Does Ajax suck

1
Does Ajax suck?

• CS575 Spring 2007
• Chanwit Suebsureekul

2
Web History

• Static content
• Dynamic content
• Web application

3
Why Web Application?

• Easy application deployment
• Easy application distribution
• No software to download
• No installation
• No update
• Can be used from anywhere

4
Interactivity Issue

• Simple request-response model
• Not so responsive
• Send request, wait for response
• Full page refresh
• Ajax comes to rescue

5
Whats Ajax?

• Asynchronous JavaScript and XML
• A development technique for creating interactive
  web applications
• Makes web pages feel more responsive
• Exchanges data with the server behind the scenes
• Partial page update

6
Ajax

• A combination of technologies
• XHTML and CSS page presentation
• DOM dynamic display and interaction
• XML data interchange and manipulation
• XMLHttpRequest asynchronous data retrieval
• A JavaScript object
• Send HTTP request
• Parse XML response
• Response can be handled asynchronously with a
  callback function
• JavaScript binding everything together

7
Web Application Model
8
Ajax Examples

• Ajax use
• Instant save
• Translating services
• Smart shopping carts
• Form validation (server side VS client side)
• Etc.
• Web application
• Gmail
• Google Maps
• Google Docs Spreadsheets
• Etc.

9
Why Ajax Sucks (Most of the Time)

• http//www.usabilityviews.com/ajaxsucks.html
• The fundamental design of the Web is based on
  having the page as the atomic unit of
  information.
• The page
• the users view of the information on the screen
• the unit of navigation
• can be retrieved using the URL
• Ajax breaks the concept of the page

10
Why Ajax Sucks (contd)

• Breaks the BACK button
• The second-most used navigation feature
• Users can always get back to the firm ground
• Breaking the BACK button is no less than a
  usability catastrophe
• Requires Ajax-compatible browsers
• W3C browser usage statistics
• Print problems

11
Why Ajax Sucks (contd)

• Authoring problems
• HTML is easy
• Ajax is hard to learn that many page authors
  write buggy code
• Search problems
• Web spiders will only search for HREF, SRC, or
  some link tags
• They wont follow Ajax JavaScript code
• Related to the URL problem

12
Ajax Mistakes

• Using Ajax for the sake of Ajax
• Breaking the back button
• Not giving immediate visual cues for clicking
  widgets
• Leaving offline people behind
• Dont make me wait for Ajax

13
Ajax Mistakes (contd)

• Assuming AJAX development is single platform
  development
• Too much code makes the browser slow
• Not having a plan for those who do not enable or
  have JavaScript
• Changing parts of the page unexpectedly

14
Ajax Mistakes (contd)

• Not using links I can pass to friends or bookmark
• Not cascading local changes to other parts of the
  page
• Scrolling the page and making me lose my place
• Blocking Spidering

15
Why Ajax does NOT suck!

• Web application VS Website
• Web application a program made using web
  technology
• Website a bunch of pages linked together
• Ajax is intended and most useful for web
  application, not website
• Dont blame the technology used but the person
  who uses it

16
XMLHttpRequest Usability Guidelines

• Do not load entire pages
• Know the difference between a web application and
  a website
• Do not break what the user is focusing on
• Consider how to handle users that cannot see
  XMLHttpRequest
• Do use it to eliminate confirmation pages
• Do not over-use it