Vaadin+Scala

- Simple programming model- Secure- No javascript- Beautiful

Why?

Simple programming model

- Abstracted from HTTP- No request/response/session mess- All AJAX- Just a web page

Secure

- All server-side- Validations- No code on client- CSRF, XSS protection built-in

No javascript

- No bad parts- Good parts still accessible- Built on GWT- Large test suite for each browser

Beautiful

- Mature codebase- Thinking of U and I- Widgets and addons- Themes

Performance

- Almost every event is handled on server- Optimized wire format- No page reload- Static content

Performance vs PrimeFaces

Scalability Study - QuickTickets

+Scala

mandatory ugly java slide

6 class TransactionPage(controller:TransactionController=new TransactionController) extends BasePage { 7 model.params = params 8 compositionRoot = new VerticalLayout { 9 val form = new Form { 10 caption = 'hello 11 val beanItem = new BeanItem(model) { 12 item = this 13 visibleItemProperties = propertyIds().filter(_ != "progress") 14 } 15 field("price").foreach { p => 16 p.required = true 17 p.validators += >=(10.0) 18 } 19 } 20 components ++= 21 Button('check, Notification.show(model.toString)) :: 22 Button('start, validated(form)(controller.start(done))) :: 23 form :: 24 new ProgressIndicator {property = form.beanItem.property("progress")} :: 25 Nil 26 } 27 def done = Notification.show('done, Type.Tray) 28 def model = controller.model 29 }

+Scala

- wraps Vaadin api into idiomatic Scala- closures, Options, etc.

+Scaladin

+Scala => declarative

- comparable to JSON1 {"transactionPage": { 2 "controller": "TransactionController", 3 "compositionRoot": { 4 "type": "VerticalLayout", 5 "components": [ 6 { 7 "type": "Button", 8 "caption": "hello"

.... 9 } 10 ] 11 } 12 }}

- no need to reference view from controller- statically checked- support for HTML templates

+Scala => inline constructorsclass TransactionPage(controller: TransactionController = new TransactionController) extends BasePage {

//body goes here

}

+Scala => DelayedInit

8 trait BasePage extends CustomComponent with Validations with DelayedInit { 9 var params: String = "" ...

16 def init(params: String) = {

17 this.params = params 18 initCode.foreach(_()) 19 } 20 }

14 case class TabView(name: String)(content: => Seq[Component] = stubContent(name)) 15 extends VerticalLayout with View { 16 def enter(event: ViewChangeEvent) { 17 //showing that state persists and lazy loading is possible 18 val params = event.getParameters 19 content.collect {

20 case page: BasePage => add(page).init(params) 21 case view => add(view) 22 } 23 Notification.show("Entered " + name + " with params " + params) 24 } 25 }

class TransactionPage(controller: TransactionController = new TransactionController) extends BasePage {

model.params = this.params

+Scala => callbacks and HOFsButton('start, validated(form)(controller.start(done)))

def apply(caption: String, clickListener: => Unit): Button

def validated(form: Form)(action: => Unit)

def start(done: => Unit)

- increase code reuse- decrease coupling

+Scala => symbols

- localization- natural namescaption = 'hello

implicit def translateSymbol(s: Symbol) = s"${s.name} locale:${self.locale}"

implicit def translateTuple[T](s: (Symbol, T)) (implicit toParams: T => TranslationParams) = translateSymbol(s._1).format(toParams(s._2).p: _*)

validators += >=(10.0)

def >=[T](bound: T)(implicit ord: Ordering[T]): Option[Any] => Validation = { import ord._; v => v match { case Some(v: T) if v >= bound => Valid case _ => Invalid(Symbol("should be greater %s") -> bound :: Nil) } }

+Scala => structural types

- navigate in nested objectsval form = new Form { val beanItem = new BeanItem(model) {

...

form.beanItem.property("progress")

- eliminate dependenciestrait Translation {self: {def locale: Option[Locale]} =>

+JRebel

- Reloading classes as if they were templates- Free for Scala- Free for Vaadin Pro users

Thank you!Q&A