exemel.ppt

7/27/2019 exemel.ppt

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Extensible Markup

Language


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Contents

Why XML? Introduction HTML & XML

Types of XML Documents Namespaces

DTD

Schema

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Why XML?

It is a standard, easily extensible way toencode information

To resolve issues in large scale electronicinformation publishing

To create richly structured arbitrarydocument

Due to its easy parseability, software cantransform it in countless ways

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Introduction

XML stands for eXtensible Markup Language A technology from W3C

A method of creating document with Userdefined tags

In XML, data speaks what it is? Not how itlooks

XML can serve web with HTML and WMLtransformation

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HTML & XML

Comparison


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HTML Data Sample

Following is an HTML Sample Code Guess what is talks about!!!

VishwanathanNalasupara

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Umm

There is some bold and italic text But, we could still guess what data it is

representing

Bold text Must be the name of some person

Italic text

Must be the name of some place Finally, Good guesses pays.

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Sample XML Document

Here is the XML version of the same data

VishwanathanNalasupara

Do you still need to guess what it is?

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Comparison

HTML Data Presentation

Un-Structured

Non-Case-Sensitive Vocabulary of build-in tags

No error checks

Current Version - 4.x Extension - .htm, .html

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Comparison

XML Data Definition

100% Structured100% Case-Sensitive

User defined tags

Checks for errors

Version since beginning - 1.0 Extension - .xml

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Types of XML

Documents


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Two Types of XML document

Well-Formed An XML document follows all the

structuredness rules of the XML language

Valid A well-formed XML document is Valid if it

conforms to its Vocabulary

Every valid XML document is a well-formedXML document but, every well-formeddocument is not a valid XML document

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Well-Formedness Rules

Document should contain at least Prolog

XML Declaration (Mandatory)

Root Element (Mandatory) All tags are grouped within a single tag

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Continued

Should follow rules given by W3C There can be only one root element

Root element should include all otherelements

Every element should have a closing tag

Empty elements should be self-closing

Proper nesting of tags should be there

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Continued

Attribute values should be enclosed indouble quotes

Naming rules should be followed forelements and attributes Should start with A-Z or a-z or _

Can contain A-Z or a-z or 0-9 or _ or - or .(dot)

Any external data embedded in XML shouldalso be well-formed

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Is it a Well-Formed Document?

Zubair Shaikh29

Mumbai

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Why to Validate XML Document?

Lets consider the Person example A well-formedness check will make it sure

that there is no syntax error but,

What if you want to make it sure, that The attribute value for gender is male/female

The name element is the first child of person

All the elements are appeared and that too inthe desired sequence

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Valid XML Document

Follows a vocabulary Vocabulary is a user defined set of elements

and rules such as

The element that can or must appear How often the element can appear

How the element can be nested

The allowable, required and defaultattributes

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Defining Vocabulary

Vocabulary can be defined using DTD - Document Type Definition

XSD - XML Schema Definition

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Namespaces


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Why Namespaces?

Naming standards to the element/attributeare too brittle

Element and Attribute names can beambiguous

There is no way to know if a name is alreadyin use

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Introduction

It is introduced to makes naming unique andfree of ambiguity

It refers to two-part name as QualifiedNames or QNames

It deals with the mechanics of associating aURI qualifier with element and attributenames URIs are used because they provide a unique

naming convention

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Qualified Names

QNames are used in place of element names QName have a prefix and a local part They are like

It can be interpreted as

{http://www.example.com/person}name

It is important to understand that the

significance of prefixes lies in the URI

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Declaring Namespaces

The syntax of namespace declaration is

The following example declare thenamespace person for URIhttp://www.example.com/persons

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An Example

Zubair29

Mumbai

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Default Namespace Example

Zubair

29Mumbai

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Document Type

Definition

DTD


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Why DTD?

A DTD adds syntactical requirements inaddition to the well-formed requirement It helps in eliminating errors when creating

or editing XML documents It clarifies the intended semantics It simplifies the processing of XML

documents

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Introduction

Document Type Definitions (DTDs) imposestructure on XML documents The DTD is a syntactic specification The DTD follows regular expressions

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Requirements

Consider the following example

Zubair Shaikh29

Mumbai

022-22872183

+91-9829748328

[email protected]

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Requirements

person is an element name, age and city appears in a sequence There can be one or more occurrences of

phone email is the optional element

Person can be either Indian or NRI

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Specifying the Structure

person

name,age,city

phone+

email?

indain|nri

To specify the person element

To specify the sequence of

name age and city

To specify one or moreoccurrences of phone

To specify email is optional

(Zero or One)To specify either indian or nri

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Summary of Regular Expressions

ee1,e2

e*e?e+

e1|e2

(e)

An elementSequence

Zero or more occurrencesZero or One occurrencesOne or more occurrencesEither

Grouping

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An Example

(indian|nri))>

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XML Schema Definition

Schema

S ?


