational databases, XML promises to be a good candidate for federated databases to provide a uniform view of multiple data sources. Our tutorial will cover two application scenarios of XML: using XML as a logical model, and publishing relational data as XML. First, we will study how we can use XML as a logical model. We will describe the various options for structural specification for XML such as DTD, XML-Schema, RELAX NG, and also different options for constraint specification for XML such as XML-Schema and other research proposals. We will further describe the stages in the database design process -- coming up with a conceptual schema from real world applications, translating this conceptual schema into a logical schema, and translating this logical schema into physical schema. A conceptual schema is specified in a conceptual data model, such as ER, ORM, or UML. We will compare and contrast the important features of these conceptual models. We will then propose some extensions to ER model, and use this as our conceptual model. We will describe how a conceptual schema can be translated into logical XML schema and give examples. We will further describe what structural and constraint specification features are needed for using XML as a logical model. In the second half of the tutorial, we will describe translation between XML and relational models. We will cover different options for translating XML to relational and study existing systems in this regard. ![]() ©2005 Association for Computing Machinery |