XHTML, XForms, XML Events

1
XHTML, XForms, XML Events Device Independence

• Based on W3C Specs as of April 2002
• Marc Abrams
• Abrams_at_vt.edu

2
XHTML Overview

• XHTML 1 Put HTML4.01 into XML syntax
• XHTML 1.1 Modularize XHTML for resource
  constrained devices
• DOM-2 support Attach event handlers to XHTML
  elements via XML Events

3
XForms Goals

• Provide richer Web forms
• Multiple forms per page, and pages per form
• Provide form processing model
• Forms Submit Protocol
• Suspend and Resume support
• Provide forms on various devices
• Seamless integration with other XML tag
  sets(XHTML, WML, )
• Relies on XML model of form data(vs. HTMLs
  simple namevalue pairs)
• XForms Model to describe structure of XML
  Instance Data
• Separate data, logic and presentation

4
Relation of XForms Components
Diagram from W3C http//www.w3.org/MarkUp/Forms/
arch1.png
5
Usage Scenario Underlying XForms

• Web designer starts with a purpose (e.g., data
  collection)
• Purpose is realized by interactive presentation
  (a form)
• Completion of form produces data
• ExamplePurpose find students in a
  coursePresentation form with list of course
  sData chosen course number

6
Old style HTML Form

• ltform action"http//example.com/submit"
  method"post"gt
• ltlabelgt
• ltinput type"radio" name"as"
  value"cash"/gt Cash
• lt/labelgt
• lt/formgt

7
XForms Example (1)

• ltxformsmodelgt
• ltxformssubmitInfo action"http//examples.com/
  submit" id"submit"/gt
• lt/xformsmodelgt

8
XForms Example (2)

• ltinput ref"cc"gt
• ltcaptiongtCredit Card Numberlt/captiongt
• lt/inputgt
• ltsubmit submitInfo"submit"gt
• ltcaptiongtSubmitlt/captiongt
• lt/submitgt

9
Data Submitted by Browser

• Hey, its XML, not that weird http//?x123!
• ltinstanceDatagt
• ltasgtCreditlt/asgt
• ltccgt1235467789012345lt/ccgt
• lt/instanceDatagt

10
Instance Data Is Described by Model

• ltxformsmodelgt
• ltxformsinstancegt
• ltpayment as"credit" xmlns"http//commerce.ex
  ample.com/payment"gt
• ltcc/gt
• lt/paymentgt
• lt/xformsinstancegt
• ltxformssubmitInfo action"http//example.com/su
  bmit" method"post"/gt
• lt/xformsmodelgt

11
XML Events

• Motivation
• HTML does this
• ltimg onMouseOver document.images.button1.src'c
  lick.gifgt
• Problems
• Must change HTML to add new event names
• Mixes event handling into document content

12
XML Events - Example

• lta id"link1" href"doc.html"gtThe ltemgtdraftlt/emgt
  documentlt/agt
• ltlistener event"click" observer"para1"
  target"link1" handler"clicker"/gt
• You can attach listeners to any XML tree node.

13
Conclusion

• XHTML is modular, but not truly device
  independent
• XForms is device independent, but only provides a
  form metaphor
• They are limited to XML languages (not Java, C)
• So these are steps toward general device
  independence, but not a full solution

14
References

• XML Events(http//www.w3.org/TR/2001/WD-xml-event
  s-20011026/)
• XForms - The Next Generation of Web Forms
  (http//www.w3.org/MarkUp/Forms/)
• XHTML Roadmap(http//www.w3.org/MarkUp/xhtml-road
  map/)