The document provides an overview of XML schemas, which are used to define and validate the structure of XML documents. Some key points: - XML schemas allow defining data types and content models for XML elements and attributes. They provide better features than DTDs for describing documents. - An XML schema is defined in its own XML document with the .xsd file extension. It can then be referenced by XML documents to validate their structure. - The root <schema> element defines the schema. It contains definitions of elements, attributes, data types etc. Namespaces are used to identify element types. - Benefits of schemas over DTDs include support for namespaces, built-in and custom data types, and

1. ‫أكاديمية الحكومة اإللكترونية الفلسطينية‬
The Palestinian eGovernment Academy
www.egovacademy.ps
Tutorial II: Data Integration and Open Information Systems
Session3
XML Schemas
Dr. Ismail M. Romi
Palestine Polytechnic University
PalGov © 2011 1

2. About
This tutorial is part of the PalGov project, funded by the TEMPUS IV program of the
Commission of the European Communities, grant agreement 511159-TEMPUS-1-
2010-1-PS-TEMPUS-JPHES. The project website: www.egovacademy.ps
Project Consortium:
Birzeit University, Palestine
University of Trento, Italy
(Coordinator )
Palestine Polytechnic University, Palestine Vrije Universiteit Brussel, Belgium
Palestine Technical University, Palestine
Université de Savoie, France
Ministry of Telecom and IT, Palestine
University of Namur, Belgium
Ministry of Interior, Palestine
TrueTrust, UK
Ministry of Local Government, Palestine
Coordinator:
Dr. Mustafa Jarrar
Birzeit University, P.O.Box 14- Birzeit, Palestine
Telfax:+972 2 2982935 mjarrar@birzeit.eduPalGov © 2011
2

3. © Copyright Notes
Everyone is encouraged to use this material, or part of it, but should
properly cite the project (logo and website), and the author of that part.
No part of this tutorial may be reproduced or modified in any form or by
any means, without prior written permission from the project, who have
the full copyrights on the material.
Attribution-NonCommercial-ShareAlike
CC-BY-NC-SA
This license lets others remix, tweak, and build upon your work non-
commercially, as long as they credit you and license their new creations
under the identical terms.
PalGov © 2011 3

4. Tutorial Map
Topic h
Intended Learning Objectives
Session 1: XML Basics and Namespaces 3
A: Knowledge and Understanding
Session 2: XML DTD’s 3
2a1: Describe tree and graph data models.
Session 3: XML Schemas 3
2a2: Understand the notation of XML, RDF, RDFS, and OWL.
Session 4: Lab-XML Schemas 3
2a3: Demonstrate knowledge about querying techniques for data
models as SPARQL and XPath. Session 5: RDF and RDFs 3
2a4: Explain the concepts of identity management and Linked data. Session 6: Lab-RDF and RDFs 3
2a5: Demonstrate knowledge about Integration &fusion of Session 7: OWL (Ontology Web Language) 3
heterogeneous data. Session 8: Lab-OWL 3
B: Intellectual Skills Session 9: Lab-RDF Stores -Challenges and Solutions 3
2b1: Represent data using tree and graph data models (XML & Session 10: Lab-SPARQL 3
RDF). Session 11: Lab-Oracle Semantic Technology 3
2b2: Describe data semantics using RDFS and OWL. Session 12_1: The problem of Data Integration 1.5
2b3: Manage and query data represented in RDF, XML, OWL. Session 12_2: Architectural Solutions for the Integration Issues 1.5
2b4: Integrate and fuse heterogeneous data. Session 13_1: Data Schema Integration 1
C: Professional and Practical Skills Session 13_2: GAV and LAV Integration 1
2c1: Using Oracle Semantic Technology and/or Virtuoso to store Session 13_3: Data Integration and Fusion using RDF 1
and query RDF stores. Session 14: Lab-Data Integration and Fusion using RDF 3
D: General and Transferable Skills
2d1: Working with team. Session 15_1: Data Web and Linked Data 1.5
2d2: Presenting and defending ideas. Session 15_2: RDFa 1.5
2d3: Use of creativity and innovation in problem solving.
2d4: Develop communication skills and logical reasoning abilities. Session 16: Lab-RDFa 3
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5. Session ILO’s:
After completing this session students will be able to:
•Manage data represented in XML.
