Apache Wicket

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Apache Wicket

• Gerolf Seitz

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Web Development withjust Java

• and a little bit of HTML

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Gerolf Seitz

• Since Sept.07
• Committer
• PMC
• MSc student (almost finished)
• Software Engineer at Software Competence Center
  Hagenberg GmbH, Upper Austria

4
Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• Summary
• QA

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Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• Summary
• QA

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Wicket in a Nutshell

• Open Source
• Component oriented
• Web application framework
• Java HTML

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Features

• Everything in Java
• State management
• Safe URLs
• Nice URLs (mounting)
• OOTB support for
• Clustering
• Portlet

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Features

• Reusable components
• Nested forms
• No more double submit of forms
• Back-button-support
• I18n
• WicketTester

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Features

• Ajax "without" JavaScript
• Header Contributions
• JavaScript CSS
• Component level security

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Hello, World!

• lth1 wicketid"msg"gttext goes herelt/h1gt

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Hello, World!

• lth1 wicketid"msg"gttext goes herelt/h1gt
• add(new Label("msg", "Hello, World!"))

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Hello, World!

• lth1 wicketid"msg"gttext goes herelt/h1gt
• add(new Label("msg", "Hello, World!"))
• lth1gtHello, World!lt/h1gt

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Hello, World!

• lth1 wicketid"msg"gttext goes herelt/h1gt
• add(new Label("msg", "Hello, World!"))
• lth1gtHello, World!lt/h1gt

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Hello, World!

• lth1 wicketid"msg"gttext goes herelt/h1gt
• add(new Label("msg", "Hello, World!"))
• lth1gtHello, World!lt/h1gt

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Brief History

• 2004 The First Encounter
• 2005 JavaOne'05 Smackdown
• 2006 Incubation at ASF

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Brief History

• 2007 Graduation
• 2007 1.3 released
• 2007 WUGs start spawning Amsterdam meetup 80
  attendees

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Projects

• core
• extensions
• ioc (spring, guice)
• date/time
• velocity
• jmx

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Getting Wicket

• Current Release 1.3.3
• ltdependency
• groupId"org.apache.wicket"
• artifactId"wicket"
• version"1.3.3"
• /gt

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Getting Wicket - Quickstart
http//wicket.apache.org/quickstart.html
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Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• Summary
• QA

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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Application

• Main entry point
• Initialization
• Configuration
• Factories
• Homepage
• Configured in web.xml

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Application

• ltfiltergt
• ltfilter-namegtwicketlt/servlet-namegt
• ltfilter-classgt org.apache.wicket.protocol.http.
  WicketFilter
• lt/filter-classgt
• ltinit-paramgt
• ltparam-namegtapplicationClassNamelt/param-namegt
• ltparam-valuegtexample.MyApplicationlt/param-value
  gt
• lt/init-paramgt
• ltload-on-startupgt1lt/load-on-startupgt
• lt/filtergt

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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Session

• Abstraction of a user session
• Stores session specific data
• Strongly typed session attributes

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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RequestCycle

• Stateful
• Tied to specific user session
• Not (typically) bookmarkable
• Stateless
• Not necessarily tied to specific user session
• Bookmarkable

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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Components

• Basic building blocks
• Encapsulate the programmatic manipulation of
  markup
• Render content
• Receive events
• onClick, onSubmit

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Components lots of em

• Label, MultiLineLabel, TextField,
  PasswordTextField, Image, Link, AjaxLink,
  AjaxFallbackLink, Button, AjaxButton, DatePicker,
  ListView, RefreshingView, DataGrid, DataTable,
  Tree, GMap, Wizard, JasperReports, ...

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Components

• Component has wicketid
• Same wicketid in markup
• Hierarchy must match
• lth1 wicketidmsggtgets replacedlt/h1gt
• new Label(msg, Hello World!)

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Component Link

• lta href"" wicketid"link"gtClicklt/agt
• Link link new Link("link")
• add(link)

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Component Link

• lta href"" wicketid"link"gtClicklt/agt
• Link link new Link("link")
• _at_Override public void onClick()
• //do something
• setResponsePage(new NewPage())
• add(link)

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Component AjaxLink

• lta wicketid"link"gtClicklt/agt
• AjaxLink link new AjaxLink("link")
• public void onClick(AjaxRequestTarget t)
• //do something
• add(link)

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Component AjaxLink

• lta wicketid"link"gtClicklt/agt
• someComponent.setOutputMarkupId(true)
• AjaxLink link new AjaxLink("link")
• public void onClick(AjaxRequestTarget t)
• //do something
• t.addComponent(someComponent)
• t.appendJavascript("Effects.fade('foo')")
• add(link)

