xml, mgu btech cse

What are Markups

A text book publishing professional takes basic text

from authors on paper and write markup instructions

to tell the type setter how to make the document look

on the printed page. eg: ”insert a paragraph break

here, make this word bold ,double space this text

”,etc.

<Chapter starting><Heading “Java”><Sub heading introduction to java><begin paragraph>Java language uses interpreter----------<end paragraph><begin paragraph>----------------------------------------------------------------<end paragraph><Sub heading><begin paragraph>--------------------------------------------------------------------<end paragraph>--<Chapter end>

What are Markups (contd.)

Standard Generalized Markup Language (SGML)

• In 1986 an international standard for markup languages came into existence

called Standard Generalized Markup Language • XML is a subset of SGML intended to make SGML light enough for use on

the web • XML is a proper subset of SGML

XMLSGML

Standard Generalized Markup Language (SGML) (contd.)

Name Industry

ATA Aviation (Air Transport Authority)

Doc Book Technical Manual

Text Encoding Initiative (TEI) Encoding of literature

J2008 Automotive maintenance

Edgar Financial report of public companies

HTML Hyper Text Markup language

Pinnacles (PCIS) Semiconductor data

Some SGML initiatives

What is XML?

• XML is a framework used to create Markup Languages to describe

data in a structured manner, and an open technology for

electronic data exchange and storage.

eXtensible Markup Language (XML)

• The World Wide Web Consortium (W3C) XML Working Group derived

XML from SGML in 1996

• XML is an Extensible Markup Language because it is extensible according

to the user needs as the user can structure the data and add his own tags

• XML is actually a framework used to create other markup languages to

describe data in a structured manner

• XML documents contain only data and not formatting instructions

The relationship between SGML, XML and HTML

Text Encoding Initiative

HTML

Edgar

DocBookSGML

Channel Definition Format (CDF)

Open Financial Exchange (OFX)

Chemical Markup Language (CML)

Application languages Frameworks

XML

<h1> Personal Computers for sale </h1>

<h2> Maker: IBM PC </h2>

<h3> Model: Pentium IV </h3>

<table border =1>

<tr> <td> Storage </td></tr>

<tr> <td> RAM </td> <td>512 MB</td> </tr>

<tr><td> Hard Disk</td> <td>120 GB </td> </tr>

</table>

A Simple HTML

<PcForSale>

<Heading>Personal Computers for sale</Heading>

<Maker>IBM PC </Maker>

<Model> Pentium IV </Model>

<Storage>

<Ram Units ="MB">512</Ram>

<HardDisk Units ="GB">120</HardDisk>

</Storage>

</PcForSale>

The corresponding XML

Drawback of HTML

• A lot of useful information is lost when data is represented using HTML

• HTML has a fixed tag set, like <h1> , <table> , <tr> etc.

• HTML is an example of a markup language

Advantages of XML

• XML preserves useful information

• XML liberates information from the shackles of a fixed tag set

• XML provides a standardized frame work with which one can make his

own tags or use those defined by others that best fit the needs

• XML is a flexible framework in which you can create your own customized

markup language

• XML is a frame work for making markup languages

Electronic Documents

• Electronic documents consists of 3 distinct components.

• Data content - the words itself

• Structure - the document type and organization of its elements

• Presentation - the way the information is presented to the reader

• The significant benefits of XML is that the three aspects of a

document

are kept separate and made explicit in a computer system.

Presentation

Content

Structure

Traditional WYSIWYG Document

Presentation

Content

Structure

XML Document

Comparison between WYSIWYG and XML documents

Checking the structure of an XML document

• XML includes a mechanism for defining rules that control how documents

are structured and these rules are called Document type

Definitions (DTD)

• In Document Type Definitions by listing the elements types to be used and

indicating the structural order they can occur the structure of a XML

document can be checked

• A utility program called an XML parser is used to test whether or not the

document meets the prescribed rules

XMLDocument

Valid XML

XML RulesChecker (Parser)Structure

Rules (DTD) Invalid XML

Checking the structure of an XML document (contd.)

XML Style Language (XSL)

• XSL is used with XML to make XML look nicer in a browser

• XSL is similar to Cascaded Style Sheet used with HTML

• The use of XSL is to capture details about how the various elements in a

document should look and then to store them in a separate document

• Separating the content from the presentation allows the presentation to be

changed by simply changing the style sheet

• XSL is a simplified subset of the International Standard Style Language

known as DSSSL (ISO/IEC).

