[PPT] - Te Lif Framework for Fun and Proft Peter Robinett PowerPoint Presentation

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Te Lif Framework for Fun and Proft

Peter Robinett peter@bubblefoundry.com for DUSE VI, 2010-06-30

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Who am I?

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Background in web programming with

interpreted languages (PHP, Python, Javascript, etc)

Likes long walks on the beaches
Lift + Scala programmer for one year
Loves both cats AND dogs
Lift committer for approx. 6 months BUT only

has minor commit to lift-flot to my name

Likes fine wine and smooth jazz
BUT active on mailing list and wiki
Isn't very good at making funny bullet points

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What i Lif?

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Lift is an expressive and elegant framework for writing web applications. Lift stresses the importance of security, maintainability, scalability and performance, while allowing for high levels of developer productivity. Lift is inspired by Seaside, Rails, Django, Wicket, and beyond.

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Why Fun?

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Comet

class AskName extends CometActor { def render = ajaxForm(<div>What is your username?</div> ++ text("",name => answer(name.trim)) ++ <input type="submit" value="Enter"/>) } class Chat extends CometActor with CometListener { private var userName = "" private var chats: List[ChatLine] = Nil private lazy val infoId = uniqueId + "_info" private lazy val infoIn = uniqueId + "_in" private lazy val inputArea = findKids(defaultXml, "chat", "input") private lazy val bodyArea = findKids(defaultXml, "chat", "body") private lazy val singleLine = deepFindKids(bodyArea, "chat", "list") // handle an update to the chat lists // by diffing the lists and then sending a partial update // to the browser

verride def lowPriority = {

case ChatServerUpdate(value) => val update = (value -- chats).reverse.map(b => AppendHtml(infoId, line(b))) partialUpdate(update) chats = value } // render the input area by binding the // appropriate dynamically generated code to the // view supplied by the template

verride lazy val fixedRender: Box[NodeSeq] =

ajaxForm(After(100, SetValueAndFocus(infoIn, "")), bind("chat", inputArea, "input" -> text("", sendMessage _, "id" -> infoIn))) // send a message to the chat server private def sendMessage(msg: String) = ChatServer ! ChatServerMsg(userName, msg.trim) // display a line private def line(c: ChatLine) = bind("list", singleLine, "when" -> hourFormat(c.when), "who" -> c.user, "msg" -> c.msg) // display a list of chats private def displayList(in: NodeSeq): NodeSeq = chats.reverse.flatMap(line) // render the whole list of chats

verride def render =

bind("chat", bodyArea, "name" -> userName, AttrBindParam("id", Text(infoId), "id"), "list" -> displayList _) // setup the component

verride def localSetup {

askForName super.localSetup } // register as a listener def registerWith = ChatServer // ask for the user's name private def askForName { if (userName.length == 0) { ask(new AskName, "what's your username") { case s: String if (s.trim.length > 2) => userName = s.trim reRender(true) case _ => askForName reRender(false) } } } }

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Te Community

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Why Proftable?

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Why Scala?

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All the normal reaons, plus...

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<lift:comet type=”Clock”> The time is <clock:time />. </lift:comet> class Clock extends CometActor {

verride def defaultPrefix = Full("clock")

// schedule a ping every 10 seconds so we redraw ActorPing.schedule(this, Tick, 10 seconds) private lazy val spanId = uniqueId+"_timespan" def render = { bind("time" -> timeSpan) } def timeSpan = (<span id={spanId}>{timeNow}</span>)

verride def lowPriority = {

case Tick => partialUpdate(SetHtml(spanId, Text(timeNow.toString))) ActorPing.schedule(this, Tick, 10 seconds) } } case object Tick

Actors

Allows great AJAX, Comet support.

BUT, there were issues with the EFPL library so David wrote

LiftActor. This is actually a proof of Scala's strength.