•Represent data using tree and graph data models.
•Build Well-Formed XML Document.
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6. Session4: XML Schemas
Session Overview:
<Benefits of XML Schemas />
<How to create and use XML Schemas/>
<How to document your XML Schemas/>
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7. XML Schema
• The term XML Schema is used to refer to the specific
W3C XML Schema technology.
• W3C XML Schemas, much like DTDs, enable you to
describe the structure of an XML document.
• XML Schema definitions are also commonly referred
to as XSDs.
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8. Benefits of XML Schemas
 XML Schemas are created using basic XML, while DTDs
utilize a separate syntax.
 XML Schemas fully support the Namespace
Recommendation.
 XML Schemas enable you to validate text element content
based on built-in and user-defined data types.
 XML Schemas enable you to more easily create complex
and reusable content models.
 XML Schemas enable the modeling of programming
concepts such as object inheritance and type substitution.
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9. Do We Still Need DTDs?
• XML Schemas provide better features for describing
documents—as well as a more common syntax—they
provide no ENTITY functionality.
• In many XML documents and applications, the ENTITY
declaration is important.
• DTD can be embedded in the xml document.
• DTD supported by the SGML.
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10. XML Schemas
XML Schema divided into three parts:
 An introduction to XML Schema concepts at:
www.w3.org/TR/xmlschema-0/
 A document that defines all of the structures used in XML
Schemas at: ww.w3.org/TR/xmlschema-1/
 A document that describes XML Schema data types at
www.w3.org/TR/xmlschema-2/
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11. The XML Schema Document
• Most XML Schemas are stored within a separate XML
document.
• XML Schemas function very similarly to external DTDs
• XML document contains a reference to the XML Schema
that defines its vocabulary.
• An XML document that adheres to a particular XML
Schema vocabulary is called an XML Schema instance
document.
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12. XSD Example
<?xml version=‖1.0‖?>
<schema xmlns=‖http://www.w3.org/2001/XMLSchema‖
xmlns:target=‖http://www.example.com/name‖
targetNamespace=‖http://www.example.com/name‖
elementFormDefault=‖qualified‖>
<element name=‖name‖>
<complexType>
<sequence>
<element name=‖first‖ type=‖string‖/>
<element name=‖middle‖ type=‖string‖/>
<element name=‖last‖ type=‖string‖/>
</sequence>
<attribute name=‖title‖ type=‖string‖/>
</complexType>
</element>
</schema>
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13. The <schema> Element
The <schema> element is the root element of every XML
Schema:
<?xml version="1.0"?>
<xs:schema>
...
...
</xs:schema>
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14. The <schema> Element….Cont
 The <schema> element may contain some attributes.
 A schema declaration often looks something like this:
<?xml version="1.0"?>
<xs:schema
xmlns:xs= “http://www.w3.org/2001/XMLSchema”
targetNamespace= “http://www.w3schools.com”
xmlns= “http://www.w3schools.com”
elementFormDefault= "qualified">
...
...
</xs:schema>
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15. The XML schema Namespace
• You can use any of the following <schema>:
<schema
xmlns=”http://www.w3.org/2001/XMLSchema”>
<xs:schema
xmlns:xs=”http://www.w3.org/2001/XMLSchema”>
<xsd:schema
xmlns:xsd=”http://www.w3.org/2001/XMLSchema”>
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16. • Indicates that the elements and data types
used in the schema come from the
―http://www.w3.org/2001/XMLSchema" namespace.
• It also specifies that the elements and data
types that come from the
―http://www.w3.org/2001/XMLSchema" namespace
should be prefixed with xs: or xsd:
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17. Target Namespaces
• The primary purpose of XML Schemas is to declare
vocabularies.
• These vocabularies can be identified by a namespace that
is specified in the target namespace attribute.
• When declaring a target namespace, it is important to
include a matching namespace declaration.
<xs:schema xmlns:xs=‖http://www.w3.org/2001/XMLSchema‖
targetNamespace=‖http://www.example.com/name‖
xmlns=‖http://www.example.com/name‖>
Indicates the Indicates that the
elements defined by this
default namespace.
schema come from this
target namespace.
