xml overview

eXtensible Markup Language

Markup Language

SGML

WML

GML

..ML

Markup Language

� A Markup Language is a computer language that specifies the structure and content of a document by breaking the document down into the series of elements

XML

� XML stands for eXtensible Markup Language

� XML is a markup language much like HTML

� It’s a new markup language,developed by the W3C(www.w3.org),mainly to overcome limitations in HTML

� XML was designed to describe data

� XML tags are not predefined in XML.You must define your own tags

XML & HTML

� HTML and XML were designed with different goals

� HTML was designed to display data and to focus on how data looks

� XML was designed to describe data and to focus on what data is

� HTML is about displaying information, XML is about describing information

XML & HTML

� HTML tag : pre-defined tag<b>John</b>

� XML tag : user-defined tag<Name>John</Name>

HTML

<b>025447891</b>

Markup Language

XML

<myphonenumber>025447891</myphonenumber>

Markup Language Example

XML Example

<?xml version=“1.0”?><employee><id>001</id><name>Prapoj Sukmanont</name><city>Bangkok</city> <email>prapojs@hotmail.com</email>

</employee>

XML

xml01.xml

Element Structure

<tag> Content </tag>

Open Tag(start-tag) Close Tag(end-tag)

Element Name

XML Structure

<?xml version=“ 1.0” ?><root>

<child><sub_child></sub_child>

</child><child>

<sub_child></sub_child>

</child></root>

root

child child

sub_child sub_child

XML File Structure

Document Elements

Prolog

File name : *.xml

Prolog

� XML Declaration� <?xml version=“1.0”?>

� Document Type Declaration� <!DOCTYPE PurchaseOrder SYSTEM “po.dtd”>

� Processing Instruction(PI)� <?xml-stylesheet type=“ text/css” href=“ test.css”?>

Document Elements

<employee><id>001</id><name>Prasit Lee</name><city>Bangkok</city> <email>prasitl@hotmail.com</email>

</employee>

XML File Structure : Prolog

Document Elements

File name : *.xml

1. XML Declaration

2. Document Type Declaration (DTD)

3. Processing Instruction (PI)

Prolog

XML Example

<?xml version=“1.0” ?><employee>

<id>001</id><name>Prasit Lee</name><city>Bangkok</city> <email>prasitl@hotmail.com</email>

</employee>

xml01.xml

Thai Language XML Example

<?xml version=“1.0” encoding=“ windows-874” ?><employee>

<id>001</id><name>ประสิทธิ� ลี</name><city>กรุงเทพ</city>

<email>prasitl@hotmail.com</email></employee>

xml01th.xml

XML Benefits

Self-describe Data

Data Exchange

Messaging Format for Application

XML BenefitsXML Benefits

So on…(RSS, ebXML, XML Applications…)

CML, MathML, MusicML, VoiceML …

Text File & XML File

Text File

1,John,Bangkok2,David,New York3,Peter,London

XML File

<?xml version=“1.0” ?><employee><id>1</id><name>John</name><city>Bangkok</city> <id>2</id><name>David</name><city>New York</city> <id>3</id><name>Peter</name><city>London</city>

</employee>

employee.txt employee.xml

Data Exchange ExampleDB Server 1

XML File

<?xml version=“1.0” ?><employee><id>1</id><name>John</name><city>Bangkok</city> <id>2</id><name>David</name><city>New York</city> <id>3</id><name>Peter</name><city>London</city>

</employee>

employee.xml

Database

DB Server 2

Database

XML Parser XML Parser

XML Processor

� After the XML document is created, it needs to be evaluated by an application known as an XML processor or XML parser

� Part of the function of the parser is to interpret the document’s code and verify that it satisfies all of the XML specifications for document structure and syntax

� Microsoft developed an XML parser called MSXML (msxml.exe) for its Internet Explorer browser

Well-Formed XML

“A Well-Formed XML document contains no syntax

errors and satisfies the specifications for XML codes

as laid out by W3C”

1. Root Element

<?xml version=“1.0” ?><employee>

<id>001</id><name>Prapoj Sukmanont</name><city>Bangkok</city><email>prapojs@hotmail.com</email>

</employee>

Root Element

2. Element Naming

� XML elements must follow these naming rules

� Names can contain letters,numbers, and other characters.Names must not start with a number or other punctuation characters

� Names must not start with the letter xml(or XML or Xml ...)

� Names cannot contain space,(*,? And +)

� Avoid “ -” and “ .” in names

� The “ :” should not be used in element names

Element Naming : Example

<Company><_Company><My_company><First-name><Last.name>

<-Company><9Company><.My_company><Name*><Name?><Name+><xmlbook><first name>

OKNot OK

3. Closed Tag

<?xml version=“1.0” ?><employee><id>001</id><name>Prapoj Sukmanont</name><city>Bangkok</city> <email>prapojs@hotmail.com</email></employee>

4. Proper Nesting Tag

<ID><name>

</ID></name>

<ID><name>

</name></ID>

5. Case-sensitive

<ID><name>

</Name></ID>

<ID><name>

</name></ID>

6. Attribute Value

<employee id=001><name>

</name></employee>

<employee id=“001”><name>

</name></employee>

<employee id=‘001’><name>

</name></employee>

Element Attribute

� An attribute describes a feature or characteristic of an element .Attributes

are often used to provide additional information about an element .The

syntax for adding an attribute to an element is

� Attribute name constraints:

� The name must begin with a letter or underscore (_)

� Space are not allowed in attribute names

� Attribute names should not begin with the text string “xml”

<element_name attribute_name=“Attribute value”> … </element_name>

Well-Formed XML Example

<?xml version=“1.0” ?><employee><id>001</id><name prefix=“Mr”>Prapoj Sukmanont</name><city>Bangkok</city> <email>prapojs@hotmail.com</email>

</employee>

Well-FormedXML

xml02.xml

� Normal element

� <Name>Prasit Lee </Name>

� Empty element

� <telephone></telephone>

� <telephone/>

XML Element Types

Element Content

� Nested element

� Character data

� Reference Entity

� CDATA

� Comment

Element Content

<Start-tag> Content </End-tag>

1. Nested Element

…<BOOK>

<TITLE> XML Book </TITLE><AUTHOR>Prasit Lee </AUTHOR>

</BOOK>

2. Character Data

…<TITLE> XML Book </TITLE><AUTHOR>Prasit Lee </AUTHOR>…

3. Entity Reference

& &amp;< &lt;> &gt;“ &quot;‘ &apos;

XML Example

<?xml version=“1.0” ?><Example>

<Statement>if x < y </Statement></Example>

xmlerror1.xml

Not XML Well-formed

XML Example

<?xml version=“1.0” ?><Example>

<Statement>if x &lt; y </Statement></Example>

xml03.xml

4. CDATA Section

<?xml version=“1.0”?><Example>

<Statement><![CDATA[

if x > y and a < b]]>

</Statement></Example>

xml04.xml

CDATA

� Sometimes, an XML document needs to store large blocks of text containing the < and > symbols. In that case, it would be cumbersome to replace all of the < and > symbols with &lt; and &gt; character reference, the code itself will be difficult to read

� Instead of using character references, you can place large blocks of text into a CDATA section

� A CDATA section is a large block text that the XML processor interprets only a text

<![CDATA[Text block

]]>

5. Comment

…<BOOK>

<!-- This is comment create by “Prasit” 03.02.2012--><TITLE> XML Book </TITLE><AUTHOR>Prasit Lee </AUTHOR>

</BOOK>