</restriction>

</simpleType>

</element>

<element name="ARRIVAL" nillable="true"> <simpleType>

<restriction base="string"> <maxLength value="10"/>

</restriction>

</simpleType>

</element>

</schema>

The main difference here is that the primary key is now generated as an attribute and a sequence has been forced on the remaining columns and they can be set to null.

6.4 DB2 XML Extender

This section has been adapted from Chapter 9 of the redbook DB2 e-business Guide (SG2-6539).

There are different DB2 Extender products available to provide the functions to support e-Business requirements that include support for different media types, full text search capability, fast search capability to be used over the Internet, and support for XML data. These are:

￿XML Extender

￿Text Extender

￿Net Search Extender

￿Audio Image Video (AIV) Extender

The basic idea behind all the DB2 extenders is that they provide the means to support a new data type. That is, a table column can hold special type of data, such as a text document. In order to support the new data type, the extenders define user defined types, user defined functions, stored procedures, and a new set of tables. The Extenders also exploit DB2's support for large objects of up to 2 gigabytes, and use DB2 triggers to provide integrity checking across database tables ensuring the referential integrity of the data.

A User-Defined Type (UDT) is a way to create a new data type that has its own semantics based on existing built-in types. For example, the XML Extender creates the XMLCLOB UDT from the existing CLOB (character large object) data type to support XML data in DB2. The CLOB data type is itself derived from the LOB (large object) data type.

126 The XML Files: Development of XML/XSL Applications Using WebSphere Studio

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IBM Version 5 manual DB2 XML Extender