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18. Element and Attribute Qualification
<schema xmlns=‖http://www.w3.org/2001/XMLSchema‖
xmlns:target=‖http://www.example.com/name‖
targetNamespace=‖http://www.example.com/name‖
elementFormDefault=‖qualified‖>
elementFromDefault = ―qualified‖ or ―unqualified‖
attributeFromDefault ― qualified‖ or ―unqualified‖
• qualified: if it has an associated namespace.
• unqualified: if it hasn’t associated namespaces
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19. Simple <element> Declarations
<xs:element name="xxx"
type="yyy"/>
 xxx: the name of the element
• The name must follow the rules for XML names.
 yyy: the data type of the element.
 XML Schema has a lot of built-in data types.
 The most common types are:
– xs:string
– xs:decimal
– xs:integer
– xs:boolean
– xs:date
– xs:time
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20. Example
• Here are some simple XML elements:
<lastname>Jones</lastname>
<age>36</age>
<dateborn>1970-03-27</dateborn>
• Here are the corresponding simple element
definitions:
<xs:element name="lastname" type="xs:string"/>
<xs:element name="age" type="xs:integer"/>
<xs:element name="dateborn" type="xs:date"/>
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21. Cardinality
• Cardinality represents the number of
occurrences of a specific element within a
content model.
<element name=‖first‖ type=‖string‖ minOccurs=‖x‖ maxOccurs=‖y‖/>
• x : minimum number of occurrence, default =1
• y : maximum number of occurrence, unbound: open occurrence
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22. Default and Fixed Values
 Simple elements may have a default value OR a fixed
value specified.
 Default value is automatically assigned to the element
when no other value is specified.
 In the following example the default value is "red":
<xs:element name="color" type="xs:string" default="red"/>
 Fixed value is also automatically assigned to the element,
and you cannot specify another value. In the following
example the fixed value is "red":
<xs:element name="color" type="xs:string" fixed="red"/>
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23. <complexType> Declarations
A complex element is an XML element that
contains other elements and/or attributes.
There are four kinds of complex elements:
empty elements
elements that contain only other elements
elements that contain only text
elements that contain both other elements and
text
Note: Each of these elements may contain
attributes as well!
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24. empty elements
• A complex XML element, "product", which is
empty:
<product pid="1345"/>
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25. elements that contain only other elements
• A complex XML element, "employee", which
contains only other elements:
<employee>
<firstname>John</firstname>
<lastname>Smith</lastname>
</employee>
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26. elements that contain only text
• A complex XML element, "food", which
contains only text:
<food type="dessert“ Ice cream</food>
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27. elements that contain both other elements and text
• A complex XML element, "description",
which contains both elements and text:
<description> It happened on
<date lang="norwegian">03.03.99</date> ....
</description>
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28. How to Define a Complex Element
• Look at this complex XML element,
"employee", which contains only other
elements:
<employee>
<firstname>John</firstname>
<lastname>Smith</lastname>
</employee>
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29. The "employee" element can be declared directly by naming the element,
like this:
<xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname“ type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
• If you use the method described above, only the "employee" element
can use the specified complex type.
• Note that the child elements, "firstname" and "lastname", are
surrounded by the <sequence> indicator. This means that the child
elements must appear in the same order as they are declared.
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30. <attribute> Declarations
• The syntax for defining an attribute is:
<xs:attribute name="xxx" type="yyy"/>
– Where xxx is the name of the attribute and yyy specifies
the data type of the attribute.
– Simple elements can’t have attributes
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31. Summary
• XML Schema is used to refer to the specific W3C
XML Schema technology.
• W3C XML Schemas, much like DTDs, enable you
to describe the structure of an XML document.
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32. Refrences
• Hunter, H, Rafter, J., Fawcett, J., Vlist, E., Ayers, D., Duckett, J., Watt,
A., McKinnon,L., (2007), "Beginning XML", 4th Ed.,Wiley Publishing
Inc: Indiana, USA.
• Ray, E., (2003), "Learning XML", 2nd Ed., O’Rreilly Media Inc.: USA.
• Amiano, M., D'Cruz, C., Ethier, K., Thomas, M., (2006), XML:
Problem - Design – Solution", Wiley Publishing Inc: Indiana, USA.
• http://www.w3.org
• http://www.w3schools.com
• http://www.xml.com
• http://www.xml.org
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33. <e-Gov> Thank you </e-Gov>
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