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XHTML Procesing

Template:

<lift:DuSE.sayHello> Hi <DuSE:name />. It's now <DuSE:datetime />. </lift:DuSE.sayHello>

Snippet:

import java.util.Date import scala.xml.{NodeSeq, Text} import net.liftweb.util.Helpers.bind

bject DuSE {

def sayHello(xhtml: NodeSeq): NodeSeq = { User.currentUser.map(user => { bind(“DuSE”, xhtml, “name” -> Text(user.shortName), “datetime” -> Text((new Date).toString) ) }) openOr <div>You didn't log in!</div> } }

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Routing

Routing is done via SiteMap...

LiftRules.statefulRewrite.prepend({ case RewriteRequest(ParsePath("app" :: appID :: "index" :: Nil, _, _,_), GetRequest, _) => RewriteResponse("app":: "view" :: Nil, Map("appID" -> appID) })

... and redirects with partial functions!

val entries = Menu(Loc(“App Page”, “app” :: “view” :: Nil, “App Page”) :: Nil LiftRules.setSiteMap(SiteMap(entries :_*))

Regex Free!

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What i Lif good at?

Comet, also AJAX
X(HT)ML processing
JSON
REST
As much or as little as you want done for you
Secure
Fast execution, fast development (IF you

already know Lift)

Great code:functionality ratio

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What i Lif bad at?

High learning curve
Stateless request/response cycle (but is

possible)

View-first, not MVC
I.E. Does some things differently
Statefulness can lead to lots of stuff in memory

if you're not careful

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By Markus Lütkemeyer http://flickr.com/photos/helico/2245863081/

How to get Lifed?

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A Digresion on Versions

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By Alan Sung http://flickr.com/photos/clsung/310886130/

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2.0-SNAPSHOT is quite stable
RCs are really stable, only important bug fixes are
added. We're at 2.0-RC2.
Milestones are very stable. Last one was 2.0-M6.
If you have crazy rules requiring that you MUST

use 'official' releases, wait a week for 2.0.

Moral of the story: DON'T use 1.x.
PS Scala 2.8 support in 280_port_refresh, should

see 3.0-SNAPSHOT after the 2.0 release.

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Join the Google Group

http://groups.google.com/group/liftweb

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Read the Getting Started Guide

http://www.liftweb.net/docs/getting_started.html

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Skim the Wiki

http://www.assembla.com/wiki/show/liftweb/

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Checkout the Scaladocs

http://scala-tools.org/mvnsites-snapshots/liftweb/

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Clone the code

http://github.com/lift/lift *

* Yep, since last night we've been using the new GitHub organizations

feature. We're cutting edge like that.

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Use an Archetye

lift-archetype-basic
lift-archetype-blank
lift-archetype-jpa-basic
lift-archetyp-jpa-blank-single
lift-archetyp-jpa-blank
lift-archetyp-sbt

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sbt

simple-build-tool is THE way to do Scala projects. See http://www.assembla.com/wiki/show/liftweb/Using_SBT OR git clone git://github.com/dpp/lift_sbt_prototype.git Then cd into lift_sbt_prototype and type: sbt At the sbt prompt, type: update Then: jetty-run Point your browser to http://localhost:8080/

Mads Hartmann is working on sbt processors for Google Summer of Code. It should be awesome.

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Maven

http://www.assembla.com/wiki/show/liftweb/Using_Maven

mvn archetype:generate \

DarchetypeGroupId=net.liftweb \
DarchetypeArtifactId=lift-archetype-blank \
DarchetypeVersion=2.0-SNAPSHOT \
DarchetypeRepository=http://scala-tools.org/repo-snapshots \
DremoteRepositories=http://scala-tools.org/repo-snapshots \
DgroupId=your.groupId \
DartifactId=your.artifactId

mvn jetty:run mvn scala:cc (jRebel license: http://www.zeroturnaround.com/scala-license/)

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Demo and Example

http://demo.liftweb.net/ http://github.com/lift/lift/tree/master/examples/ http://github.com/dpp/lift-samples http://www.liftweb.net

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Quetions?

By Gillian Maniscalco http://flickr.com/photos/gillian_m/448800043/