11 AJAX and Comet in Lift

import _root_.net.liftweb.http.SHtml._
// The next two imports are used to get some implicit conversions
// in scope.
import _root_.net.liftweb.http.JE._
import _root_.net.liftweb.http.JsCmds._
// Use logging facilities
import _root_.net.liftweb.util.Log
​
// define a snippet method
def myFunc(html: NodeSeq) : NodeSeq = {
  bind("hello", html, "button" -> ajaxButton(Text("Press me"), {() => 
    Log.info("Got an AJAX call")
    SetHtml("my-div", Text("That’s it")) 
  })
}

​
class SimpleSnippet {
  import _root_.net.liftweb.http.js.{JE,JsCmd,JsCmds}
  import JsCmds._ // For implicits
  import JE.{JsRaw,Str}
​
  def ajaxFunc1() : JsCmd = JsRaw("alert(’Button1 clicked’)")
​
  def ajaxFunc2(str: String) : JsCmd = {
    println("Received " + str)
    JsRaw("alert(’Button2 clicked’)")
  }
​
  def ajaxFunc3() : JsCmd = JsRaw("alert(’Button3 clicked’)")
​
  def renderAJAXButtons(xhtml: Group): NodeSeq = {
    bind("ex", xhtml,         
            "button1" -> SHtml.ajaxButton("Press me", ajaxFunc1 _),
            "button2" -> 
              // ajaxCall and ajaxInvoke actually returns a pair (String, JsExp). 
              // The String is used for garbage collection, so we only need
              // to use the JsExp element (_2).
              <button onclick={SHtml.ajaxCall(Str("Button-2"), ajaxFunc2 _)._2}>
                Press me 2</button>,
            "button3" -> 
              <button onclick={SHtml.ajaxInvoke(ajaxFunc3 _)._2}>
                Press me 3</button>)
 }
}
​

import scala.actors._ 
import scala.actors.Actor._
​
object PingPong extends Application {
  var count = 0;
  val pong = actor {
    loop {
      react {
        case Ping => println("Actor Pong Received Ping")
          sender ! Pong
        case Stop => println("Stopping Pong")         
          exit()
       }
    }
  }
  val ping = actor {
    pong ! Ping
    loop {
      react {
        case Pong => println("Actor Ping Received Pong")
           count = count + 1;
        if (count < 3) {
          sender ! Ping
        } else {
          sender ! Stop
          println("Stopping Ping")
          exit()
        }
      }
    }
  }
}
case object Ping 
case object Pong 
case object Stop

<lift:surround with="default" at="content">
    <lift:comet type="Clock" name="Other">
        Current Time: <clk:time>Missing Clock</clk:time>
    </lift:comet>  
</lift:surround>

package com.myapp.comet
​
class Clock extends CometActor {
  override def defaultPrefix = Full("clk")   
​
  def render = bind("time" -> timeSpan)
  
  def timeSpan = (<span id="time">{timeNow}</span>)
​
  // schedule a ping every 10 seconds so we redraw
  ActorPing.schedule(this, Tick, 10000L) 
​
  override def lowPriority : PartialFunction[Any, Unit] = {
    case Tick => {
      println("Got tick " + new Date());
      partialUpdate(SetHtml("time", Text(timeNow.toString))) 
      // schedule an update in 10 seconds
      ActorPing.schedule(this, Tick, 10000L) 
    }
  }
}
case object Tick

case class SubscribeClock(clock : Clock)
case class UnsubClock(clock : Clock)
​
object ClockMaster extends Actor {
  private var clocks : List[Clock] = Nil
  def act = loop {
    react {
       case SubscribeClock(clk) =>
        clocks ::= clk
      case UnsubClock(clk) =>
        clocks -= clk
      case Tick =>
        clocks.foreach(_ ! Tick)
    }
  }
}

...
override def localSetup {
  ClockMaster ! SubscribeClock(this)
  super.localSetup()
}
override def localShutdown {
  ClockMaster ! UnsubClock(this)
  super.localShutdown()
}

bind("admin", xhtml, "tick" ->
     SHtml.ajaxButton("Tock!", {
        () => ClockMaster ! Tick
     }))