DOM. DOM: Document Object Model from Dietel chapter 8 XML when parsed is represented as a tree structure in memory with elements attributes and content

DOM

DOM: Document Object Model from Dietel chapter 8

• XML when parsed is represented as a tree structure in memory with elements attributes and content as tree nodes.

• XML is dynamic, a programmer can add or remove data, query for data as you would with a database.

• W3C provides a document object model – a standard for constructing the tree in memory. A parser following this guideline in a DOM-parser.

• A DOM parser exposes (makes available) a programmatic library that allows data in xml to be manipulated by manipulating the treenodes.

MS XML 6.0 insert

Download available at ms

Note: Peltzer text uses DOM object 4.0 but I could only get 3.0 to work

Comes with a help file (sdk)

A jscript<HTML><HEAD><TITLE>Displaying a Simple DOM Document in a Browser Popup</TITLE><SCRIPT LANGUAGE="JScript">function displayXml() { var xmldoc = new ActiveXObject("MSXML2.DOMDocument.3.0"); xmldoc.load("authors.xml"); alert(xmldoc.xml);}</SCRIPT></HEAD><BODY><BUTTON onClick="displayXml();">Display XML</BUTTON></BODY></HTML>

The xml (from our Peltzer text)<Authors> <AuthorInfo> <AuthorID>101</AuthorID> <AuthorFName>Dwight</AuthorFName> <AuthorLName>Peltzer</AuthorLName> <AuthorAddress>PO Box 516</AuthorAddress> <Auth_City>Some City</Auth_City> <Au_State>NY</Au_State> <Au_Zip>11564</Au_Zip> <BusinessTelNo>516-111-1234</BusinessTelNo> <Title>Professor of Computer Science</Title> <Employer>Tech University</Employer> </AuthorInfo> <AuthorPublisherInfo> <Publisher>Addison Wesley</Publisher> <Editor>MSR</Editor> <Address>25 Main Street Street</Address> <City>Major City</City> <State>MA</State> </AuthorPublisherInfo> <BookInfo> <Title>XML Language Mechanics</Title> <Pages> 450</Pages> <PublishDate>Summer 2003</PublishDate> <ISBN>0-201-77168-3</ISBN> <Category>XML Markup Language</Category> <NumChapters>12</NumChapters> <AdditionalFeatures>Self-Review Exercises and Projects</AdditionalFeatures> <SoftwareTools>Evaluation copy of XML Spy</SoftwareTools> </BookInfo></Authors>

Run the jscript (html) in IE

Display generates popup window

In Javascript, use loadXML to load a file or a string into ActiveXObject (DOMDocument)

<HTML><HEAD><TITLE>Displaying a Simple DOM Document in a Browser Popup</TITLE><SCRIPT LANGUAGE="JScript">function displayXml() { var xmldoc = new ActiveXObject("MSXML2.DOMDocument.3.0"); xmldoc.loadXML("<root><child></child></root>"); alert(xmldoc.xml);}</SCRIPT></HEAD><BODY><BUTTON onClick="displayXml();">Display XML</BUTTON></BODY></HTML>

Example script<html><body><script language="JavaScript"> objDOM = new ActiveXObject("Msxml2.DOMDocument.3.0"); objDOM.async = false; var objNode; var objText; objNode = objDOM.createElement("root"); objText = objDOM.createTextNode(" root AuthorElement"); objDOM.appendChild(objNode); objNode.appendChild(objText); alert(objDOM.xml); </script></body></html>

displaying a (really short DOM xml) document in javascript

Javascript to display nodes and content

<html><body><script type="text/vbscript">Text="<h1>Pastry 4 U</h1>"document.write(Text)set xmlDoc=CreateObject("Msxml2.DOMDocument.3.0")xmlDoc.async="false"xmlDoc.load("pastry.xml")for each n in xmlDoc.documentElement.childNodes document.write(n.nodename) document.write(": ") document.write(n.text) document.write("<br>")next</script></body></html>

