CRITICAL SKILL 8.2 Oracle XML DB: Use XML in the Database

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NOTE
As you may have noticed, we have glossed over the discussion of XML—it is a very big topic demanding its own phone book–sized volume. We will attend to Oracle XML DB specifics in the rest of this chapter, and leave you to discover the big picture of XML on your own.

CRITICAL SKILL 8.2
Oracle XML DB: Use XML in the Database

XML is quickly being adopted as the data transport mechanism on the information highway—it is a W3C-endorsed standard markup language for documents. W3C stands for World Wide Web Consortium, an organization of approximately 400 members. They represent both public and private sectors, whose goal is to develop interoperable technologies (specifications, guidelines, software, and tools) for the World Wide Web. The following is an example XML document, leveraging the power of custom tags:

<?xml version=''1.0"?>
<book isbn="0078822424" >
  <publisher>"OsborneMcGraw-Hill"</publisher>
  <title>Oracle Data Warehousing: The Practical Guide to Building a Data Warehouse</title>
  <author>Michael Abbey</author>
  <author>Michael Corey</author>
  <book_image href="0078822424.gif"/>
  <print>paperback</print>
  <instock>yes</instock>
  <price>55.95</price>
</book>

The first line in the preceding code specifies that it is an XML document. The rest of the document is a text format whose hierarchical structure and metadata is specified by tags between brackets and its data enclosed within the tags. There are three primary uses of XML:

Exchanges information As stated earlier, XML is widely used as a mechanism for the transport of information, and is generated from a database, document, or from web content in a file system.

Offers a storage format XML's format meets the requirements for long-lived or structurally rigorous document-centric information. It is the introduction of XML Schema, another W3C standard that expanded the scope of XML from interchange to modeling and storage. The purpose of an XML Schema is to

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