Building Ajax apps with the Google Web Toolkit
- 1. Building Ajax Applications with the Google Web Toolkit Vivek Prahlad
- 2. Agenda What isthe Google Web Toolkit? Features Architectural issues with AJAX applications And how the GWT handles them Experience report: What went well? Gotchas Lots of demos
- 3. What is theGWT? A UI framework for building Ajax apps in Java Best suited for one page Ajax apps Can be embedded into existing apps as well Open Source (Apache 2 license) Component based programming model Similar to, but simpler than Swing / SWT Control application appearance via CSS Simple RPC framework
- 4. Source: Adaptive PathHow are Ajax apps different?
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- 8. Developing applications Clientside code: Java + GWT UI library Restriction: subset of the JDK – java.lang, java.util Compiled to javascript. Morfik, Script# are similar Server side code: GWT RPC + usual suspects Spring & Hibernate Can send domain layer classes over the wire Need to implement IsSerializable Compiled to bytecode as usual
- 9. Features Component basedframework Browser support: IE6+, Firefox, Mozilla, Safari, Opera No Konqueror support Internationalization Debugging Browser history management Integrate with javascript libraries via JSNI JUnit integration
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- 11. Architectural Issues? Backbutton support? Handled by the browser Session state? All on the client, not a server issue UI event handling? All on the client, no round trip Deployment? Compiled Javascript code, java on server side
- 12. Answers to afew Ajax headaches History? Handled by the History class Cross browser support? Abstract DOM class RPC? Java based RPC mechanism
- 13. Building Widgets Buildnew widgets from existing ones Style with CSS No, your app doesn't have to look like Gmail! Layout with panels
- 14. Testing Sahi (http://sahi.co.in ) for functional testing Unit testing via the GWTTestCase Same restrictions as with UI code MVC is your friend Use GWTTestcase for the view Test the Model and Controller as usual
- 15. What went well?Truly cross-browser App needed 2 lines of custom javascript For disabling text selection Great component model Easy to build custom components from scratch Java to Javascript compiler works like a charm No memory leaks Break up large apps with modules & IFrames
- 16. Gotchas RPC mechanismworks only with GWT clients Some widgets use HTML tables internally CSS for layout faster, but more challenging Table widget support weak No MVC separation
- 17. Gotchas Need tobe careful about client side state Ajax apps usually long lived – memory leaks can kill you Some widgets need a lot of custom HTML Tree widget biggest offender Need to replace hibernated objects before serializing Replace PersistentSet, PersistentList with HashSet, ArrayList
- 18. Resources http://code.google.com/webtoolkit http://groups.google.com/Google-Web-Toolkithttp://www.adaptivepath.com/publications/essays/archives/000385.php
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