Running on pastry.xml

Another example to display note contents

The script<html><head><SCRIPT LANGUAGE="JScript">function displayXml() {var xmlDoc = new ActiveXObject("Msxml2.DOMDocument.3.0")xmlDoc.async="false"xmlDoc.load("note.xml")to.innerText =xmlDoc.getElementsByTagName("to").item(0).textfrom.innerText=xmlDoc.getElementsByTagName("from").item(0).textheader.innerText=xmlDoc.getElementsByTagName("heading").item(0).textbody.innerText=xmlDoc.getElementsByTagName("body").item(0).text}</script></head><body bgcolor="white"><BUTTON onClick="displayXml();">Display XML</BUTTON><h1>DP Software</h1><b>To: </b><span id="to"></span><br><b>From: </b><span id="from"></span><hr><b><span id="header"></span></b><hr><span id="body"></span></body></html>

The note(.xml)<note><to>Bob</to><from>Joe</from><heading>important news!</heading><body>CSCI 345 assignment is due!!!</body></note>

Vb script: get the root and some other elements (see next slide for script)

script<html> <head> <title>DOM Invoice</title> </head> <body> <script type="text/vbscript"> set xmlDoc = CreateObject("Msxml2.DOMDocument.3.0") xmlDoc.async="false" xmlDoc.load("authors.xml") document.write("<h1>This is the root element</h1>") alert(xmlDoc.documentElement.nodeName) alert(xmlDoc.documentElement.childNodes(0).nodeName) alert(xmlDoc.documentElement.childNodes.item(0).text) </script> </body></html>

Authors.xml…the rest in notes• <Authors> • <AuthorInfo>• <AuthorID>101</AuthorID>• <AuthorFName>Dwight</AuthorFName>• <AuthorLName>Peltzer</AuthorLName>• <AuthorAddress>PO Box 516</AuthorAddress>• <Auth_City>Some City</Auth_City>• <Au_State>NY</Au_State>• <Au_Zip>11564</Au_Zip>• <BusinessTelNo>516-111-1234</BusinessTelNo>• <Title>Professor of Computer Science</Title>• <Employer>Tech University</Employer>• •

VBScript to pluck element names and text from xml

The xml

<root>

<TeacherElement>CSCI</TeacherElement>

<TeacherFName>Dennis</TeacherFName>

<TeacherLName>Higgins</TeacherLName>

<TeacherOffice>Fitzelle 239</TeacherOffice>

<TeacherPhone>3552</TeacherPhone>

</root>

vbscript<script type="text/vbscript">set xmlDoc=CreateObject("Msxml2.DOMDocument.3.0")xmlDoc.async="false"xmlDoc.load("teacherinfo.xml")document.write(xmlDoc.documentElement.childNodes(0).nodeName)document.write(":")document.write(xmlDoc.documentElement.childNodes(0).text)document.write("<br />")document.write(xmlDoc.documentElement.childNodes(0).nextSibling.nodeName)document.write(":")document.write(xmlDoc.documentElement.childNodes(0).nextSibling.text)document.write("<br />")document.write(xmlDoc.documentElement.childNodes(2).nodeName)document.write(":")document.write(xmlDoc.documentElement.childNodes(2).text)document.write("<br />")document.write(xmlDoc.documentElement.childNodes(3).nodeName)document.write(":")document.write(xmlDoc.documentElement.childNodes(3).text)document.write("<br />")document.write(xmlDoc.documentElement.childNodes(4).nodeName)document.write(":")document.write(xmlDoc.documentElement.childNodes(4).text)document.write("<br />")</script>

