Wicket is a component-oriented web application framework that allows web development using pure Java and HTML. It offers a clean separation of concerns between HTML and programming logic, facilitating easy manipulation of web pages as Java objects. The framework is open source, configurable in web.xml, and operates in both development and deployment modes, each providing different debugging and performance capabilities.

1. Wicket Programming

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Course Schedule
• Wicket Intro
• Core Concepts
• Components
• Forms and Models
• Validation
• Wicket and Ajax
• Data Components
• jQuery Integration
• New Features
2
• What is Wicket?
• Component Orientation
• Wicket Features
• More Wicket Features
• Wicket Timeline
• Component Hierarchy
• Wicket in Architecture
• Wicket Configuration
• Hello Wicket Application
• Hello Wicket HTML Page
• General Application Structure
• Wicket Run Modes
• Setting Up Wicket
• Wicket Distribution and Modules
• Wicket Resources

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What is Wicket?
• Wicket is a Component Oriented Web Application framework :
• Web Development done with pure Java and pure HTML
• Brings object oriented programming to the view layer :
• Re-applies Model View Controller pattern on components instead of requests
• Follows traditional model for UI development on thick clients :
• Unlike traditional Web Application frameworks like Struts and Spring MVC
• Clean separation of concerns between HTML and Java
• Enables component-oriented, programmatic manipulation of markup
• HTML not polluted with programming semantics :
• Only simple tagging constructs in markup
• Open Source Framework of Apache Software Foundation :
• Enthusiastic developer community
• Name “Wicket” means “gate” and is easy to remember :
• Lightweight door in immovable Java EE gate
3Wicket Intro

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Component Orientation
• Wicket is a Component Oriented Framework :
• Build a model of requested page on the server side
• HTML sent back to the client is generated according to this model
• Model can be thought of as an “inverse” JavaScript DOM :
• Model is built on server-side
• Model is built before HTML is sent to client
• HTML code is generated using this model and not vice versa
• Web pages and HTML input controls are instances :
• Live inside the JVM heap and can be handled like other Java classes
• Approach is similar to how GUI Framework like Swing works
Wicket Intro 4
Client requests
a page
Page model is
created by
framework
Html is generated
according to page
model
Html is returned
to the client

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Wicket Features
• Based on Plain Old Java Objects (POJO‘s) :
• All code written in Java like in Swing GUI with maximum type safety
• Requires minimal configuration :
• Avoids overuse of XML configuration files
• Web Form support with :
• Nested forms and no more double submit of forms
• Offers Ajax functionality "without" JavaScript :
• Fully solves back button problem and has Ajax Debug Window
• Easy to create bookmarkable pages
• Page composition :
• Panels, borders and markup inheritance
• Excellent I18n localization and style support :
• Automatic client capabilities detection and template and resource loading
• Offers fancy components out of the box :
• Data aware tables, date picker, Google Maps tabbed panel, tree, wizard
5Wicket Intro

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More Wicket Features
• Easy to integrate with Java security :
• Offers component level security
• Can integrate with many other frameworks :
• Spring, Guice, Hibernate, JasperReports, OSGi
• Easy creation and use of custom components :
• Reusable components
• URL Handling :
• Safe URLs and Nice URLs (mounting) pretty URLs
• JUnit testing :
• WicketTester Testing support
• And the following as well :
• Out of the Box support for clustering
• State management through type safe sessions
• Extensive logging and error reporting facilities
• Header contribution Javascript and CSS
6Wicket Intro

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Wicket Timeline
• 2004 :
• First Encounter, Jonathan Locke envisioned and originated Wicket
• 2005 :
• Demonstrated at JavaOne 05
• 2007 :
• Adopted at Apache Software Foundation, WUG‘s start spawning
• 2008 :
• Version1.3 released with many improvements
• 2009 :
• Version 1.4 requires Java 5 as the minimum JDK version, generics support
• 2012 :
• Version 1.6 brings jQuery integration, complete control over AJAX requests
• 20015 :
• Version Wicket 7 released
• 20019 :
• Milestone version Wicket 9 released
Wicket Intro 7

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Component Hierarchy
• Wicket :
public class HelloWorld extends WebPage {
public HelloWorld() {
add(new Label("message", "Hello, World!"));
}
}
• Swing :
public class HelloWorld extends JFrame {
public HelloWorld() {
add(new Label("Hello, World!"));
}
}
8Wicket Intro

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Presentation Tier
Business Tier
Integration Tier
Shared
Objects
UserWicket in Architecture

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Wicket Configuration
• Wicket is configured in web.xml :
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
<filter>
<filter-name>HelloWorldWicket</filter-name>
<filter-class>
org.apache.wicket.protocol.http.WicketFilter</filter-class>
<init-param>
<param-name>applicationClassName</param-name>
<param-value>hellowicket.WicketApplication</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>HelloWorldWicket</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
• Filter maps all requests to WicketApplication class
10Wicket Intro

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HelloWicket Application
• Wicket application class loads Wicket WebPage :
public class WicketApplication extends WebApplication {
public Class<? extends WebPage> getHomePage() {
return HelloWicket.class;
}
public void init() {
super.init();
}
}
• Wicket WebPage loads label for GUI :
public class HelloWicket extends WebPage {
public HelloWicket() {
add(new Label("helloMessage", "Hello WicketWorld!"));
}
}
Wicket Intro 11