SGML

ISO 8879

DSSSL

ISO/IEC 10179 + CSS

XML

XSL

The relationship between XML, XSL and ISO Standards

eXtensible Link Language (XLL)

• In HTML <A> element is used for hypertext-linking

• The element is built directly into the language

• XLL standard is used with XML for hypertext-linking

SGML

ISO 8879

DSSSL

ISO/IEC 10179 + CSS

XML

XSL

Adding XLL to the family of XML standards

XLL

HyTime

ISO/IEC 10744 + TEI

Applications of XML

The world wide web and E-commerce cannot survive with out XML

There are a lot of examples where XML is used

1. Online Banking – Open financial Exchange Initiative.

2. Data base Integration.

Online Banking

• With the advent of the web the need for an inter change data representation

for financial data become necessary

• Users want to be able to purchase goods from anywhere on the web with

funds drawn from institutions anywhere in the world

• Users are least concern about the way the financial transactions are

represented

• The solution is a web-friendly internationally agreed standard notation for

expressing financial transactions

Online Banking (contd.)

•The hierarchical structure of the information found in financial transactions

is easily represented using the structured document philosophy of XML

<Statement Request>

<Bank Account>

<BankID>123456<BankID>

<AccountID>9999<AccountID>

<AccountType>CHEKING </AccountType>

<PersonName>Tom Hanks</PersonName>

</Bank Account>

</Statement Request>

This example conform to the Open Financial Exchange (OFX) specifications

Online Banking (contd.)

The transaction from a customer to a bank, requesting the establishment of a

recurring payment with 12 monthly installments<Recurrence> <Number>12</Number> <Frequency> MONTHLY </Frequency> <Payment Info> <From Bank> <Bank Id> 555432180 </Bank Id> <Account Id> 763984 </Account Id> <Account type> CHEKING </Account type> </From Bank> <Amount> 395.00. </Amount> <Payee ID> 77810. </Payee ID> <Pay Account >444-78-97572</Pay Account > <Date Due> 19971115 </Date Due> <Memo> Auto loan payment </Memo> </Payment Info></Recurrence>

Client Software

(eg. Microsoft Money)

OFX Documents

The Web OFX Documents

Financial Institution’s Software

OFX Conversion

Web Server

OFX interchange between financial institutions

Database Integration

• A lot of information in the world is stored in data bases like personal files,

health records, football results, stock prices etc

• The data base needs to be constantly updated and often change rapidly

• A mechanism is needed to access and modify the database using a web

interface

• The solution is to capture the database related information such as tables

fields, values etc. from the form and translate the data into XML format

and transfer it to the database

Name

Phone Number

Address

Submit

Data entry screen for a database

Data entry screen for a database

Web Browser

Web Server

Relational Database

Web Page Request

Web Page

XML tagged Data

XML tagged Data

<Phone book>

<Name> James Thomas </Name>

<Phone Number>27598191 </phone Number>

<Address> 20 MG Road Bangalore 560001 </Address>

</Phone book>

XML format of data sent to the Database for entry

The Commercial benefits of XML

• By using XML there are a number of benefits like

• The content of an XML page can be manipulated and rearranged and even

calculated to generate extra content at the client end with help of

scripting languages like Java

• The same content can be made to look completely different for different

users or different uses

• The content can be intelligently searched with the browser based on what it

contains

The Commercial benefits of XML (contd.)

• It is very difficult to move a document from one software package to another

• Document conversion from one format to another has become difficult due to

• The volume of document produced is increasing day by day

• The demands had changed these days from paper print out to other

requirements like online help files, Web pages, multilingual version,

speech synthesis etc

• The traditional documents are hard to reuse because of the tight coupling

between presentation and contents found in most documents

The Commercial benefits of XML (contd.)

• High quality formatting can be added automatically by specifying what the

document contains

• For XML different types of formatting can be applied to the same content in

order to achieve different results

• By using XML the content is freed from the shackles of any one particular

formatting system

• An XML document can meta amorphous to many different shapes and sizes

• The structure and the content are retained independently thus allowing the

document to be reformatted over and over again to a number of formats

XML Document

XML Web Browser

HTML

Online Help

Paper

Braille

Formatter

Formatter

Formatter

Formatter

Creating multiple formatted outputs from a XML document

XML Document XML DocumentHarvested XML Document

An XML document created from the component parts of other documents

Document Creation

• When a document is created it should be specified what the document is,

what components they contain and how the components are structured

• When the computer is told what is in the document then it can differentiate

between letters, invoices, copyright notices etc.