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Why XML Schema?

Have you realized any issues with DTD? Is it an XML document

Need for Data types

Validating element values Specifying upper limit of occurrences

Defining custom types for similar elements

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I d i


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Introduction

XML Schema is an XML based alternative toDTD An XML vocabulary for expressing your

data's business rules Object-oriented'ish

With the support for data types

Better support for mixed content model

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XML Path

XPath

I t d ti


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Introduction

XPath is a W3C recommendation (1999) According to W3C

It is a Language for addressing path of anXML document

XPath models XML documents as trees ofnodes using the Document Object Model

XPath uses path expressions to locate nodeswith XML documents

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I t d ti


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Introduction

XPath is an efective and powerful way ofquery XML documents XPath is a language for specifying parts of an

XML document

XPath also inludes a library of standardfunctions for node-sets, strings, boolean andnumbers

XPath uses path expressions to identify XMLdocument parts

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A E l


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An Example

Java

Frank450

XMLMark390

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L ti N d


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Locating Nodes

Path = /library/book/price

JavaFrank

450

XML

Mark

390

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Wild C d


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Wild Cards

Path = /library/book/*

JavaFrank450

XML

Mark

390

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S l ti B h


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Selecting Branches

Path = /library/book[1]

JavaFrank450

XML

Mark

390

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S l ti B h


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Selecting Branches

Path = /library/book[last()]

JavaFrank450

XML

Mark

390

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S l t S l P th


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Select Several Paths

Path =/library/book/title|/library/book/price

Java

Frank

450

XML

Mark

390

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Selecting Attributes


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Selecting Attributes

Path = //book[@isbn=43-4749]

JavaFrank450

XML

Mark

390

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Location Paths


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Location Paths

One of the most important xpathexpressions is the location path. A location path expression results in a node

set Each location path consist of one or more

location steps

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Location Step Syntax


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Location Step Syntax

Each location step has An axis

A node test

One or more predicates (optional) Location step syntax

axisname::nodetest[predicate]

child::book[author=Mark]

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XPath Axis


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XPath Axis

There are several axes in XPath Each of which selects a different subset of

the nodes in the document

That is depending on the context node

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Location Path: Axes


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Location Path: Axes

Ancestor Ancestor-or-selfAttribute Child

Descendent Descendent-or-self

Following Following-sibling

Namespace Parent

Preceding Preceding-sibling

Self Sibling

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Location Path: Child Axis


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Location Path: Child Axis

The child axis with library context node

library

book book

title author price title author price

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Location Path: Sibling Axis


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Location Path: Sibling Axis

The preceding-sibling axis with pricecontext nodelibrary

book book

title author price title author price

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Location Path: Nodes


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Location Path: Nodes

There are seven types of node Root nodes

Element nodes

Text nodes Attribute nodes

Namespace nodes

Processing instruction nodes Comment nodes

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Location Path: Node Test


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Location Path: Node Test

Node test determine what kind of nodes beselected along a given axis The node test is applied to each node in the

axis Example location path with node test

child::foo - foo child element

parent::text() - text node of parent descendent::comment() - comment node

below

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Location Path: Predicates


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Location Path: Predicates

Predicate is a further test to retain nodes It filters the node set into a new node set Each node is evaluated in turn

If predicate is true for a given node, it is keptin the new node set

If false it is removed

Predicates consist of a well-formedexpressions

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Predicate Expressions


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Expression consist of boolean operators

functions

numbers, strings comparison operators

Example

child::book[author=Mike] descendent::book[position()=2]

descendent::library*attribute::type=isbn+

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Expressions describes a set of nodes in adocuments Path expression may be absolute or relative