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HelloWicket HTML Page
<!DOCTYPE html>
<html xmlns:wicket="http://wicket.apache.org">
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<h1 wicket:id="helloMessage"></h1>
</body>
</html>
Wicket Intro 12
<h1 wicket:id="helloMessage"></h1>
+
add(new Label("helloMessage",
"Hello WicketWorld!"));
=
<h1>Hello WicketWorld!</h1>
Demo01
HelloWicket

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General Application Structure
• Markup in HTML files :
• Layout the element hierarchy
• Style the elements
• Code in Java classes :
• Mirror and implement markup's element hierarchy
• Event handling
• Property files with auxiliary role :
• Strings and internationalization
• Logging in e.g. log4j.properties
• Application Configuration :
• In web.xml of Java Web Application
• Application initialization :
• In init method of Application class
13Wicket Intro

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Wicket Run Modes
• Development mode :
• Exceptional error pages, Dynamic markup reloading, No caching
• No JavaScript/CSS Optimizations, Wicker Debugger visible
• Discover mistakes early (serialization, missing components)
• Wicket warns when running in development mode as follows :
********************************************************************
*** WARNING: Wicket is running in DEVELOPMENT mode. ***
********************************************************************
• Deployment mode :
• Cache markup resources, No checks, Don’t display stack traces to users
• Minimize and compress JavaScript, Don’t generate Wicket tags
• Wicket Debugger not visible
• Do not run an application in production using development mode
• Change by setting context parameter in web.xml :
<context-param>
<param-name>configuration</param-name>
<param-value>deployment</param-value>
</context-param>
Wicket Intro 14

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• Download Wicket Binaries Library :
• from http://wicket.apache.org/
• Or
• Use Maven :
<dependency>
<groupid>org.apache.wicket</groupid>
<artifactid>wicket-core</artifactid>
<version>${wicket.version*}</version>
</dependency>
Wicket Intro 15
Setting Up Wicket

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Wicket in IDE’s
• NetBeans includes Maven support :
• Start directly by just opening the folder containing our project
• Intellj IDEA comes with a Maven importing functionality :
• Started under “File/New Project/Import from external model/Maven”
• Next just select pom.xml file of our project
• Eclipse import procedure :
• Select import maven project and point to pom.xml file
• Classpath variable MAVEN_HOME should point to local Maven repository
Wicket Intro 16

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Wicket Distribution and Modules
Module name Description
wicket-core Contains the main classes of the framework, like class Component and Application
wicket-request This module contains the classes involved into web request processing.
wicket-util Contains general-purpose utility classes for functional areas such as I/O, lang, string
manipulation, security, etc...
wicket-datetime Contains special purpose components designed to work with date and time
wicket-bean-validation Provides support for JSR 303 standard validation
wicket-devutils Contains utility classes and components to help developers with tasks such as
debugging, class inspection and so on
wicket-extensions Contains a vast set of built-in components to build a rich UI for our web application (Ajax
support is part of this module)
wicket-auth-roles Provides support for role-based authorization
wicket-ioc This module provides common classes to support Inversion Of Control. It's used by both
Spring and Guice integration module
wicket-guice Provides integration with the dependency injection framework developed by Google
wicket-spring This module provides integration with Spring framework
wicket-velocity Provides panels and utility class to integrate Wicket with Velocity template engine
wicket-jmx Provides panels and utility class to integrate Wicket with Java Management Extensions
wicket-objectsizeof-agent Provides integration with Java agent libraries and instrumentation tools
Wicket Intro 17

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Wicket Resources
• Homepage : http://wicket.apache.org
• Documentation : https://code.google.com/p/wicket-guide
• Wiki : https://cwiki.apache.org/WICKET
• Source code : https://github.com/apache/wicket
• Demo site : http://www.wicket-library.com
• Official user list : users@wicket.apache.org
• Official development list : dev@wicket.apache.org
• Official forum : http://apache-wicket.1842946.n4.nabble.com
• Official IRC channel : irc.freenode.net ##wicket channel
• Users FAQ : http://cwiki.apache.org/WICKET/faqs.html
• Why Wicket? article at http://wicket.apache.org/meet/introduction
• Confluence : https://cwiki.apache.org/confluence/display/WICKET/
• Twitter accounts of :
• Jonathan Locke, Igor Vaynberg, Martijn Dashorst, Eelco Hillenius
18Wicket Intro

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Summary : Wicket Intro
• Wicket is a Component Oriented Web Application framework :
• Web Development done with pure Java and pure HTML
• Open Source Framework of Apache Software Foundation :
• Enthusiastic developer community
• Wickets place in architecture :
• Situated in presentation tier of application
• HTML not polluted with programming semantics :
• Only simple tagging constructs in markup
• In Wicket Web pages and HTML input controls are instances :
• Live inside the JVM heap and can be handled like other Java classes
• Wicket is configured in web.xml :
• Filter maps all requests to WicketApplication class
• Wicket application can execute in two modes :
• Development mode and deployment mode
• Development mode gives a lot more debug information
Wicket Intro 19
Exercise 01
Getting Started