• By using XML the computer can be told what is in a document

• Name the component parts based on what they are

<Copyright>

<Para>This document is copyright….</Para>

</Copyright>

Benefits of XML

• XML documents are self describing

• When documents contain rich structural information complex queries can

be

precisely answered and searches gets good results

• In industry information interchange is very necessary for the existence

• It will be very difficult for information interchange with out a commonly

accepted standard

• By using an industry standard interchange notation the number of

converters can be minimized

Format A Format B

Format C Format D

Data exchange where there is no standard format for interchange

Format A Format B

Format C Format D

XML Interchange Format

Data exchange using standard format for interchange

Benefits of XML in brief

• The content of an XML page can be manipulated and rearranged and

even

calculated to generate extra content

• The same content can be made to look completely different for different

users or different uses

• XML is a completely open standard that safeguards the ownership of data

• XML documents describe themselves making searching, indexing and

locating information easier

• XML allows a high degree of automation in the labor intensive areas

Two views of an XML document

• An XML document can be looked at in two very distinct ways

• Logical structure

• Physical Structure

• In a logical structure an XML document is a hierarchy of information

• The character data of the document hangs in individual chunks out of a tree

like structure created by markups

Two views of an XML document (contd.)

• In a physical structure a single logical XML documents can be made up of a

number of distinct physical files known in XML as entities

• The full document is rooted in the entity known as the document entity

• Like the logical structure, the physical structure of an XML document is

hierarchical in nature

• An entity can contain references to other entities which themselves can

contain references to other entities

Logical View

IBMPC

Item type = “PC”

make specification blurb

brandsupplier id = “Compusa”

CPUType = “Pentium IV”

Speed units = “3 GH3”

Hard disktype =”IDE”size =””120”units = “GB”

IBM inspire A versatile PC…

Physical View

IBM PC

Entity A

( part1.xml )

Entity B

( part2.xml )

Entity A1

( part11.xml )

Entity A2

( part12.xml )

Two classes of XML document

• A well formed XML document is one from which as XML Processor can

successfully build a tree structure

• An XML Processor can successfully build a tree without a DTD

• Well-formed XML documents can be further classified as valid if they meet

the constrains spelled out in an associated DTD

• If an XML document is valid it is also well formed

• The set of all valid XML documents is a subset of the set of all well formed

XML documents

Two classes of XML document

Valid XML Documents

Well Formed

XML Documents

Two classes of XML processors

• An XML processor capable of checking for validity is known as a validating

XML processor

• The msxml processors from Microsoft is an example of a validating XML

processor

• An XML processor that ignores any validity constraints spelled out in DTD

is known as a nonvalidating XML processor

• Elfred is an example of nonvalidating XML processor

• Any processor capable of checking for validity is capable of checking for

well-formedness

Two classes of XML processors

Validating XML Processors

Nonvalidating XML Processors

How to create XML Documents

• Seven forms of markup can occur in XML documents and they are

1. Start and End tags

2. Attribute assignments

3. Entity references

4. Comments

5. Processing instructions

6. CDATA sections

7. Document Type Declarations

Start and End tags

• The presence of elements in an XML document is denoted by tags of various

forms

• The elements have start and end points denoted by start and end tags

• Elements can be nested to an arbitrary depth to describe very rich

information structures.

Some examples of Start tag and End tag

Tag Meaning

<greeting> Start a greeting element

</introduction> End an introduction element

<John Mathew> Bad start tag no space allowed in the element type name

<42> Bad start tag element type names cannot start with a number

</ product> Bad end tag no space allowed between the slash and the element type name

Start and End tags (contd.)

• Elements can be nested to any arbitrary depth using start and end tags

• By nesting elements to depth very rich information structures can be

described

• An empty element can be represented by a backslash before the closing “>” of

start tag

eg:- <introduction/>

Start and End tags (contd.)

