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Ajax Presentation for the TSSG


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A presentation I did to the TSSG on Ajax (

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Ajax Presentation for the TSSG

  1. 1. Ajax TSSG Tech Session by Paul Watson (
  2. 2. Ajax is not… <ul><li>A soccer football team (go Barcelona!) </li></ul><ul><li>Or a cleaning agent </li></ul>
  3. 3. Ajax is… <ul><li>Asynchronous JavaScript + XML </li></ul><ul><li>A term coined by Jesse James Garret of Adaptive Path </li></ul>Not Jesse James the outlaw
  4. 4. But <ul><li>Forget what the term stands for </li></ul>
  5. 5. Ajax Enables rich user interfaces
  6. 11. Ajax Web-sites become Web-clients
  7. 12. Before Ajax
  8. 13. Before Ajax <ul><li>One page per request </li></ul><ul><li>One URL for one page </li></ul><ul><li>The whole page updates </li></ul>
  9. 14. With Ajax
  10. 15. With Ajax <ul><li>Each action has a URL </li></ul><ul><li>Multiple requests per page </li></ul><ul><li>You control what updates </li></ul>
  11. 16. Each action has a URL <ul><li>Your web-server becomes a data provider </li></ul><ul><li>It sends snippets of text (XML, HTML, JSON etc.) </li></ul><ul><li>The client processes the data </li></ul>
  12. 17. XML <ul><li>Forget about it </li></ul><ul><li>JavaScript + XML is painful </li></ul><ul><li>XHR handles text </li></ul><ul><li>Use JSON </li></ul><ul><li>Don’t use HTML fragments </li></ul>
  13. 18. XmlHttpRequest <ul><li>The key </li></ul><ul><li>Fire off HTTP requests without refreshing the browser </li></ul><ul><li>Microsoft invented it </li></ul><ul><li>In most browsers (IE, Firefox, Opera, Safari) </li></ul><ul><li>XHR is easier to say </li></ul>
  14. 19. XmlHttpRequest
  15. 20. Not for everything <ul><li>Use Ajax wisely </li></ul><ul><li>Three paths </li></ul><ul><ul><li>Standard web-site </li></ul></ul><ul><ul><li>Ajax enhanced web-site </li></ul></ul><ul><ul><li>Ajax web-client </li></ul></ul>
  16. 21. Challenges <ul><li>Chatty clients –request caching & batching </li></ul><ul><li>Cross-browser – abstracted by libraries </li></ul><ul><li>Back and forward – not easy </li></ul><ul><li>Security – same as ever </li></ul><ul><li>Network issues – client exception handling </li></ul><ul><li>Browser bottleneck – batching & caching </li></ul><ul><li>User feedback – visual cues </li></ul><ul><li>Multiple actions – request prioritisation </li></ul><ul><li>Accessibility – not easy </li></ul>
  17. 22. Tools <ul><li>Few tools </li></ul><ul><ul><li>Notepad </li></ul></ul><ul><ul><li>Firefox </li></ul></ul><ul><ul><li>FireBug </li></ul></ul><ul><li>Many libraries </li></ul><ul><ul><li>Prototype, Atlas, Anthem, Dojo etc. </li></ul></ul>
  18. 23. Testing <ul><li>Same testing tools you use for your current web-sites </li></ul>
  19. 24. + Ajax