Create an entire document

The javascript<HTML><HEAD><TITLE>DOM Demo</TITLE><SCRIPT language="JavaScript"> var objDOM; objDOM = new ActiveXObject("Msxml2.DOMDocument.3.0"); objDOM.async = false; var objNode; var objFragment;  objNode = objDOM.createElement("root"); objDOM.appendChild(objNode);  objFragment = objDOM.createDocumentFragment();  objNode = objDOM.createElement("FName");  objFragment.appendChild(objNode);  objFragment.firstChild.appendChild(objDOM.createTextNode("Dennis")); objNode = objDOM.createElement("LName");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("Higgins"));objNode = objDOM.createElement("Publisher");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("WhoKnowzPress")); objNode = objDOM.createElement("Address");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("592 Cty Rte 5"));objNode = objDOM.createElement("City");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("Otego"));objNode = objDOM.createElement("State");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("NY"));objNode = objDOM.createElement("ZipCode");objFragment.appendChild(objNode);objFragment.lastChild.appendChild(objDOM.createTextNode("13825"));objDOM.documentElement.appendChild(objFragment); alert(objDOM.xml);</SCRIPT></HEAD><BODY> <P>Building an XML Document.</P></BODY></HTML>

Linked at…

DOM from javascript

A Javascript form: slide 1

• The javascript code is in notes for this slideLink is: http://employees.oneonta.edu/higgindm/internet%20programming/jsDataFromForm2.html

http://employees.oneonta.edu/higgindm/internet%20programming/jsDataFromForm2.html

http://employees.oneonta.edu/higgindm/internet%20programming/jsDataFromForm2.html

A Javascript form: slide 2

DOM structure using javascript DOM.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head> <title>A DOM Example</title></head><body><script type = "text/javascript" language = "JavaScript"> var xmlDocument = new ActiveXObject( "Microsoft.XMLDOM" ); xmlDocument.load( "article.xml" ); // get the root element var element = xmlDocument.documentElement; document.writeln( "<p>Here is the root node of the document:" ); document.writeln( "<strong>" + element.nodeName + "</strong>" ); document.writeln( "<br>The following are its child elements:" ); document.writeln( "</p><ul>" ); // traverse all child nodes of root element for ( i = 0; i < element.childNodes.length; i++ ) { var curNode = element.childNodes.item( i ); // print node name of each child element document.writeln( "<li><strong>" + curNode.nodeName + "</strong></li>" ); }

DOM.html file continued

document.writeln( "</ul>" ); // get the first child node of root element var currentNode = element.firstChild; document.writeln( "<p>The first child of root node is:" ); document.writeln( "<strong>" + currentNode.nodeName + "</strong>" ); document.writeln( "<br>whose next sibling is:" ); // get the next sibling of first child var nextSib = currentNode.nextSibling; document.writeln( "<strong>" + nextSib.nodeName + "</strong>." ); document.writeln( "<br>Value of <strong>" + nextSib.nodeName + "</strong> element is:" ); var value = nextSib.firstChild; // print the text value of the sibling document.writeln( "<em>" + value.nodeValue + "</em>" ); document.writeln( "<br>Parent node of " ); document.writeln( "<strong>" + nextSib.nodeName + "</strong> is:" ); document.writeln( "<strong>" + nextSib.parentNode.nodeName + "</strong>.</p>" );</script></body></html>

Running DOM.html on article.xml

<?xml version = "1.0"?>

<article> <title>Simple XML</title> <date>December 6, 2000</date> <author> <fname>Tem</fname> <lname>Nieto</lname> </author> <summary>XML is pretty easy.</summary> <content>Once you have mastered HTML, XML is easily learned. You must remember that XML is not for displaying information but for managing information. </content></article>

Running DOM.html (opens article.xml)

javascript

• modification of javascript program in Deitel text (in notes) lists children of root element and children of each of these.

• run on myclass.xml database

DOM for myclass.xml (from prev chpt notes)

Replacing text in an xml document and rewriting the file

• Dietel frequently uses the class com.sun.xml.tree.XmlDocument. This class is not part of java and you may (will!) have a hard time getting hold of it. It is nice, because it can be cast as a PrintWriter to write an xml file out. However, it is purposely not included in java because it is an internal class and subject to change. I figured out another way to do this using the transformer class, which is part of java. My way, unfortunately uses more code, so there is room for improvement.

