document object model (dom): an abstract data structure for xml data alex dekhtyar department of...

Document Object Model (DOM):

An Abstract Data Structure for XML data

Alex DekhtyarAlex DekhtyarDepartment of Computer Department of Computer Science Science University of KentuckyUniversity of Kentucky

About

Jobs for B.S. graduates often require work with Jobs for B.S. graduates often require work with XMLXML

Teach XML in undergraduate curriculumTeach XML in undergraduate curriculum DatabasesDatabases Web ProgrammingWeb Programming Data StructuresData Structures

Outline

XML SyntaxXML Syntax

XML as a treeXML as a tree

Document Object Model (DOM)Document Object Model (DOM)

DOM APIDOM API

<faculty> <name> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

XML

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

Meta-language for encoding information

Information, content

XML elements

Opening tags: <name>Closing tags: <name/>Emply elements: <p/>

ordered

<faculty id =“27” > <name origin=“Ukraine”> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

XML

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

Meta-language for encoding information

Information, content

XML elements

AttributesAdditional informationunordered

Opening tags: <name>Closing tags: <name/>Emply elements: <p/>

ordered

<faculty id =“27” > <name origin=“Ukraine”> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

XML

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

Structure nested elements

Well-formed XML correctly nested elements

World Wide Web Consortium (W3C)

recommendation XML 1.0, 1998

APIAPI

XML and applications

documents data

XMLFiles

<?xml version=“1.0”><?xml version=“1.0”><r><r>

</r></r>

application

Parser InternalInternal data structuredata structure

APIAPI

XML and applications

documents data

XMLFiles

<?xml version=“1.0”><?xml version=“1.0”><r><r>

</r></r>

Parser InternalInternal data structuredata structure

application

XML and applications

InternalInternal data structuredata structure

APIAPI

Document Object Model (DOM)

W3C standard www.w3c.org/DOM

DOM Level 1 (core) – for XMLDOM Level 1 (core) – for XML

DOME Level 1 (HTML) – for HTML

Trees for XML<faculty id =“27” > <name origin=“Ukraine”> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

facultyfaculty

namename deptdept coursecourse

Trees for XML

<faculty id =“27” > <name origin=“Ukraine”> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

facultyfaculty

namename deptdept coursecourse

lastlastfirstfirst middlemiddle

Id=“27”

semsem titletitlecodecode

origin=“Ukraine”

AlexanderSpring 2007

M. Dekhtyar

Computer Science

CS 405Database Systems

Trees for XML

<faculty id =“27” > <name origin=“Ukraine”> <first> </first> <middle> </middle> <last> </last> </name> <dept> </dept> <course> <sem> </sem> <code> </code> <title> </title> </course> </faculty>

Alexander M. Dekhtyar

Computer Science

Spring 2007 CS405 Database systems

facultyfaculty

namename deptdept coursecourse

lastlastfirstfirst middlemiddle

Id=“27”

semsem titletitlecodecode

origin=“Ukraine”

AlexanderSpring 2007M. Dekhtyar

Computer Science

CS 405Database Systems

namename - Element node

Computer Science - Text node Id=“27” - Attribute node

facultyfaculty - Root node

Document Object Model

Abstract Data Type

Object-oriented

System of types/interfaces Attributes Methods

Functionality

facultyfaculty

namename deptdept coursecourse

lastlastfirstfirst middlemiddle

Id=“27”

semsem titletitlecodecode

origin=“Ukraine”

AlexanderSpring 2007

M. Dekhtyar

Computer Science

CS 405Database Systems

Creation of nodes

Insertion of nodes in into the DOM Tree

Traversal of the DOM Tree

DOM Type Structureinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface DocumentTypeDocumentType

interface interface CDATASectionCDATASection

… and a few more

subtype

interface interface NodeListNodeListlist of

interface interface NamedNodeMapNamedNodeMap

set of

interface Node

DOMString nodeName DOMString nodeValue short nodeTypeNode parentNode NodeList childNodes Node firstChildNode lastChild Node previousSiblingNode nextSiblingNamedNodeMap attributes Document ownerDocument

facultyfaculty

namename

firstfirst

origin=“Ukraine”

deptdept

documentdocument

middlemiddle

Node Typesinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface EntityEntity

interface interface CDATASectionCDATASection

… and a few more

subtype

nodeType

9

1

2

1

0

8

3

6

4(12 nodetypes altogether)

nodeName nodeValue

Tag null

AttName AttValue

#text content

interface Node methods

Node insertBeforeinsertBefore(in Node newChild, in Node refChild)Node replaceChildreplaceChild(in Node newChild, in Node oldChild)Node removeChildremoveChild(in Node oldChild)Node appendChildappendChild(in Node newChild) boolean hasChildNodeshasChildNodes() Node cloneNodecloneNode(in boolean deep)

DOM Type Structureinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface DocumentTypeDocumentType

interface interface CDATASectionCDATASection

… and a few more

subtype

interface interface NodeListNodeListlist of

interface interface NamedNodeMapNamedNodeMap

set of

interface DocumentAttributesDocumentType doctypeElement documentElement

Methods

documentdocument

DTDDTD

doctype

rootroot

Element createElement(in DOMString tagName)DocumentFragment createDocumentFragment() Text createTextNode(in DOMString data)Comment createComment(in DOMString data)CDATASection createCDATASection(in DOMString data) Attr createAttribute(in DOMString name)

NodeList getElementsByTagName(in DOMString tagname)

<a>

<a>

<a><a>

DOM Type Structureinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface DocumentTypeDocumentType

interface interface CDATASectionCDATASection

… and a few more

subtype

interface interface NodeListNodeListlist of

interface interface NamedNodeMapNamedNodeMap

set of

interface Elementinterface Element : Node { DOMString tagName;

DOMString getAttributegetAttribute(in DOMString name);

void setAttributesetAttribute(in DOMString name, in DOMString value) void removeAttributeremoveAttribute(in DOMString name)

Attr getAttributeNodegetAttributeNode(in DOMString name); Attr setAttributeNodesetAttributeNode(in Attr newAttr) Attr removeAttributeNoderemoveAttributeNode(in Attr oldAttr)

NodeList getElementsByTagNamegetElementsByTagName(in DOMString name)

};

Attribute management

DOM Type Structureinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface DocumentTypeDocumentType

interface interface CDATASectionCDATASection

… and a few more

subtype

interface interface NodeListNodeListlist of

interface interface NamedNodeMapNamedNodeMap

set of

DOM Type Structureinterface Nodeinterface Node

interface interface ElementElement

interface interface AttrAttr

interface interface DocumentDocument

interface interface DocumentTypeDocumentType

interface interface CommentComment

interface interface TextText

interface interface DocumentTypeDocumentType

interface interface CDATASectionCDATASection

… and a few more

subtype

interface interface NodeListNodeListlist of

interface interface NamedNodeMapNamedNodeMap

set of

interface NodeListinterface NodeList { Node itemitem(in unsigned long index); unsigned long lengthlength; }

interface NamedNodeMapinterface NamedNodeMap { Node getNamedItemgetNamedItem(in DOMString name); Node setNamedItemsetNamedItem(in Node arg); Node removeNamedItem(in DOMString name);

Node itemitem(in unsigned long index);

unsigned long lengthlength; };

Next…Implementations of DOM interfaces

1. Using pointers

nodes content

attributes

2. Using record arrays3. Wrappers over legacy implementations