<TypesOfCar> <Saloon> <Normal> <automatic> <Car> Model A </Car> </automatic> <manual> <Car> Model B </Car> </manual> </Normal> <FourWeelDrive> <automatic> <Car> Model C </Car> </automatic> </FourWeelDrive> </Saloon></TypeOfCar>

Attribute Assignments

• Attributes are pieces of information that are associated with XML elements

• In HTML we have the align attribute of the p element, the border attribute

of the table element

• Attribute come in verity of shapes and sizes that are controlled by DTD

• Attribute assignments always appear within the start-tag of an element

• The normal syntax of an attribute is

Element[name of attribute] ”=” [value of attribute]

eg. <Car colour=”Red”> , <Table border=2> ,

<animal legs=”4” blood=”cold”>

Entity references

• Entities are the physical building blocks of the XML documents

• An entity is a unit of text as single as character or as complex as an entire

document

• Consider the following piece of XML document

<Document>

If a<b and b< c then a<c

</Document>

Entity references (contd.)

• When the XML Parser parses the document it will complain when it sees

the

second “b” character because at that point it was expecting an equal

sign to start the value for the and attribute of the b element

• XML has a number of predefined entities

• In an XML document prepend an “&” and append a”;” to the name of the

entity so the above example can be rewritten as

<Document>

If a & lt; b and b< c then a & lt; c

</Document>


Entity Reference Interpretation

< <

> >

& &

' ‘

" “

Five built-in Entities in XML


• Entity references can be used to include entire files of XML text within the

text of other files

<Book>

&Chapter 1;

&Chapter 2;

&Chapter 3;

</Book>

• The three chapters of a book stored in separate entities to be gathered in to a

single Book element


• Shorthand notation are used in XML.

<!ENTITY dbms “Data Base Management System”>

• When dbms is referred the XML parser will insert the replacement text

“Data Base Management System”

eg. <ulysses> &dbms; is managed by Administrator

will be expanded as

Data Base Management System is managed by Administrator

Comments

• XML comments take exactly the same form as HTML comments.



• The string “--“ cannot be used within a comment.

Processing Instructions

• Processing Instruction is used to store application specific information in an

XML document

• The processing instructions pass straight through as SGML parser because

they are for the consumption of an application

eg1. <?rtf\page?> is a processing instruction to force a particular type setting

device to output a page break at particular place

eg2. <?XML version =”1.0” ?>

• This shows the version of XML and is a standard for all XML documents

CDATA sections

• In some cases a document may contain large numbers of characters that are

specially considered by an XML parser like < and >

• XML allows a block of text to be insulated from attention of the parser using

a CDATA section

<Document>

<![CDATA[ If a<b and b<c and a<c ]] >

</Document>

• By prefixing the string <![CDATA [ and appending the string ]]> the entire

section in insulated and passes through the parser with out any

problem

Document Type Declaration (DTD)

• The Document Type Definitions lists the elements types to be used in an

XML document and indicates the structural order they occur

• A DTD is to be associated with an XML document, the association is

achieved using the following declaration

<!DOCTYPE first SYSTEM “first.dtd”>

•It says the DTD for the document first is available in the file first.dtd

Creating XML DTD’s

Creating a DTD contain the following steps

• Element Type Declaration

• Attribute List Declarations

1) Attribute Types

2) Attribute Defaults

• Entity Declarations

Element Type Declarations

• To validate an XML document the validating XML parser needs to know

three principle things about each element

• What the element type is named

• What elements of that type can contain

• What attribute an element of that type has associated with it

• The element type name and its content model are declared together in an

element type declaration

1) <!ELEMENT contact (name, address, telephone )>

An element of type contact must contain 3 sub elements, namely name,

address, and telephone in exactly that order.

eg: <contact>

<name> James Thomas</name>

<address>Bangalore</address>

< telephone>2226473</telephone>

</contact>

Element Type Declarations (contd.)


2. <!ELEMENT contact (name, address?, telephone )>

• An element of type contact can contain three sub elements

• Firstly it must have a name element

• This is optionally followed by an address element

• Lastly a telephone element

eg: <contact>

<name> James Thomas</name>

<telephone>2226473</telephone>

</contact>


3. <!ELEMENT fruit(apple/orange)>

An element of type fruit contains either a single apple element or a single

orange element

4. <!ELEMENT fruit(apple/orange)+>

An element of type fruit contains one or more sub elements that are either

apple element or orange elements

eg : <fruit>

<apple> ----------</apple> <fruit>

<apple>-----------</apple> Or <orange>--------</orange>

<orange>---------</orange> </fruit>

</fruit>


5. <!ELEMENT fruit(apple/orange)*>

An element of type fruit contains zero or more sub elements that are either

apple element or orange element

eg : <fruit>

</fruit>

6. <!ELEMENT InStock EMPTY>

An element of type InStock does not contain anything

eg : <InStock/>


7. <!ELEMENT para(#PCDATA| list)*>

An element of type para contains a mixture of character and list elements

in any order.

