Introduction to Google Web Toolkit

Google Web Toolkit Introduction Didier Girard – girard.d@sfeir.com 2008

Content
Demonstrations
Why GWT ?
How does it run ?
GWT features

DEMONSTRATION

Démonstrations

Demonstrations
http://stuff.ongwt.com

GWT, FOR C*O LEVEL…

GWT is MDI compatible *
GWT applications could have windows residing under a single parent window.
*MDI : Multiple Document Interface

GWT is simple
Developing a web application with GWT is as simple as developing a Windows application with VB

GWT cuts costs
Building a GWT application is 5 times faster than building a J2EE application

GWT is offline compatible
A GWT application doesn’t need a server

GWT, better ergonomic http://swissmiss.typepad.com/weblog/2007/11/task-clips.html Web 1.0 GWT

GWT applications are efficient
Local computation, bandwidth optimization

Ajax advantages

Ajax : Partial update of the screen
No more « Blank page » effect

Ajax : Asynchronous updates
Fresh data without reload

Ajax : Rich Widgets
Widgets : One more beautiful than the other

Ajax : Better scalability
Stateless Server
Statefull client
Data Base Data Application GUI+Business + Session

At first, Ajax is really cool
So beautiful
So efficient
Customers love it

But, what about…
… cross-browser
… memory leak
… loading latency
… « Javascript PhD »
… ajax IDE
… bugs (javascript is a dynamic language)
… cross browser javascript debugger
… security
…

The solution – First step
Build the prototype of the application
It is really fun
Everybody will admire you

The solution – Second step
Your customer purchases : leave the project :-)

Choose GWT

GWT, HOW DOES IT RUN ?

GWT manifest
GWT should help to code stable, efficient and cross-browser applications
GWT should be friendly for developers
Compatible with IDE, support debugging, refactoring, strong typing…
The based line : « First the user, second the developer » - Bruce Johnson

The approach
Code in java
Compile the java to Javascript

Hello World
Demonstration

Architecture Browser IE, Firefox, Safari, Opera RWA in Java Java Runtime Library java.lang java.util Java.io GWT GUI Library GWT Compiler Application code Panels Popup Stack Absolute Vertical … Widgets Button MenuBar Radio Tree Check Table TextArea … . Javascript Application GWT Runtime 100Ko

OVERVIEWS

Widgets : « 100% java »
Demonstration (Kitchen Sink)
http://code.google.com/webtoolkit/examples/kitchensink/

History support
« Single Page Interface » with history support !
Demonstration (Kitchen Sink)
Code :
History. addHistoryListener(myCommand);

RPC Support (JSON/XML-RPC)
AJAX is a story of asynchronous request
With GWT, it is simple !

I18N/L10N support
Simple and powerfull

Absolute Panel
Rapid Application Development : sometime, you need it
Absolute panel : a pleasure !
A panel of Panels : Grid, Row, Flex, Vertical, Tab,…

Cross browser, cross platform

CSS
GWT widgets are CSS compatible

Debugger
Demonstration

Javascript integration
JSNI, a clever API
Many javascript library are already wrapped : Dojo, Extjs,…
Demonstration
public static native void alert(String msg) /*-{ $wnd.alert(msg); }-*/;

Optimization
Compiled javascript is optimized
Only the necessary javascript is downloaded by the browser
IE downloads only javascript for IE, Firefox downloads only javascript for Firefox
Unused APIs are removed from the compiled javascript

Good scalability
GWT server could be stateless
No more session affinity

Tools
GWT is supported by all the java IDE : Eclipse, NetBeans, IntelliJ IDEA, JDeveloper,…
Advertisement : my favorite tool is GWT Designer

GWT : THE Community
Millions of download
11000 subscribers to the forum
Books
Tones of Books
Tones of tutorials
Blogs

GWT 1.4, faster, faster, faster
Example : ImageBundle, kind of database for images
From 12 requests to 1 request…
ClippedImage timeIcon = new ClippedImage("icons.png", 22, 0, 22, 22); http://roberthanson.blogspot.com/2007/02/gwt-clippedimage-optimizing-image.html

GWT Gears
Gears helps to build offline application
GWT wrapper :
http://code.google.com/p/gwt-google-apis/
Demo
Google Confidential

GWT : summary
It is 5 times faster to build a GWT application
Refactoring
Debugging
Stateless server
Cross-browsers
I18N
Hosted mode
JSNI

TIPS AND TRICKS

Think differently!
Rethink application ergonomic.
Forget browsing
MDI is possible
Stateless server, statefull client
-> Demo
http://code.google.com/p/gdf
Google Confidential

A language is behind the other
It is not a java application, it is javascript application coded with the java API !
For example, « long » is not a javascript type !
-> Demonstration
Google Confidential

Misc
DOM manipulation is costly
Your user can have : « slow script message »
-> Use « IncrementalCommand » ( DEMO )
No need to send tones of asynchronous request
Deal with RPC error by subclassing AsyncCallback
Forget javascript
Use Selenium ( DEMO )
Use Maven
Google Confidential

COMMONPLACE

You must used java on the server
No, GWT is server free

Compiled javascript is impossible to debug
It is possible to change compilation option
But you never need to it,
-> Demo

GWT Widgets ? Bof….
GWT widgets are basic
It is really easy to build its own widget
Many libraries
GWT Ext
GWT Rialto
Tatami
GWT Widget
GWTaculous
MyGWT
…
Google Confidential

GWT are heavy
Compiled javascript is light and gzippable
KitchenSink is around 60Ko !

GWT is HTML incompatible
Wrong
It is possible to include GWT components in a classical HTML page

GWT are applets
Applets, no thanks :-)
Java is compiled to javascript !

GWT is not free
Noooo
GWT is opensource (Apache licence)

Ressources GWT : http://code.google.com/webtoolkit/ Forum : http://groups.google.com/group/Google-Web-Toolkit GWT Blog : http://googlewebtoolkit.blogspot.com/ onGWT, Tracking news on GWT : http://www.ongwt.com/

SFEIR
6 projects with GWT
5000 days of coding
It is just fun
Clients are very happy with their applications
Our stack : GWT/Spring/Hibernate
Jobs: girard.d@sfeir.com
Google Confidential

Conclusion GWT, c’est facile, efficace et beau ! Merci à l’équipe GWT, Merci à la communauté, Merci à Google !

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Introduction to Google Web Toolkit

by dgirard on Feb 04, 2008

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