Absolute begins from the root node /library/book/title

Relative begins from the context node

book/author

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Expressions


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Expressions

XPath supports four types of expression Numerical

+ - * div mod

Equality = !=

Relational

< > =

Boolean

and or

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Functions


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Functions

XPath defines a number of useful functionsfor converting and translating data Node set functions

count() - returns number of nodes in node set

String functions

concat() - returns the concatenations of all itsarguments

contains() - returns true if the second of 2 givenstrings is in the first

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Functions


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Functions

Number functions sum() - returns the total value of a set of numeric

values in a node set

Boolean functions

not() - returns true if the argument is false, andfalse if the argument is true

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Presenting XML

Presenting XML


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Presenting XML

XML data can be presented The available options for the same

CSS - Cascading Style Sheets

XSL - XML Stylesheet Language

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Cascading Style Sheet


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CSS can be used to present XML documentMost of the browsers supports CSS

Eg: MSIE, Firefox, Opera

CSS is used to view XML as if it were HTML A style must be defined for each of the XML

element

Or the browser displays it in its defaultformat

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All display characteristics of each elementmust be explicitly defined Elements are displayed in the order they are

encountered in the XML document No reordering of elements or other

processing is possible

Must put a processing instruction at the topof your XML file Below XML declaration

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XML Processing Instruction


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XML Processing Instruction

CSS is written in a separate fileSaved with the extension .css Below is an example of processing

instruction

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An Example


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An Example

Rosy Dsouza

Happy Diwali

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Style Sheet


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Style Sheet

greeting{display:block;

background-color:pink;

}

person{

font:20pt verdana;color:blue;

}

message{

font:24pt georgia;color:red;font-style:itlaic;

}

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XML Style Sheet

Language

Transformation

Introduction


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Introduction

XML Style Sheet Language - Transformation A markup language and programming

syntax for processing XML

Most often used to Transform XML to HTML to deliver to

standard web clients

Transform XML from one set of tag to

another

Transform XML into another syntax/system

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Introduction


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Introduction

An XML document is a collection of nodesthat can be identified, selected and actedupon using an XPath expression

XSLT is based on the process of matching

templates to nodes of the XML tree

An XSLT style sheet is a collection of

templates that act against specified nodes inthe XML source tree

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An Example


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An Example

Sam Mendes

Eid Mubarak

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Tree Nodes


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Tree Nodes

/ Root

greeting Root element

person message Child elements

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Templates


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Templates

A separate template is defined for eachelement Syntax for defining template

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Calling Templates


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g p

A template can call other templates

Tree Processing

Call templates of all the children nodes

Call all title templates of context node

Call the named template, regardless of the sourcetree

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Pull and Push Processing


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g

Push Processing of templates In this the source document controls the

order of processing

Eg:

Pull Processing of templates

It address particular element in the sourcetree regardless of the position

Eg:

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Selecting Element and Attributes


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g

To select the content of a particular elementor attribute element is

Takes xpath expression to search node

For selecting an attribute, attribute name

precedes with an @ symbol

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Decision Structure


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For processing data based on a specifiedcriteria XSL provides

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Looping & Sorting


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p g g

XSLT provides support for looping Looping too is using xpath expression for

selecting a node to perform operation oneach node

For looping XSL provide

For sorting

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XML Query Language

XQuery

Why XQuery?


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y y

One of the great strengths of XML is its

flexibility in representing many different

kinds of information from diverse sources

As increasing amounts of information are

stored, exchanged, & presented using XML

The ability to intelligently query XML datasources becomes increasingly important

To exploit this flexibility, an XML querylanguage must provide features forretrieving and interpreting information

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Querying XML Data


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y g

XPath Simple Navigation through the tree

XSLT

Recursive Traversal XQuery

The SQL of XML

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What is XQuery


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y

SQL for Database

SQL Database

XQuery for XML Document / Database

XML

DocumentXQuery or

Database

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Introduction


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XQuery is a query language for XML data

XQuery follows FLWR (flower)

FOR

LET WHERE

RETURN

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FLWOR


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FOR and/or LET Appear one or more times

WHERE

Optional RETURN

Always present

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An Example


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Java

Frank450

XMLMark390

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FOR


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FOR variable IN expressionFOR $x IN

doc(library.xml)/library/bookRETURN {$x}

Result:

Java

XML

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LET


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LET variable = expression

LET $x =

doc(library.xml)/library/bookRETURN {$x}

Result:

......

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Query Example


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Find all book titles priced more than 300FOR $x IN

doc(library.xml)/library/book

WHERE $x/price > 400

RETURN{$x/title}

Output:

Java

XML

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Query Example


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Find all book titles priced more than 300LET $x :=

doc(library.xml)/library/book[price > 300]

RETURN{$x/title}

Output:

JavaXML

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Thank You

Zubair Shaikh