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The powerful table-row-column of the relational model is widely accepted as the most effective mechanism for managing structured data. The relational metaphor is not so effective when it comes to managing unstructured data that can be represented as XML documents.
With Oracle XML DB, it is possible to have your cake and eat it too, at least to an extent: You can store your document as an XMLType in Oracle's XML DB repository, which will preserve byte-by-byte document fidelity and also shred it into a SQL table, allowing the use of DML (Data Manipulation Language) against the document. The XML DB repository represents XML content as documents in a folder hierarchy, and allows use of hierarchical metaphors, such as paths and URLs, for access to these documents. It should be noted that Oracle XML DB repository is an integrated part of the Oracle Database 10g.
XML documents can be stored in the database by simply inserting the XML document file using SQL, PL/SQL, Java, or through one of the three popular protocols FTP, HTTP, or WebDAV that Oracle XML DB has native support for. Getting XML data out of your database can be as simple as executing a SQL query or reading a file using one of those Internet-standard protocols. WebDAV stands for web-based distributed authoring and versioning. It is a set of extensions to the HTTP protocol that allows users to collaboratively edit and manage files on remote web servers. Figure 8-3 shows a listing of directories containing XML files. This type of index is familiar to many readers, except that Oracle XML DB displays this one.
NOTE
Windows Explorer can connect directly to the Oracle XML DB repository using one's own database login username and password. No additional Oracle- or Microsoft-specific software has to be installed in order to make this work. This means that end users can work with the Oracle XML DB repository using the tools and interfaces with which they are already familiar.
The introduction of XML Schema expanded the scope of XML from interchange to modeling and storage. XML Schema is another W3C standard that specifies the structure, content, and certain semantics for a set of XML documents. Its purpose is to define the legal building blocks of an XML document. An XML Schema includes the valid tag-sets, the constraints placed on XML elements, and the specifications for data types, derivation, and inheritance. The following code is a partial listing of an
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