two types of xml parsers

8/19/2019 Two Types of XML Parsers

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Two types of XML parsers:

Validating Parser

• It requires document type declaration

• It generates error if document does not

o Conform with DTD and

o Meet XML validity constraints Non-validating Parser

• It checs well!formedness for "ml document• It can ignore e"ternal DTD

What is XML Parser?

XML Parser provides way how to access or modify data present in an XML document# $ava

provides multiple options to parse XML document# %ollowing are various types of parsers

which are commonly used to parse XML documents#

Types of parsers:

• Dom Parser - Parses the document &y loading the complete contents of the document

and creating its complete hiearchical tree in memory#

• !X Parser - Parses the document on event &ased triggers# Does not load the complete

document into the memory#

• "D#M Parser - Parses the document in similar fashion to D'M parser &ut in more

easier way#

• t!X Parser - Parses the document in similar fashion to ()X parser &ut in more

efficient way#

• XPath Parser ! Parses the XML &ased on e"pression and is used e"tensively in

con*uction with X(LT#

• D#M$" Parser ! ) *ava li&rary to parse XML+ XPath and X(LT using $ava Collections

%ramewor + provides support for D'M+ ()X and $)XP#

D#M-Do%&ment #'(e%t ModelThe Document '&*ect Model protocol converts an XML document into a collection of o&*ects in

your program# XML documents have a hierarchy of informational units called nodes, thishierarchy allows a developer to navigate through the tree looing for specific information#

-ecause it is &ased on a hierarchy of information+ the D'M is said to &e tree &ased# D'M is a

way of descri&ing those nodes and the relationships &etween them#



.ou can then manipulate the o&*ect model in any way that maes sense# This mechanism is also

nown as the /random access/ protocol+ &ecause you can visit any part of the data at any time#

.ou can then modify the data+ remove it+ or insert new data#

The XML D'M+ on the other hand+ also provides an )PI that allows a developer to add+ edit+

move+ or remove nodes in the tree at any point in order to create an application# ) D'M parser

creates a tree structure in memory from the input document and then waits for requests fromclient# ) D'M parser always serves the client application with the entire do%&ment no matter

how m&%h is a%t&ally needed &y the client# 0ith D'M parser+ method calls in client application

have to &e e"plicit and forms a ind of chained method calls#Document '&*ect Model is for defining the standard for accessing and manipulating XML

documents# XML D#M is used for

• Loading the "ml document

• )ccessing the "ml document

• Deleting the elements of "ml document

• Changing the elements of "ml document

)ccording to the D'M+ everything in an XML document is a node# It considers

• The entire document is a document node

• 1very XML element is an element node

• The te"t in the XML elements are te"t nodes

• 1very attri&ute is an attri&ute node

• Comments are comment nodes

D#M Levels

• Level 2 Core3 04C 5ecommendation+ 'cto&er 2667

It has feature for primitive navigation and manipulation of XML trees

other Level 2 features are3 )ll 8TML features• Level 9 Core3 04C 5ecommendation+ :ovem&er 9;;;

It adds :amespace support and minor new features

other Level 9 features are3 1vents+ <iews+ (tyle+ Traversal and 5ange

• Level 4 Core3 04C 0oring Draft+ )pril 9;;9

It supports3 (chemas+ XPath+ X(L+ X(LT

0e can access and parse the XML document in two ways3

Parsing&sing D#M )tree 'ased*

Parsing &sing !X )+vent 'ased*

Parsing the XML doc# using D'M methods and properties are called as tree 'ased approa%h

whereas using ()X =(imple )pi for Xml> methods and properties are called as event 'asedapproa%h,



teps to sing D#M Parser

Let?s note down some &road steps involved in using a D'M parser for parsing any XML file in *ava#

DOM based XML Parsing:(tree based)

$)XP is a tool+ stands for $ava )pi for Xml Processing+ used for accessing and manipulating "ml

document in a tree &ased manner#

The following D'M *avaClasses are necessary to process the XML document3

• Document-uilder%actory class creates the instance of Document-uilder#

• Document-uilder produces a Document =a D'M> that conforms to the D'M specification#

The following methods and properties are necessary to process the XML document3

Property Meaning

node:ame %inding the name of the node

node<alue '&taining value of the node parent:ode To get parnet node

child:odes '&tain child nodes

attri&utes %or getting the attri&utes values

Method Meaning

get1lement-yTag:ame=name> To access the element &y specifying its name

appendChild=node> To insert a child node

removeChild=node> To remove e"isting child node

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!%tiveX#'(e%t: It creates empty "ml

document o&*ect#

se separate f&n%tion for Loading an

XML do%&ment: two,html

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Use of properties and methods

Three.html

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>;Q#child:odes;Q#node<alue>,

! ! ! !! ! ! ! !! ! ! ! !! ! !

@scriptA

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We can access any XML element using the index value.

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.mlDo%/My0f&n%tion)1fa%&lty4,.ml2*3

valueB"mlDoc# get1lements-yTag:ame=Fname>,

document#write=Fvalue2Q#child:odes;Q#node<alue>,

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two types of xml parsers

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