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xml - Day 4

Goals

In this session you will:

Understand the DOM
Use the DOM to manipulate the XML document, add and delete elements

POST

CSS uses selectors to match elements to properties. What does XSLT use?
What is one of the theoretical advantages of XSL Formatting/Flow Objects over CSS?
In the expression "sort-by="+/-element" , what does the + and - signify?

Understanding the DOM

DOM provides generic access to DOM-compliant documents: add, edit, delete, manipulate

DOM is language-independent

The DOM is based on a tree view of your document. Nodes! Nodes! Nodes!

DOM useful for CSS, HTML, XML

DOM + client-side scripting + HTML = DHTML

DOM components There is a cheat sheet you can print in landscape mode.
- Document top-level view of the document, with access to all nodes (including root element)
  - createElement method - creates an element node
  - createAttribute method - creates an attribute node
  - createComment method - creates a comment node
  - getDocumentElement method - returns root element
  - appendChild method - appends a child node
  - getChildNodes method - returns child nodes
- Node represents a node - "A node is a reference to an element, its attributes, or text from the document."
  - cloneNode method - duplicates a node
  - getNodeName method - returns the node name
  - getNodeName method - returns the node's name
  - getNodeType method - returns the node's type
  - getNodeValue method - returns the node's value
  - getParentNode method - returns the node's parent's name
  - hasChildNodes method - true if has child nodes
  - insertBefore method - stuffs child in before specified child
  - removeChild method - removes the child node
  - replaceChild method - replaces one child with another
  - setNodeValue method - sets node's value
- attribute represents an attribute node -
  - getAttribute method - gets attribute!
  - getTagName method - gets element's name
  - removeAttribute method - deletes it
  - setAttribute method - sets att's value

Creating an XML document object

JavaScript: var myXO = new ActiveXObject("Microsoft.XMLDOM")
VBScript: set myXO = CreateObject("Microsoft.XMLDOM")
.asp: set myXO = Server.CreateObject("Microsoft.XMLDOM")
perl:

Adding in a new element

var link = document.createElement('a');
link.setAttribute('href', 'mypage.htm');

Where to put this new element?

locating a slot in the document

by location: document.childNodes[1].childNodes[0] ""Find the main document element (HTML), and find its second child (BODY), then look for its first child (DIV)" "
by ID: document.getElementById('myDiv').appendChild(txt);

Hiding an element

document.childNodes[1].childNodes[1].childNodes[0].style.display = "none"; (""=show)

Loading an XML document object into the parser

<script language="JavaScript"> (start javascript)
var xmlDoc = new ActiveXObject("Microsoft.XMLDOM") (create an instance of the document object)
xmlDoc.async="false" (wait until the document is loaded)
xmlDoc.load("petstore.xml") (load the doc into the
// ....... process the document in here somewhere
</script> (close up the javascript)

manually loading XML into the parser

// now create the DO
var xmlDoc = new ActiveXObject("Microsoft.XMLDOM")
xmlDoc.async="false"
xmlDoc.loadXML(text)
// ....... process the document
</script>

parseError object

document.write(xmlDoc.parseError.property)

errorCode: Returns a long integer error code
reason: Returns a string explaining the reason for the error
line: Returns a long integer representing the line number for the error
linePos: Returns a long integer representing the line position for the error
srcText: Returns a string containing the line that caused the error
url: Returns the url pointing the loaded document
filePos: Returns a long integer file position of the error

Traversing nodes

set xmlDoc=CreateObject("Microsoft.XMLDOM")
xmlDoc.async="false"
xmlDoc.load("note.xml")
for each x in xmlDoc.documentElement.childNodes
	document.write(x.nodename)
	document.write(": ")
	document.write(x.text)
	next

Calling XML nodes by name



 var xmlDoc = new ActiveXObject("Microsoft.XMLDOM")

xmlDoc.async="false"

xmlDoc.load("note.xml")

document.write(xmlDoc.getElementsByTagName("from").item(0).text)

Hands on!

build a simple XML page to simplify the process (root + three children with different names and different content)
build a DTD to validate the document
validate
start an html page to contain our javascript
jiggle IE preferences to show all errors
extract and print out the name of the root element
extract and print out the name[s] of the child[ren] (will require an iteration)
add an element
delete an element
Conclusion
XML definitions, manually created XML (elements, attributes) from data, validated with DTD, transformed with XSLT, manipulated the DOM.
Where to go from here
- other coursework
- outside work
  - SAX (simple API for xml) in place of DOM (particularly for large, read-only XML docs)
  - XPath, Xlink
- Certifications
  - IBM Certified Developer: XML - DTDs, analyze documents, create XML structure from data
  - Brainbench - stylesheets, specs, parsing
  - ECertifications - basic concepts, architecture, objects.
  - a word about certifications - get someone else to pay for certs
admin
- clean out your working directories, archive
- book reviews
- book draw
- final roll
- sign certs / assessments
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