• My code appears in the notes. Here are the two changes to the text version:

• In header:

import javax.xml.transform.*;

import javax.xml.transform.dom.DOMSource;• In code, to write file

StreamResult result = new StreamResult(new FileOutputStream("tmp.xml"));

transformer.transform(source, result);

Original and rewritten xml

• Original:• <?xml version="1.0" encoding="UTF-8"?>

• • • <!DOCTYPE myMessage• [• <!ELEMENT myMessage ( message )>• <!ELEMENT message ( #PCDATA )>• ]>

• <myMessage>• • <message>New Changed

Message!!</message>

• </myMessage>

• New version. BTW, LFs are not in file!!!<?xml version="1.0" encoding="UTF-8"?><myMessage> <message>some string</message></myMessage>

A java program to create an xml fileBuildXML.java

• The java program in notes creates the xml file (tmp2.xml) below. Uses transformer instead of XMLDocument class.

<?xml version="1.0" encoding="UTF-8"?><root><contact gender="F"><FirstName>Sue</FirstName><LastName>Green</LastName></contact><?myInstruction action silent?><![CDATA[I can add <, >, and ?]]></root>

Traversing the DOM tree with a java program: Input file

• Uses the xml file simpleContact.xml<?xml version = "1.0"?><!DOCTYPE contacts [ <!ELEMENT contacts ( contact+ )> <!ELEMENT contact ( FirstName, LastName )> <!ATTLIST contact gender ( M | F ) "M"> <!ELEMENT FirstName ( #PCDATA )> <!ELEMENT LastName ( #PCDATA )>]><contacts> <contact gender = "M"> <FirstName>John</FirstName> <LastName>Black</LastName> </contact> <contact gender = "F"> <FirstName>Johanna</FirstName> <LastName>Nally</LastName> </contact></contacts>

Commandline

• Java TraverseDOM simpleContact.xml

Traversing the DOM tree with a java program: Output

C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>java TraverseDOM simpleContact.xmlDocument node: #documentRoot element: contactsElement node: contactsElement node: contact Attribute: gender ; Value = MElement node: FirstName Text: JohnElement node: LastName Text: BlackElement node: contact Attribute: gender ; Value = FElement node: FirstName Text: JohannaElement node: LastName Text: NallyC:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>

DOS window for previous slide

DayPlanner using DOM

• The next example revisits the DayPlanner example (modified to use DOM)

• Examples from Deitel XML, examples, 8_18 directory.

DOMEcho02 uses JTree to display DOM tree structure

• Usage is

• Path>java DOMEcho02 file.xml

• Listing in notes

DOMEcho02 uses JTree to display DOM tree structure

DayPlanner using DOM

MyTransformer, another java program

• This program parses the xml, generates errors if any, displays the data content.

• MyTransformer appears in notes• To run:

Path>java MyTransformer input.xml output.xyz

MyTransformer, another java program:input

<?xml version = "1.0"?>

<!DOCTYPE contacts [ <!ELEMENT contacts ( contact+ )> <!ELEMENT contact ( FirstName, LastName )> <!ATTLIST contact gender ( M | F ) "M"> <!ELEMENT FirstName ( #PCDATA )> <!ELEMENT LastName ( #PCDATA )>]>

<contacts> <contact gender = "M"> <FirstName>John</FirstName> <LastName>Black</LastName> </contact> <contact gender = "F"> <FirstName>Johanna</FirstName> <LastName>Nally</LastName> </contact></contacts>

MyTransformer, another java program:output

<?xml version="1.0" encoding="UTF-8"?><contacts>

<contact gender="M"> <FirstName>John</FirstName> <LastName>Black</LastName> </contact> <contact gender="F"> <FirstName>Johanna</FirstName> <LastName>Nally</LastName> </contact></contacts>

Transformation2.java similar to TraverseDOM: listing in notes

Another example

The next few slides

• The contents of the next several slides appear in the notes of this ppt but are shown here in their entirety.

• They show an errorhandler class and all the code to traverse a DOM structure.

• Code is from Deitel.

