Organization

• No tutorial next week

• Next sheet hand in on the 05.06.07 Tuesday

<?xml version="1.0"?><movies xmlns:xmllib="http://www.xmlmovielibrary.com">

<xmllib:title>Star Wars:Episode I-The Phantom Menace</xmllib:title><xmllib:year>1999</xmllib:year><purchase xmlns:xmllib="http://www.othermovielibrary.com">

<xmllib:title>Star Wars:Episode II-Attack of the Clones </xmllib:title><xmllib:year>2002</xmllib:year>

</purchase><xmllib:title>Star Wars:Episode III-Revenge of the Sith</xmllib:title><xmllib:year>2005</xmllib:year>

</movies>

The W3C Namespaces in XML Recommendation enforces some namespace constraints:

• Prefixes beginning with the three-letter sequence x, m, and l, in any case combination, are reserved for use by XML and XML-related specifications. Although not a fatal error, it is inadvisable to bind such prefixes. The prefix xml is by definition bound to the namespace name http://www.w3.org/XML/1998/namespace.

• A prefix cannot be used unless it is declared and bound to a namespace. (Using variable in Java without declaring it)

<?xml version="1.0"?><bk:book xmlns:bk="tar">

<bk:title/></bk:book>

<?xml version="1.0"?><bk:book xmlns:bk="tar">

<title/></bk:book>

<?xml version="1.0"?><book xmlns="tar">

<title xmlns=“”/></book>

<?xml version="1.0" encoding="UTF-8"?><schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:abc="http://abc.com/" targetNamespace="http://abc.com/" elementFormDefault="unqualified" attributeFormDefault="unqualified">

<element name="books" type="abc:t1"/>

<element name="comments" type="string"/>

<complexType name="t1"><sequence>

<element name="book" type="abc:t2"/><element ref="abc:comments" minOccurs="0"/>

</sequence></complexType>

<complexType name="t2"><sequence>

<element name="title" type="string"/></sequence>

</complexType></schema>

<?xml version="1.0" encoding="UTF-8"?><bk:books xmlns:bk="http://www.abc.com/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<book><title>XML for dummies</title>

</book><bk:comments>Books one the topc XML</bk:comments>

</bk:books>

Qualified:definine elements and attributes in the target namespace Unqualified: elements and attributes in any namespace

<?xml version="1.0" encoding="UTF-8"?><bk:books xmlns:bk="http://www.abc.com/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<bk:book><bk:title>XML for dummies</bk:title>

</bk:book><bk:comments>Books one the topc XML</bk:comments>

</bk:books>

…<xsd:key name="itemNumKey"> <xsd:selector xpath=".//item"/> <xsd:field xpath="number"/> </xsd:key><xsd:keyref name="itemNumKeyRef" refer="itemNumKey"> <xsd:selector xpath="products/*"/> <xsd:field xpath="@number"/> </xsd:keyref></xsd:element>…..

Unique vs. Key

• Unique = guarantees uniqueness, nullable• Key = guarantees uniqueness and

existence– always be present (minOccurs must be

greater than zero)– be non-nullable (i.e., nullable="false")– be unique

• Key implies unique, but unique does not imply key