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By Eyal Golan – Senior Java Consultant @ Tikal Knowledge

Introduction to

Copyright 2007 Tikal Knowledge, Ltd. | 2 |

“Apache Wicket is a component oriented Java web application framework. With proper mark-up/logic separation, a POJO data model, and a refreshing lack of XML, Apache Wicket makes developing web-apps simple and enjoyable again. Swap the boilerplate, complex debugging and brittle code for powerful, reusable components written with plain Java and HTML.*”

*The Wicket Team


Introduction to Wicket - Agenda

What is Wicket?» Wicket in a Nutshell

» Stateful, Just Java, Just HTML

Wicket Architecture The component concept Getting Wicket Wicket’s Features Wicket on the web Q&A


Wicket in a Nutshell

“A Java software framework to enable component oriented, programmatic manipulation of markup.” (WIA)» Manipulation of markup – Use Wicket to manipulate the

markup tags and their contents. (<span>[content]</span>)

» Programmatic manipulation – Wicket forces a strict separation of presentation and logic. Java is used to derive the dynamic parts of the markup templates.

» Component Oriented – The application is constructed of reusable components. The components have their own states and behaviors. It is very similar to programming with Swing / SWT.


Wicket is stateful

Wicket is a stateful framework.» Wicket was developed to solve the problems that REST introduced to

web applications development• Security, modularization, state maintenance and everything as Strings

» No need to decide how to pass state• Wicket manages state transparently

» Wicket hides the fact that you work on a stateless protocol• Feels like regular Java programming

The state of components is managed for you.» public class EditBarLink extends Link {

private final Person person; public EditBarLink(String id, Person person) { super(id); this.person = person; } public void onClick() { setResponsePage(new EditPersonPage(person)); } }


Just Java

You decide how components are created, assembled and combined and - to some extend – what their life cycle looks like» The developer is in charge of how the components are

created• Constructor, inheritance etc.

» Component classes can be designed in any way• Class members, hierarchy etc.


Just HTML

Just HTML» Presentation is defined in HTML markups

» HTML templates you use with Wicket only contain static presentation code (markup) and placeholders where Java components are hooked in

• There is never logic in the templates

» You pretty much have to know the structure of your page* upfront

• * Or any other component that has a corresponding markup (Page, Panel, Border and Fragment). This will be explained later

• * The pieces can be put together dynamically

» <tr>

<td wicket:id=”list”>

<span wicket:id=”name” />

</td>

</tr>

Dynamic Table



What is Wicket? Wicket Architecture / behind the scene

» A brief explanation

The component concept Getting Wicket Wicket’s Features Wicket on the web Q&A


Wicket Architecture

In this section we will go over the main role players of a Wicket application» This is only a brief introduction

» The section is intended only to be familiarized with the primary classes that create a Wicket application

Application» One object instance for an application

» Bundles all components, markups, properties, settings files etc.

» Acts as the central hub of processing

» The Application object is used for customize the application’s behavior

Session» Holds the state of one user

» Wicket allows to have custom session

» With a custom session we know exactly what can be store in a session


Wicket Architecture (cont.)

RequestCycle» Responsible of processing requests

» Uses Request and Response objects

Some examples of Application Customization» A SecuredSession that allows only logged in user to open a certain

page

» How to render a disabled link

» How to mount pages with a nice readable URL

Component» Page, Form, Label, TextField, DropDown, WebMarkupContainer and

much more

Model» The Model is an indirection for how to get the data that drives the

Java components. Models hide ‘what’ data to get and ‘from where’ to get it, and Java components hide ‘when’ and ‘how’ that data is displayed



What is Wicket? Wicket Architecture The component concept

» Hello World… The shortest example ever!

» Component – The building block• A few examples

Getting Wicket Wicket’s Features Wicket on the web Q&A


Hello World – The Short Example

add(new Label("message", "Hello World!"));

Put it in your Java



<h1 wicket:id=“message”>[text goes here]</h1>


+

Add it to your HTML

Put it in your Java



<h1 wicket:id=“message”>[text goes here]</h1>


<h1>Hello World!</h1>

+

=Add it to your

HTML

Put it in your Java

Et Voila


What about picking a date?

DateTextField dateTxt = new DateTextField("dateTxt");dateTxt.add(new DatePicker());add(dateTxt);

<input wicket:id=“dateTxt”></input>

You can manipulate the header by adding calls to CSS and JS files.



What is Wicket? Wicket Architecture The component concept

» Hello World… The shortest example ever!