ErrorHandlerimport org.xml.sax.ErrorHandler;import org.xml.sax.SAXException;import org.xml.sax.SAXParseException;public class MyErrorHandler implements ErrorHandler { // throw SAXException for fatal errors public void fatalError( SAXParseException exception ) throws SAXException { throw exception; } public void error( SAXParseException e ) throws SAXParseException { throw e; } // print any warnings public void warning( SAXParseException err ) throws SAXParseException { System.err.println( "Warning: " + err.getMessage() ); }}

Imports for TraverseDOM

import java.io.*;

import org.w3c.dom.*;

import org.xml.sax.*;

import javax.xml.parsers.*;

import com.sun.xml.tree.XmlDocument;• Last import is not part of java• You will have to use my notes in previous slides

on how to write out a DOM document to a file.

TraverseDOMpublic class TraverseDOM { private Document document; public TraverseDOM( String file ) { try { // obtain the default parser DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); factory.setValidating( true ); DocumentBuilder builder = factory.newDocumentBuilder(); // set error handler for validation errors builder.setErrorHandler( new MyErrorHandler() ); // obtain document object from XML document document = builder.parse( new File( file ) ); processNode( document ); } catch ( SAXParseException spe ) { System.err.println( "Parse error: " + spe.getMessage() ); System.exit( 1 ); } catch ( SAXException se ) { se.printStackTrace(); } catch ( FileNotFoundException fne ) { System.err.println( "File \'" + file + "\' not found. " ); System.exit( 1 ); } catch ( Exception e ) { e.printStackTrace(); } }

processNodepublic void processNode( Node currentNode ) { switch ( currentNode.getNodeType() ) { // process a Document node case Node.DOCUMENT_NODE: Document doc = ( Document ) currentNode; System.out.println( "Document node: " + doc.getNodeName() + "\nRoot element: " + doc.getDocumentElement().getNodeName() ); processChildNodes( doc.getChildNodes() ); break; // process an Element node case Node.ELEMENT_NODE: System.out.println( "\nElement node: " + currentNode.getNodeName() ); NamedNodeMap attributeNodes = currentNode.getAttributes(); for ( int i = 0; i < attributeNodes.getLength(); i++){ Attr attribute = ( Attr ) attributeNodes.item( i ); System.out.println( "\tAttribute: " + attribute.getNodeName() + " ; Value = " + attribute.getNodeValue() ); }

processChildNodes( currentNode.getChildNodes() ); break; // process a text node and a CDATA section case Node.CDATA_SECTION_NODE: case Node.TEXT_NODE: Text text = ( Text ) currentNode; if ( !text.getNodeValue().trim().equals( "" ) ) System.out.println( "\tText: " + text.getNodeValue() ); break; } }

processChildNodespublic void processChildNodes( NodeList children ) { if ( children.getLength() != 0 )

for ( int i = 0; i < children.getLength(); i++) processNode( children.item( i ) ); } public static void main( String args[] ) { if ( args.length < 1 ) { System.err.println( "Usage: java TraverseDOM <filename>" ); System.exit( 1 ); } TraverseDOM traverseDOM = new TraverseDOM( args[ 0 ] ); }}

Installing JDOM

• Read the readme file

• Run ant build

• Copy jdom.jar where you want it

• Edit classpath environment var from control panel/system/advanced/ to contain

Path…\org\jdom\jdom.jar

XSLTransform in JDOM samples prints html to output (this is just some of the output)