eg : <para> <para> XML is a frame work

Here is my list </para> Or </para>

<list> ------ </list>

</para>

Or

<para>

<list> ------</list>

</para>


8. <!element InStock EMPTY>

•This is an error because the keyword “ELEMENT” must always be in

uppercase

• This is for all XML Keywords

Attribute List Declarations

• Attributes have to be declared in the DTD for the XML parser to check for

validity

• An attribute list declaration has four aspects

• The element type to which it belongs

• What the attribute is named

• What type of data the attribute value can contain

• How assignments to the attribute are treated by the parser ie. What to do if

a

value is not supplied

Declaring an Attribute’s Name and associating an element type

<!ATTLIST product

name…

color…

>

An element of type product has two attributes known as name and color…

eg:- <product name=”Parker” color=”Black”>

Attribute Types

• There are different types of attributes

• There is a plain value attribute known as a CDATA attribute

• This is declared using the CDATA keyword

• A list of permissible values for an attribute can be supplied using an

enumerated type attribute.

Attribute Type Declaration

1. <!ATTLIST product name CDATA -->

An element of type product has an attribute known as name, whose

value

can be any string of characters

2. <!ATTLIST product name CDATA …. color(red/green)--->

An element of type product has two attributes known as name and

color.

The color attribute value must be either the string “red” or the string

“green”. Eg: <product name=”Hero Honda” color=”red”>

Attribute Type Declaration (contd.)

3. <!ATTLIST product code ID ---->

An element declared of type product has an attribute known as code.

The values of the code, attribute must be unique among attributes of

the ID type across the entire XML document.

Eg: <product code=”B42”>

Attribute Defaults

• The four flavors of attribute default are

• A value must be supplied (Required attribute)

• A value may be supplied but need not be (Implied attribute)

• The value is fixed in the DTD (Fixed attribute )

• In the absence of value use the one given in the DTD.

Attribute Defaults (contd.)

1. <!ATTLIST product name CDATA #REQUIRED>

An element of types product has an attribute known as name, whose

value can be any string of characters. A value for this attribute must

be supplied when it is used in an XML document.

2. <!ATTLIST product name CDATA “IBMPC” >

An element of type product has an attribute known as name. The name

attribute value can have any string of characters. In the absence of a

value for the attributes in the document, use the default value

“IBMPC” Eg:<product name =”Turbo”>


3. <!ATTLIST product color(red/green) “red”) >

An element of type product has an attribute named color. The color

attribute must be either the string “red” or the string “green”. In the

absence of a value for the attribute in the document, use the default

value “red” E.g.: <product color=”red”>

4. <!ATTLIST product color(red/green) ) # REQUIRED >


attribute must be either the string “red” or the string “green”. A value

must be supplied when the element is used in a document.

Eg: <product color=”red”>


5. <!ATTLIST product color(red/green) ) # IMPLIED >


attribute must be either the string “red” or the string “green”. If a

value is not supplied leave it up to the XML application to decide what

to do.

e.g : <product color=”red”>

6. <! ATTLIST product name CDATA # FIXED “IBMPC” >

An element of type product has an attribute known as name. The value

of this attribute is fixed to the value “IBMPC”. Any other value is an

error.

Eg: <product name=”IBMPC”>

Entity declarations

• Entity takes a verity of forms and can be classified in various ways.

1. <!ENTITY spbm “Stately, plump, Black, Mulligan” >

There is an entity known as spbm when referenced in an XML

document the parser will insert the replacement text Stately, plump,

Black, Mulligan

Eg: <Ulysses> &spbm; stepped ….

Entity declarations (contd.)

2. <!ENTITY chapter1 SYSTEM http://www.digitome.com/chap1.xml>

There is an entity known as chapter1. When referenced in an XML

document, the parser will insert the contents of the file

http://www.digitome.com/chap1.xml.

