GWT introduction. Presented at Oracle Week Israel 2010 by Yoav Aharoni.

1. GWT – The Java Advantage
Yoav Aharoni
Consultant, AlphaCSP

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» Introduction
» GWT in Action
» How does it work?
» Key Features
» Best Practices
» Recap
» Discussion
» 3rd Parties
» Reference
Agenda

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Introduction
GWT What?

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 A Web Framework.
 A SOUI / SOFEA Framework.
 A Sort of JavaScript Framework.
 One of Google’s gifts to Java developers.
 All of the Above.
Google Web Toolkit Is:
Introduction
Service-Oriented Front-End
Architecture or Service-
Oriented User Interface

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» A web framework for rapid developing and debugging
of JavaScript front-end applications in Java.
1. Develop in Java.
2. Compile into JavaScript.
3. Run on a Browser.
GWT in a Nutshell...
Introduction
BrowserJavaScriptJava

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“GWT's mission is to radically improve the web
experience for users by enabling developers to use
existing Java tools to build no-compromise AJAX for
any modern browser.”
Mission Statement
Introduction

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» It’s built for speed and it’s fast as it gets.
» Runs natively on the browser, no plugins needed.
» Cross browser compatible.
» Has everything a framework needs.
 Dynamic, rich, reusable widgets. Lots of them.
 Utilities and more.
» Big active community.
» Many 3rd party libraries already out there.
» Simple built-in Ajax/RPC mechanism.
What’s so good about it?
Introduction

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» Develop using Java.
 Using YOUR IDE.
 Detect error in compile-time rather than runtime.
 Java tools: refactoring, debugging, profiling, etc…
 JUnit integration.
» Good development environment.
» It’s Open source: Apache v2.0 license.
» It’s Google’s – will be around for a long time.
What’s so good about it?
Introduction

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» Announced at JavaOne, 2006.
» Formerly known as “Project Red Pill”.
» Current release: 2.1.
History
Introduction
05/
2006
10/
2010
06/
2009
GWT 1.0 RC 1
08/
2006
11/
2006
02/
2007
08/
2007
08/
2008
04/
2009
12/
2009
V 2.0V 1.7 V 2.1V 1.5

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» Announced at JavaOne, 2006.
» Formerly known as “Project Red Pill”.
» Current release: 2.1.
History
Introduction
05/
2006
10/
2010
06/
2009
GWT 1.0 RC 1
V 2.0V 1.7
08/
2006
11/
2006
02/
2007
08/
2007
08/
2008
04/
2009
12/
2009
V 2.1
• Support for Java 5 features.
• Even more compiler optimizations.
• UI library additions (animations, themes).
• I18N (Bi-di, pluralizations), accessibility.
• Better DOM API.
V 1.5

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» Announced at JavaOne, 2006.
» Formerly known as “Project Red Pill”.
» Current release: 2.1.
History
Introduction
05/
2006
10/
2010
06/
2009
GWT 1.0 RC 1
V 2.0V 1.7
08/
2006
11/
2006
02/
2007
08/
2007
08/
2008
04/
2009
12/
2009
V 2.1
• Development Mode
• Speed Tracer
• Code Splitting
• Compiler Optimizations
• Draft Compile
• Declarative UI
• ClientBundle
• HtmlUnit
V 1.5

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» Announced at JavaOne, 2006.
» Formerly known as “Project Red Pill”.
» Current release: 2.1.
History
Introduction
05/
2006
10/
2010
06/
2009
GWT 1.0 RC 1
V 2.0V 1.7
08/
2006
11/
2006
02/
2007
08/
2007
08/
2008
04/
2009
12/
2009
V 2.1
• Cell Widgets
• MVP Framework
• Request Factory
• Editor framework
• Logging
• SafeHtml
• Spring Integration
V 1.5

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GWT in Action
Seeing is believing

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How does it work?
... and why is it so damn fast...

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Architecture
JRE Emulation
GWT Compiler
Dev.
Mode
Class Library
Development
Servlet Container
GWT RPC
Remote Service Servlet
Web
Services
Server-Side
Ajax
GWT Runtime
Compiled
JavaScript
Client-Side
Compile

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Development Lifecycle
Download SDK
+ Browser Plugin
Create Project
with IDE/Maven
Develop & Code
View & Debug
using Dev. Mode
Compile to
JavaScript
Deploy to Prod
Server
Profile with
Speed Tracer
Unit Test with
Java Tools
Debug using
Dev. Mode
Fix Bugs

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» Definition: a technique used by the GWT compiler to
create and select a specific implementation of a class
based on a set of parameters.
» GWT produces a different application permutations for
each browser environment.
 Only one of these permutations is downloaded and executed
by the browser.
 Permutations can be created for each Locale.
 Additional custom parameters can be configured.
Deferred Binding
DOMImpl impl = GWT.create(DOMImpl.class);

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» Branching is done in compile time rather than runtime.
 No runtime penalty for lookup.
» Download and evaluate only the minimum needed
code.
 Reduce download size.
 Reduce execution time.
» Saves development time by automatically generating
code to implement an interface or create a proxy class.
Deferred Binding - Benefits
More Info

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» Only “used” code is compiled.
» Highly optimized JavaScript and CSS code.
» Images can be combined into one file to minimize
server requests (aka Image Sprites).
Compilation