C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>java XSLTransform catalog.xml catalog.xsl<?xml version="1.0" encoding="UTF-8"?><html> <head> <title>Small chamber ensembles - 2-4 Players by New York Women Composers</title> </head> <body> <h1>Small chamber ensembles - 2-4 Players by New York Women Composers</h1> <h3>Trio for Flute, Viola and Harp</h3> <ul> <li>(1994)</li> <li>13'38"</li> <li>fl, hp, vla</li> <li>Theodore Presser</li> </ul> <p>Premiered at Queens College in April, 1996 by Sue Ann Kahn, Christine Ims, and Susan Jolles. In 3 movements :

mvt. 1: 5:01 mvt. 2: 4:11 mvt. 3: 4:26</p> <h3>Charmonium</h3> <ul> <li>(1991)</li> <li>9'</li> <li>2 vln, vla, vc</li> <li /> </ul> <p>Commissioned as quartet for the Meridian String Quartet. Sonorous, bold. Moderate difficulty. Tape available.</p> <h3>Invention for Flute and Piano</h3> <ul> <li>(1994)</li> <li /> <li>fl, pn</li> <li /> </ul>

JDOM comes with many demo programs: here is some of the DescendantDemo

outputC:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>java DescendantDemo web.xmlAll content:[Comment: ][Element: <web-app/>][Text: ][Element: <servlet/>][Text: ][Element: <servlet-name/>][Text: snoop ][Text: ][Element: <servlet-class/>][Text: SnoopServlet ][Text: ][Text: ][Element: <servlet/>][Text: ][Element: <servlet-name/>][Text: file ][Text: ]

continued<servlet-mapping> <servlet-name> mv </servlet-name> <url-pattern> *.wm </url-pattern> </servlet-mapping>

<distributed />

<security-role> <role-name> manager </role-name> <role-name> director </role-name> <role-name> president </role-name> </security-role>

</web-app>

C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>

SAXBuilder output (run on birds.xml in notes): How to build a JDOM from a SAX parser example

C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>java SAXBuilderDemo birds.xml true<?xml version="1.0" encoding="UTF-8"?><Class> <Order Name="TINAMIFORMES"> <Family Name="TINAMIDAE"> <Species Scientific_Name="Tinamus major">Great Tinamou.</Species> <Species Scientific_Name="Nothocercus">Highland Tinamou.</Species> <Species Scientific_Name="Crypturellus soui">Little Tinamou.</Species> <Species Scientific_Name="Crypturellus cinnamomeus">Thicket Tinamou.</Species> <Species Scientific_Name="Crypturellus boucardi">Slaty-breasted Tinamou.</Species> <Species Scientific_Name="Crypturellus kerriae">Choco Tinamou.</Species> </Family> </Order>

SAXBuilder codeimport java.io.*;import org.jdom.*;import org.jdom.input.*;import org.jdom.output.*;/** * <p><code>SAXBuilderDemo</code> demonstrates how to * build a JDOM <code>Document</code> using a SAX 2.0 * parser. * </p>*/public class SAXBuilderDemo { /** * <p> * This provides a static entry point for creating a JDOM * <code>{@link Document}</code> object using a SAX 2.0 * parser (an <code>XMLReader</code> implementation). * </p> * * @param args <code>String[]</code> * <ul> * <li>First argument: filename of XML document to parse</li> * <li>Second argument: optional boolean on whether to expand * entities</li> * <li>Third argument: optional String name of a SAX Driver class * to use</li> * </ul> */

SAXBuilder cont.public static void main(String[] args) { if ((args.length < 1) || (args.length > 3)) { System.out.println( "Usage: java SAXBuilderDemo " + "[XML document filename] ([expandEntities] [SAX Driver Class])"); return; } boolean expandEntities = true;

// Load filename and SAX driver class String filename = args[0]; String saxDriverClass = null; if (args.length > 1) { if (args[1].equalsIgnoreCase("false")) { expandEntities = false; } if (args.length > 2) { saxDriverClass = args[2]; } } // Create an instance of the tester and test try { SAXBuilder builder = null; if (saxDriverClass == null) { builder = new SAXBuilder(); } else { builder = new SAXBuilder(saxDriverClass); } builder.setExpandEntities(expandEntities); Document doc = builder.build(filename); XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat()); //outputter.setExpandEmptyElements(true); outputter.output(doc, System.out); } catch (JDOMException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }}

Documents

DOM. DOM: Document Object Model from Dietel chapter 8 XML when parsed is represented as a tree structure in memory with elements attributes and content