Eg: <Ulysses> &chapter1;

Viewing XML Document in an HTML browser

• There are mainly two methods of displaying XML Document in an HTML

browser

1. Displaying XML in an HTML browser with Data Source Object

technology (DSO)

2. Converting XML to HTML via the XSL Stylesheet Language

Displaying XML in an HTML browser with Data Source Object Technology

• Microsoft Internet Explorer contains built in XML parser known as MSXML

• The Internet Explorer uses a technology called Data Source Objects

• The original intent of Data Source Object was to easily integrate relational

database data and the Web

• The Internet Explorer uses a XMLDSO applet to map XML to HTML

•The following is an XML example to be shown in a browser

The XML part

<?xml version =”1.0”?><PSC>

<PC><NAME> IBM PC </NAME><CAPACIY> 100 </CAPACITY><PRICE> 20000</PRICE>

</PC><PC>

<NAME> COMPAC PC </NAME><CAPACIY> 200 </CAPACITY><PRICE> 30000</PRICE>

</PC> <PC>

<NAME> SONY PC </NAME><CAPACIY> 300 </CAPACITY><PRICE> 40000</PRICE>

</PC></PCS>

The HTML part

<html>

<head>

<title> Example 1 </title>

<BODY>

<h1> Example 1 </h1>

<P>

XML catalog displayed in an HTML table using Data Binding

<applet code =com.xml.dso. XMLDSO.class width-100% height=25

id=xmldso >

<PARAM NAME=”url” VALUE=”cat.xml” >

</applet>

The HTML part (contd.)

<table id=table border=2 width=100% datasrc=#xmldso><thead>

<th> Name<th>Capacity<th>price

</thead><tr><td valign=top> <div datafld= NAME></td><td valign=top> <div datafld= CAPACITY></td><td valign=top> <div datafld= PRICE></td></tr>

</table> </BODY></html>

PCS

PC

HTML

table

cellcellcell

row

name pricecapacity

XML DSO

Applet

Using XMLDSO to connect XML elements with HTML

Displaying XML in an HTML browser with Data Source Object Technology

• The datasrc attribute is used to connect the table to the applet with the id

xmldso

• The datafld attribute is used to map the xml data to the HTML table

•The XMLDSO applet acts as a glue that binds the name element of the source

XML document to the first cell of the HTML table row

• The capacity element of the source XML document is bound to the second

cell

of the HTML table row

Storing XML in an HTML document

• XMLDSO can also have XML data provided to it as part of the HTML

page rather than accessing it externally

• The source XML can be embedded within the applet element

• To allow the applet to access the HTML page set the MAYSCRIPT

attribute to TRUE

Storing XML in an HTML document (contd.)

<html> <head> <title> Example 1 </title> <BODY> <h1>Example 1 </h1> <P> XML Catalog displayed in an HTML table using XML Data Binding <applet code= com.ms.xml.dso. XMLDSO.class width=100% height=25 id=xmldso mayscript=TRUE >  <?xml version =”1.0” ? ><PSC>

<PC><NAME> Acme Blaster </NAME><CAPACIY> 100 </CAPACITY><PRICE> 2000</PRICE>

</PC>

<PC><NAME> Speedy PC </NAME><CAPACIY> 200 </CAPACITY><PRICE> 4000</PRICE>

</PC> <PC>

<NAME> Gonzo PC </NAME><CAPACIY> 300 </CAPACITY><PRICE> 5000</PRICE>

</PC> </PCS></applet><!--table declaration as in Example 1 -- > <table id=table border=2 width=100% datasrc=#xmldso>

<thead><th> Name<th>Capacity<th>Price

</thead>

Displaying XML documents in a browser using XML tag

• Internet Explorer 5 and higher version allows XML document to be

embedded into an HTML document

• The <XML> tag is used to mark the beginning of the XML document and

</XML> tag is used to mark the end

• This type of XML representation in an HTML page is called data island

• For data islands the Attribute ID is set to “xml Doc”

• In the HTML file a DATASRC attribute which is set to “#xmlDoc” is added

to the table element’s start tag

Converting XML to HTML with XSL

• An XSL style sheet consists of a set of rules that tell an XSL processor how

to

convert an XML document into a displayable form on a browser

• XSL can be used to produce style sheets that are independent of any one

output notation

• A single XSL style sheet can be used to target multiple out put notations

such

as HTML, TeX, RTF and so on

Converting XML to HTML with XSL (contd.)

• As the HTML output is a major use of XSL a number of HTML specific

features have been built directly into the XSL language

• An XSL style sheet is based on the idea of rules that trigger when the

specified elements are encountered in an XML document

• The rule specifies what should be generated in the HTML output

• XSL can be used to produce new results by performing calculations on the

XML data

PCS

PC

HTML

table

cellcellcell

row

name pricecapacity

XSL

Processor

Generating HTML from XML with XSL

XSL Stylesheet

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