» Component – The building block

Getting Wicket Wicket’s Features Wicket on the web Q&A


About Components

“Apache Wicket is a component oriented …”» Components are the building blocks of Wicket

They are self contained and do not leak scope» Other components don’t have to know about it

They are reusable You build them using plain Java

» You use them using plain Java

Components can be nested to “components tree”» Each component that is added in the Java file must be added in

the same hierarchy in the corresponding HTML file

» Pages are special components that function as the root for such trees

The components are the objects that encapsulate the manipulation the markup

Their data is separated using the IModel interface


Components Tree Hierarchy


Component + Markup

Component has wicket id Markup has the same wicket:id Hierarchy must much

HTML Code

Java Code

Link link = new Link(“link”) {…}add(link);link.add(new Label("message", “My Message"));

<a href=”#” wicket:id=“link”> <span wicket:id=“message”>[text replaced]</span></a>


Component + Markup

Some components have a markup file associated with them and others don’t

Components with an associated markup» Page, Panel, Border, Fragment

» Both files should reside in the same package folder*, and should have the same name

• src/com/tikal/presentation/HelloWorldPage.java

• src/com/tikal/presentation/HelloWorldPage.html

• *And naturally Wicket allows to configure this behavior

Some components without an associated markup» The markup for this components are located in their parent

XXX.html

» Label, Button, DropDown, Link, Form and more


Component – Link Example

Link link = new Link("link") { … @Override public void onClick() { setResponsePage(OrdersReportsPage.class); } });

<a href=”#” wicket:id=“link”>Click</a>

HTML Code

Java Code


Component – AjaxLink Example

someComponent.setOutputMarkupId(true);AjaxLink link = new AjaxLink("link") { private static final long serialVersionUID = 1L; @Override public void onClick(AjaxRequestTarget target) { // Do Something target.addComponent(someComponent); target.appendJavaScript(“Effects.fade(‘foo’)”); } });

<a href=”#” wicket:id=“link”>Click</a>

The same as regular Link

Some Ajax stuff in Java


Just Java + Just HTML (returned)

The designer creates the page with his favorite designing tool

The Wicket programmer adds wicket:id as a hook in the file

Minor issue – If the HTML hierarchy changes, it should be changed in the Java code as well



What is Wicket? Wicket Architecture The component concept Getting Wicket (So easy…)

» Starting point for Wicket

Wicket’s Features Wicket on the web Q&A


A great quick start in Wicket’s site» http://wicket.apache.org/quickstart.html

» Create a maven archetype to work with

» Run• mvn jetty:run

• Use the Start.java class that is created automatically

• Create a war file and put in a web server (or an application server)

A quick start project that builds your own Wicket project» http://www.antwerkz.com/qwicket/app/home

• A bit tricky to start with it

Wiki getting started» http://cwiki.apache.org/WICKET/newuserguide.html

Getting Wicket



What is Wicket? Wicket Architecture The component concept Getting Wicket Wicket’s Features

» A list of (most) features

Wicket on the web Q&A


Wicket’s Features – The Short List

Automatic State (no HttpSession) POJO for logic

» Reusability

No XML, no configuration files Like Swing Simplicity Active community


Wicket’s Features – The Long List

Clean / clear separation of presentation and logic POJO for logic No XML, no configuration files Security i18n Built-in Ajax without the need to write JavaScript Transparent state and session management

» Stateful» Navigation history, support of multiple tabs/windows in the

browser Markup inheritance (OOD) Has validation Integrating with other frameworks (Spring, Hibernate) Has Lazy Loading facilities Active community



What is Wicket? Wicket Architecture The component concept Getting Wicket Wicket’s Features Wicket on the web

» Some useful links

Q&A


Wicket on the Web

Home of Wicket» http://wicket.apache.org/index.html

Wicket-extension (expansion of Wicket)» http://wicket.apache.org/docs/wicket-1.3.2/wicket-extensions/index.h

tml Wicket Forums

» http://www.nabble.com/Apache-Wicket-f13974.html Wicketstuff (cool libraries for Wicket)

» http://wicketstuff.org/confluence/display/STUFFWEB/Home» http://wicketstuff.org/wicket13/ (examples)

InMethod (Wicket table component)» http://inmethod.com/

Wicket Blogs» http://www.google.com/ig/add?feedurl=http%3A%2F

%2Fpipes.yahoo.com%2Fpipes%2Fpipe.run%3F_id%3Dff2c46188493fc387b9b29d93ff77078%26_render%3Drss

Wicket W. Warrick» http://en.wikipedia.org/wiki/Wicket_W._Warrick


Wicket on the Books

Wicket In Action» Martijn Dashorst, Eelco Hillenius

» http://wicketinaction.com/

» http://manning.com/dashorst/

Pro Wicket» Karthik Gurumurthy

» http://www.apress.com/book/view/1590597222

Enjoying Web Development with Wicket» Kent Tong

» http://www.agileskills2.org/EWDW/


Summary

Wicket is cool and fun Wicket gives an easy and fast Web Application

development Has a very clear OOD approach Lets the user concentrate on the business logic The community is very dynamic and helpful Wicket is a dynamic framework that is built upon users’

request and suggestion» Last Stable version 1.3.4

» Wicket 1.4-M3 is the next version to go out


Q&A


Thank You

[email protected]

[email protected]

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