	CS 683 Emerging Technologies Spring Semester, 2003 XML Namespaces and Schemas
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Contents of Doc 9, XML Namespaces and Schemas

References
Learning XML , Erik Ray, O'Reilly, 2001

Namespaces in XML, http://www.w3.org/TR/REC-xml-names/

XML Schema Part 0: A Primer, http://www.w3.org/TR/xmlschema-0/

XML Schema Part 1: Structures, http://www.w3.org/TR/xmlschema-1/

XML Schema Part 2: Datatypes, http://www.w3.org/TR/xmlschema-2/


Doc 9, XML Namespaces and Schemas Slide # 2

Namespaces

An XML namespace is a group of

Elements
Attributes

XML namespaces allows mixing of elements from different DTDs


Doc 9, XML Namespaces and Schemas Slide # 3

Namespace Tag name Format

   <namespacePrefix:tagName>

Example

   <sdsu:from>Roger</sdsu:from>
Doc 9, XML Namespaces and Schemas Slide # 4

Declaring a Namespace Format

   xmlns:namespaceName = ‘url’

The url

Is a unique identifier for the namespace

Sometimes points to the defining DTD

Sometimes just point to definers web site

Can point to nothing

Example

   <sdsu:from xmlns:sdsu=”http://www.sdsu.edu”>
      Roger</sdsu:from>


Doc 9, XML Namespaces and Schemas Slide # 5

Sample Use of Namespace

<?xml version="1.0" ?> 
<whitney:greetings  xmlns:whitney=”http://www.eli.sdsu”>
   <whitney:from>
         <whitney:firstname>Roger</whitney:firstName>
   </whitney:from>
   <whitney:to>
         <whitney:firstname>John</whitney:firstName>
   </whitney:to>
   <whitney:message>Hi</whitney:message>
</whitney:greetings>
Doc 9, XML Namespaces and Schemas Slide # 6

Using Multiple Namespaces

<?xml version="1.0" ?> 
<whitney:greetings  xmlns:whitney=”http://www.eli.sdsu”
         xmlns:godot=”http://www.waiting.com”>
   <whitney:from>
         <godot:firstname>Roger</godot:firstName>
   </whitney:from>
   <whitney:to>
         <godot:firstname>John</godot:firstName>
   </whitney:to>
   <whitney:message>Hi</whitney:message>
</whitney:greetings>

Limiting a namespace to part of document

<?xml version="1.0" ?> 
<whitney:greetings  xmlns:whitney=”http://www.eli.sdsu”
         >
   <godot:from xmlns:godot=”http://www.waiting.com”>
         <godot:firstname>Roger</godot:firstName>
   </godot:from>
   <whitney:to>
         <whitney:firstname>John</whitney:firstName>
   </whitney:to>
   <whitney:message>Hi</whitney:message>
</whitney:greetings>


Doc 9, XML Namespaces and Schemas Slide # 7

Default Namespace
All tags are in the ”http://www.eli.sdsu” namespace

<?xml version="1.0" ?> 
<greetings  xmlns=”http://www.eli.sdsu”>
   <from>
         <firstname>Roger</firstName>
   </from>
   <to>
         <firstname>John</firstName>
   </to>
   <message>Hi<message>
<greetings>


Doc 9, XML Namespaces and Schemas Slide # 8

Multiple and Default Namespace

<?xml version="1.0" ?> 
<greetings  xmlns=”http://www.eli.sdsu”
         xmlns:godot=”http://www.waiting.com”>
   <from>
         <godot:firstname>Roger</godot:firstName>
   </from>
   <to>
         <firstname>John</firstName>
   </to>
   <message>Hi</message>
</greetings>


