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AJAX: Web Programming's Toy

AJAX: Web Programming's Toy. Fawaz Ghali F.Ghali@Warwick.ac.uk. Overview. Why AJAX Getting started AJAX Frameworks Demo. AJAX. Asynchronous JavaScript and XML JavaScript communicates with the server (XMLHttpRequest) Asynchronous data transfer

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AJAX: Web Programming's Toy

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  1. AJAX: Web Programming's Toy Fawaz Ghali F.Ghali@Warwick.ac.uk

  2. Overview • Why AJAX • Getting started • AJAX Frameworks • Demo

  3. AJAX • Asynchronous JavaScript and XML • JavaScript communicates with the server (XMLHttpRequest) • Asynchronous data transfer • Web applications are smaller, faster and more user-friendly. • Usually, you still need server programming language (i.e., PHP)

  4. AJAX components • HTML/CSS: presenting information • Document Object Model (DOM): dynamic interaction with the information • XMLHttpRequest object: retrieving data from the server asynchronously • JavaScript: wrap AJAX code

  5. AJAX use • Forms validations • Auto-complete / Auto-suggest • Master-detail relations (more information to display) • User-friendly screens • Web 2.0 applications

  6. How does AJAX work? Source: http://java.sun.com/javaee/javaserverfaces/ajax/tutorial.jsp

  7. AJAX basic example <html>   <head>   <script src="prototype.js" type="text/javascript"></script>   <script type="text/javascript">   function ajaxUpdater(id,url) {    new Ajax.Updater(id,url,{asynchronous:true});   }   </script>   </head>   prototype.js is AJAX library : http://www.prototypejs.org/

  8. AJAX basic example cont HTML code: <body>   <div id="updateme"></div>   <input type="button" value="Update" onClick="ajaxUpdater('updateme',‘hello.php')">   </body>   </html>  

  9. AJAX basic example Cont hello.php: <?php echo "Hello world!";   // you can define any function ?> http://prolearn.dcs.warwick.ac.uk/AH-RO-2008/ajax_demos/ajax_1.html

  10. AJAX Frameworks • AJAX frameworks simplify the code and speed the development. • Depend on server programming language • Component (widgets) use vs. direct use • Mashups with Google, Yahoo!, Flickr etc…

  11. How to choose framework? • Server independent or not? • Structural JavaScript? • Re-usability of your AJAX code? • Documentation (examples, support) • Learning curve

  12. Google Web Toolkit (GWT) • Faster AJAX than you can write by hand • Smaller, more compact, cacheable code • Support IE, Firefox, Mozilla, Safari • Browser's "back" button correctly use • Full-featured debugging • Unit tests (based on JUnit)

  13. GWT <html> <head> <title>Hello</title> </head> <body> <script language="javascript" src="com.google.gwt.sample.hello.Hello.nocache.js"></script> </body> </html>

  14. GWT public class Hello implements EntryPoint { public void onModuleLoad() { Button b = new Button("Click me", new ClickListener() { public void onClick(Widget sender) { Window.alert("Hello, AJAX"); } }); RootPanel.get().add(b); } }

  15. GWT • Demo: http://gwt.google.com/samples/Hello/Hello.html

  16. AJAX Examples & Tutorials • http://www.w3schools.com/Ajax/ • http://www.ajaxtutorial.net/ • http://www.tizag.com/ajaxTutorial/ • http://java.sun.com/javaee/javaserverfaces/ajax/tutorial.jsp

  17. AJAX best practices • Tell the user that the websites uses AJAX (i.e., dynamic update) • Provide non-AJAX options • Provide alerts for dynamic changes • Make navigation easy • Update HTML elements with new content rather creating new elements

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