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DOM

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.

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DOM

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  1. DOM

  2. 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.

  3. 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

  4. Comes with a help file (sdk)

  5. 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>

  6. 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>

  7. Run the jscript (html) in IE

  8. Display generates popup window

  9. 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>

  10. 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>

  11. displaying a (really short DOM xml) document in javascript

  12. 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>

  13. Running on pastry.xml

  14. Another example to display note contents

  15. 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).text from.innerText= xmlDoc.getElementsByTagName("from").item(0).text header.innerText= xmlDoc.getElementsByTagName("heading").item(0).text body.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>

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

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

  18. 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>

  19. 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>

  20. VBScript to pluck element names and text from xml

  21. The xml <root> <TeacherElement>CSCI</TeacherElement> <TeacherFName>Dennis</TeacherFName> <TeacherLName>Higgins</TeacherLName> <TeacherOffice>Fitzelle 239</TeacherOffice> <TeacherPhone>3552</TeacherPhone> </root>

  22. 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>

  23. Create an entire document

  24. 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; <!-- create root element--> objNode = objDOM.createElement("root"); objDOM.appendChild(objNode); <!-- create the Document Interface Object to which other objects can be added --> objFragment = objDOM.createDocumentFragment(); <!-- Now create all child elements --> objNode = objDOM.createElement("FName"); <!-- append the child node --> objFragment.appendChild(objNode); <!-- create the text node for the child elements; Note the firstChild specifier --> 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")); <!-- Finally add the elements to our document root element --> objDOM.documentElement.appendChild(objFragment); alert(objDOM.xml); </SCRIPT> </HEAD> <BODY> <P>Building an XML Document.</P> </BODY> </HTML>

  25. Linked at…

  26. DOM from javascript

  27. A Javascript form: slide 1 • The javascript code is in notes for this slideLink is: http://employees.oneonta.edu/higgindm/internet%20programming/jsDataFromForm2.html

  28. A Javascript form: slide 2

  29. DOM structure using javascriptDOM.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>" ); }

  30. 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>

  31. Running DOM.html on article.xml <?xml version = "1.0"?> <!-- Fig. 8.2: article.xml --> <!-- Article formatted with XML --> <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>

  32. Running DOM.html (opens article.xml)

  33. 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

  34. DOM for myclass.xml (from prev chpt notes)

  35. 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);

  36. Original: <?xml version="1.0" encoding="UTF-8"?> <!-- Fig. 8.12 : intro.xml --> <!-- Simple introduction to XML markup --> <!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"?> <!-- Fig. 8.12 : intro.xml --> <!-- Simple introduction to XML markup --> <myMessage> <message>some string</message> </myMessage> Original and rewritten xml

  37. 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> <!--This is a simple contact list--> <contact gender="F"> <FirstName>Sue </FirstName> <LastName>Green</LastName> </contact><?myInstruction action silent?> <![CDATA[I can add <, >, and ?]]> </root>

  38. Traversing the DOM tree with a java program: Input file • Uses the xml file simpleContact.xml <?xml version = "1.0"?> <!-- Fig 8.17 : simpleContact.xml --> <!-- Input file for traverseDOM.java --> <!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> <!---->

  39. Commandline • Java TraverseDOM simpleContact.xml

  40. Traversing the DOM tree with a java program: Output C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>java TraverseDOM simpleContact.xml Document node: #document Root element: contacts Element node: contacts Element node: contact Attribute: gender ; Value = M Element node: FirstName Text: John Element node: LastName Text: Black Element node: contact Attribute: gender ; Value = F Element node: FirstName Text: Johanna Element node: LastName Text: Nally C:\PROGRA~1\JAVA\JDK15~1.0_0\BIN>

  41. DOS window for previous slide

  42. DayPlanner using DOM • The next example revisits the DayPlanner example (modified to use DOM) • Examples from Deitel XML, examples, 8_18 directory.

  43. DOMEcho02 uses JTree to display DOM tree structure • Usage is • Path>java DOMEcho02 file.xml • Listing in notes

  44. DOMEcho02 uses JTree to display DOM tree structure

  45. DayPlanner using DOM

  46. 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

  47. MyTransformer, another java program:input <?xml version = "1.0"?> <!-- Fig 8.17 : simpleContact.xml --> <!-- Input file for traverseDOM.java --> <!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> <!---->

  48. MyTransformer, another java program:output <?xml version="1.0" encoding="UTF-8"?><!-- Fig 8.17 : simpleContact.xml --><!-- Input file for MyTransformer.java --><contacts> <contact gender="M"> <FirstName>John</FirstName> <LastName>Black</LastName> </contact> <contact gender="F"> <FirstName>Johanna</FirstName> <LastName>Nally</LastName> </contact> </contacts><!---->

  49. Transformation2.java similar to TraverseDOM: listing in notes

  50. Another example

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