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Components

• Components with own markup
• Page, Panel, Border
• Java and markup files in same package on classpath

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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Behaviors

• Plugins for components
• Change attributes of your components markup
• Add Javascript events
• Add Ajax behavior
• timeLabel.add(
• new AjaxSelfUpdatingTimerBehavior(
• Duration.seconds(5)))

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Behaviors

• link.add(new AbstractBehavior()
• public void onComponentTag(Component component,
  ComponentTag tag)
• tag.put("onclick",
• "return confirm('Are you sure?')")
• )
• Output
• lta href"..." onclick"return confirm('...')"gt...
  lt/agt

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Core Concepts

• Application
• Session
• RequestCycle
• Components
• Behaviors
• Models

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Models

• Bind POJO's to Wicket components

new Label("name", model)
ltltPersongt name String city String
Model
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Models

• Lazy binding in Java sucks
• Doesn't update
• new Label("name", person.getName())
• Null checks necessary
• new Label("street", person.getAddress().getStreet
  ())
• Solution OGNL/EL like expressions

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Models

• PropertyModel
• new PropertyModel(person, name)
• new PropertyModel(person, address.street)
• CompoundPropertyModel
• setModel(new CompoundPropertyModel(p))
• add(new Label("name"))
• add(new Label("address.street"))

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Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• Summary
• QA

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Custom Components

• Eelco Hillenius
•  Imagine being told that you can use Java as
  your programming language, but at the same time
  being told not to create your own classes. ...
• I fail to understand why that has to be
  different for UI development, and Wicket proves
  it doesn't have to be so. 

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PasswordStrenghIndicator
lthtmlgt ltheadgt lttitlegtInsert title
herelt/titlegt ltwicketheadgt ltwicketlinkgt
ltlink rel"stylesheet" type"text/css"
href"res/PasswordField.css"/gt lt/wicketlinkgt
lt/wicketheadgt lt/headgt ltbodygt ltwicketpanelgt
ltinput wicketid"password" type"password"
/gtltspan wicketid"strength"gtstrengthbarlt/spangt
lt/wicketpanelgt ltdivgt lthr/gt Examplesltbr
/gt ltinput type"password" /gt ltspan
class"weak"gtnbsplt/spangt (weak)ltbr/gt ltinput
type"password" /gt ltspan class"medium"gtnbsplt/sp
angt (medium)ltbr/gt ltinput type"password" /gt
ltspan class"strong"gtnbsplt/spangt
(strong)ltbr/gt lt/divgt lt/bodygt lt/htmlgt
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PSI - Markup

• ltwicketheadgt
• ltwicketlinkgt
• ltlink rel"stylesheet" type"text/css"
  href"res/PasswordField.css"/gt
• lt/wicketlinkgt
• lt/wicketheadgt
• ltwicketpanelgt
• ltinput wicketid"password" type"password" /gt
  ltspan wicketid"strength"gtstrengthbarlt/spangt
• lt/wicketpanelgt

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PSI - Java

• public class PasswordField extends Panel
• public final static String WEAK "weak"
• public final static String MEDIUM "medium"
• public final static String STRONG "strong"
•  
• public PasswordField(String id, IModel model)
• super(id, model)
• PasswordTextField passwordTextField new
  PasswordTextField("password", model)
• add(passwordTextField)
•  
• final Label strength new Label("strength",
  "")
• add(strength)
• strength.add(new AttributeModifier("class",
  true, new Model()
• public Object getObject()
• return getPasswordStrength(PasswordField.this.
  getModelObjectAsString())
• ))
•  
• strength.setOutputMarkupId(true)

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PSI - TestPage

• public class TestPage extends WebPage
• private String password
• public TestPage()
• Form form new Form("form")
• form.add(new PasswordField("password", new
  PropertyModel(this, "password")))
• add(form)

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Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• Summary
• QA

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Summary

• Component oriented web application framework
• Just Java and HTML
• Easy Ajax
• Enthusiastic community

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Community

• http//wicket.apache.org
• users_at_wicket.apache.org
• wicket_at_irc.freenode.net

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Future Wicket NEXT

• Java 5 based
• Generics (already in)
• Varargs?
• Typesafe PropertyModel
• New WicketTester
• Based on JDave/Hamcrest
• Many more cool features

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Books
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Agenda

• What is Wicket?
• Core Concepts
• Developing a custom Component
• QA

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Thank you for yourattention