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» JavaScript implementations of the most commonly
used classes in JRE
 most of the java.lang package
 a subset of the java.util package
» Several classes are missing
 java.util.Calendar
 date-formatting classes
JRE emulation library
More Info

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Developing with GWT
Lets get to work!
More Info

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» Google SDK
» Eclipse
 Google Plugin for Eclipse
 Google GWT Designer (previously Instantiations)
 Cypal Studio for GWT
» IntelliJ IDEA - GWT Support Plugin.
» Netbeans - GWT4NB Plugin
» Maven - gwt-maven-plugin
» Speed Tracer
» GWT Theme Generator
Available Tools
More Info

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Key Features
Tools of the Toolkit

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» Widgets, Panels and Layout
» Ajax
» Internationalization
» ClientBundle
» UiBinder
» JavaScript Native Interface
» Bookmarks & Browser History Management
» Logging
» Safe HTML
» Validations
Key Features

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Best Practices
Learn from experience

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» All around the world developer have embraced:
Google Web Toolkit Best Practice.
» Highlights:
 Embrace Asynchrony.
 Command (dispatcher) pattern.
 Decoupling, decoupling, decoupling.
 MVP (Model/View/Presenter) pattern.
 Dependency Injection.
 Event Bus.
 Support history from the start (using PlaceManager).
GWT Best Practices

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» Many 3rd party libraries implementing these concepts
has spawned.
» In GWT 2.1 built-in support for MVP, activities and
places was added.
 Joining the existing event bus support.
GWT Best Practices

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HTML5 Show Case

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Recap
Let’s wrap it up

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» Driven by a big corporation - Google.
» Lighting fast.
 UI code runs at the client.
 Deferred binding.
 Code optimizations and magnification.
 Code splitting.
 Image Sprites.
 Asynchronous DNA.
 No state needs to be saved on the server.
Pros
Recap
Scalable
Responsive
Application
=

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» Big, active community.
» Mature project (Version 2.1), ever improving.
» Has all you’re ever need + many 3rd party libs.
» Open Source (Apache v2.0) License.
» No Plugins needed.
» HTML 5 support.
» Can work with any back-end technology (like .NET) or
even without any back-end application.
Pros
Recap

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» Satisfying development cycles using development
mode.
» Java development, with all benefits included.
 Java tools, refactoring, debugging.
 Strictly typed.
 Detect errors in compile time.
 Java unit testing.
» Toolkit tools: IDE plugins, Designer.
Pros
Recap

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» Relies entirely on JavaScript.
 Cannot work if JavaScript is disabled.
 Accessibility issues (especially with older readers etc).
 Limited reflection.
 Limited SEO (search engine optimization).
» HTML Markup is harder to tweak.
» Longer design-refresh development cycles compared to
pure HMTL/CSS/JavaScript development.
» Almost impossible to debug production client-side code.
Cons
Recap

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» When using RPC, model passed to the client must be
“hand-picked”.
 i.e when working with JPA/Hibernate.
 Might need to create TOs.
» Relatively slow bootstrap on page load compared to
plain HTML/CSS pages.
 Which is eventually faster, if application only loads once.
 But might be annoying if application is reloaded on every page
change.
Cons
Recap

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» Best for:
 Building RIA.
 Desktop like applications.
 HTML5 Games.
 Gadgets.
» Not to be used for:
 Building simple/content websites.
 Applications which relies heavily on form submit.
Conclusion
Recap

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Discussion
...This is the part where you ask questions...

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3rd Parties
Community Contributions

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» Google Web Toolkit Incubator
» Ajax/REST:
 GWT-REST
 RestyGWT
 Restlet
 Gwittir (+ other utilities)
» Widgets and more:
 Ext GWT (aka GXT), based on Ext-JS
 SmartGWT, based on Smart-Client
 Tatami, based on Dojo
 GWT Mosaic
3rd Party Libraries & Frameworks

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» Patterns (MVP, MVC,...):
 GWT-Presenter
 GWT-Dispatch
 GWT-MVP
 GWTP
 GWT-Pectin
 MVP4G
» Charts:
 Gchart – HTML5/Canvas Charts (no Plugins).
 OFCGWT – Open Flash Chart integration.
 Charts4j-GWT – Google API Charts.
3rd Party Libraries & Frameworks

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» Dependency Injection:
 GIN – Guice-like DI
 GWToolbox – Spring-like DI + utilities + widgets.
 Rocket-GWT – DI + utilities.
» Utilities:
 GWT-Log – Logging.
 GWT-Validation – Validation.
 GWT-DND – Drag n’ drop.
 GWT-FX – Animations.
 Goda-Time – Joda Time for GWT.
 GWT-Mobile-Webkit – HTML 5 support.
3rd Party Libraries & Frameworks

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» Canvas:
 GWT-Canvas
 GWT-G2D
 GWTCanvas – inside Google Incubator.
» Misc:
 Emite – XMPP (Jabber) Chat Client.
 GWT-Cal – Calendar widget (like Google Calendar, Outlook, iCal).
 Vaadin – Framework based on GWT.
 GWT-Client-Storage – HTML5 local storage.
3rd Party Libraries & Frameworks

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» Spring Integration
 Spring MVC
 Spring Roo (since GWT 2.1)
 Spring Insight profiler.
» Vaadin – Framework based on GWT.
Integration

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» GWT Reference
» Javadoc
» Forum
» onGWT.com
» Blog
» Books
Documentation
Reference
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Thank You!