Doc 9, XML Namespaces and Schemas Slide # 9

Schemas

Using a DTD to define an element

The content is a string
There is no way restrict the content

      <age>21</age>
      <age>The cat in the hat is Back</age>

Schemas are a way to define XML documents

Allow element content to have a type
Allow element content to be restricted


Doc 9, XML Namespaces and Schemas Slide # 10

Defining Schemas
Schemas are defined using XML

Don’t need DTDs for defining types

Plain XML parsers do not validate XML documents


Doc 9, XML Namespaces and Schemas Slide # 11

W3C Schema

Main W3C site on Schema

http://www.w3.org/XML/Schema

XML Schema Part 0: A Primer

http://www.w3.org/TR/xmlschema-0/

XML Schema Part 1: Structures

http://www.w3.org/TR/xmlschema-1/

XML Schema Part 2: Datatypes

http://www.w3.org/TR/xmlschema-2/


Doc 9, XML Namespaces and Schemas Slide # 12

Sample Schema

<xsd:schema 
         xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <xsd:element name="address" type="USAddress"/>
   <xsd:complexType name="USAddress">
      <xsd:sequence>
         <xsd:element name="name"   type="xsd:string"/>
         <xsd:element name="street" type="xsd:string"/>
         <xsd:element name="city"   type="xsd:string"/>
         <xsd:element name="state"  type="StateAbrreviation"/>
         <xsd:element name="zip"    type="xsd:decimal"/>
      </xsd:sequence>
   </xsd:complexType>
   <xsd:simpleType name="StateAbrreviation">
      <xsd:restriction base="xsd:string">
         <xsd:length value="2" />
      </xsd:restriction>
   </xsd:simpleType>
</xsd:schema>


Doc 9, XML Namespaces and Schemas Slide # 13

XML Using the Schema

<?xml version="1.0"?>
   <address>
      <name>Alice Smith</name>
         <street>123 Maple Street</street>
         <city>Mill Valley</city>
         <state>CA</state>
         <zip>90952</zip>
   </address>

Note the XML does not explicitly link to the schema defined on the last page. Future examples will show how to link to the schema


Doc 9, XML Namespaces and Schemas Slide # 14

Simple Types

Diagram is from http://www.w3.org/TR/xmlschema-2/


Doc 9, XML Namespaces and Schemas Slide # 15

Some Simple Schema Types

Simple Type	Examples (delimited by commas)
string	Confirm this is electric
normalizedString	Confirm this is electric
byte	-1, 126
unsignedByte	0, 126
base64Binary	GpM7
hexBinary	0FB7
integer	-126789, -1, 0, 1, 126789
positiveInteger	1, 126789
negativeInteger	-126789, -1
nonNegativeInteger	0, 1, 126789
nonPositiveInteger	-126789, -1, 0
int	-1, 126789675
unsignedInt	0, 1267896754
long	-1, 12678967543233
unsignedLong	0, 12678967543233
short	-1, 12678
unsignedShort	0, 12678
decimal	-1.23, 0, 123.4, 1000.00
float	-INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN
double	-INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN
boolean	true, false
time	13:20:00.000, 13:20:00.000-05:00
dateTime	1999-05-31T13:20:00.000-05:00
duration	P1Y2M3DT10H30M12.3S
date	1999-05-31
gMonth	--05--
gYear	1999
gYearMonth	1999-02
gDay	---31
gMonthDay	--05-31

Table from http://www.w3.org/TR/xmlschema-0/


Doc 9, XML Namespaces and Schemas Slide # 16

Some Simple Schema Types Continued

Name	shipTo
QName	po:USAddress
NCName	USAddress
anyURI	http://www.example.com/, http://www.example.com/doc.html#ID5
language	en-GB, en-US, fr


Doc 9, XML Namespaces and Schemas Slide # 17

Restricting Types

A base type can be restricted along facets

   <xsd:simpleType name="StateAbrreviation">
      <xsd:restriction base="xsd:string">
         <xsd:length value="2" />
      </xsd:restriction>
   </xsd:simpleType>


Doc 9, XML Namespaces and Schemas Slide # 18

String Facets

length


Exact length of the string

minLength
maxLength


Minimum (maximum) length of the string

pattern


Regular expression pattern defining legal values

enumeration


List of all possible legal values

whiteSpace


Rules for handling whitespace
preserve
replace (tab, line feed, carriage return with space)
collapse

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