126 The XML Files: Develo pment of XML/XSL Applications Using WebS phere Studio
</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 primar y 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. T he CLOB data type is itself derived from the
LOB (large object) data type.