Providing Version Synchronization for Deployed Rich Internet Applications

<cfcomponent>
   <cffunction name="getVersion" returntype="numeric" output="false" access="remote">

      <cfreturn 1>
   </cffunction>

</cfcomponent>

//Tell flex we intend to broadcast two events
[Event("checkVersion")]
[Event("updateVersion")]

class SimpleVersionManager extends Object {
  private var _pollTime:Number;
  private var _applicationVersionNumber:Number;
  private var _latestVersionNumber:Number;

  private var pollInterval:Number;

  public var addEventListener : Function;
  public var removeEventListener : Function;
  private var dispatchEvent : Function;

  /* The requestVersionCheck function is called periodically 
     via the SetInterval. It dispatches an event asking for 
     the latest version of the software available */
  private function requestVersionCheck() {
    //Cancel our current interval.
    //We will wait for a response before we ask again
    clearInterval(  pollInterval  );

    //We need to find out the current version of this software
    this.dispatchEvent({type:"checkVersion",target:this});
  }

  /*getter/setter functions for the version number 
    of this application  */
  public function set applicationVersionNumber( value:Number ):Void {
    //This is the version number of our local application
    _applicationVersionNumber = value;
  }

  public function get applicationVersionNumber():Number {
    return _applicationVersionNumber;
  }

  /* getter/setter functions for the latest version number of 
     this application according to an outside authority  */
  public function set latestVersionNumber( value:Number ):Void {
    //This is the latest available version number of the application
    _latestVersionNumber = value;
    
    //We check if we are up to date
    if ( applicationVersionNumber < latestVersionNumber )    {
      //We need to update.  We inform whomever may be listening
      this.dispatchEvent({type:"updateVersion",target:this});
    } else {
      //We have a current version for the moment.
      //We will check again later
      pollInterval = setInterval( this, "requestVersionCheck", pollTime ); 
    }
  }

  public function get latestVersionNumber():Number {
    return _latestVersionNumber;
  }

  //getter/setter functions for our polling interval
  public function set pollTime( value:Number ):Void {
    if ( value < 1000 ) {
      /*For our purposes, we are going to constrain the poll 
        period so that it cannot be less than a second
        in practice, this should be much, much longer
      */
      value = 1000;
    }
    
    _pollTime = value;
  }

  public function get pollTime():Number {
    return _pollTime;
  }

  /*We call this method when we are ready to begin 
    managing the version of our application */
  public function manageVersion()  {
    /*immediately request a version check on startup.  
      we want to find out if a new version exists before 
      the user gets to far into using the application */
    requestVersionCheck();
  }

  function SimpleVersionManager() {
    //Initialize the event broadcaster
    mx.events.EventDispatcher.initialize(this); 
  }
}

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.macromedia.com/2003/mxml" xmlns="*" creationComplete="initialze( event );">
  <mx:Script>
  <![CDATA[
  //For the moment we have statically set a version
  //number in our application
  var ourVersion:Number = 1;
  
  function queryServerForVersion( event ) {
    /*  This function is called when SimpleVersionManager 
      broadcasts a checkVersion event */    
    versionService.getVersion();
  }
  
  function getNewVersion( event ) {
    mx.core.Application.alert( "Your version is outdated.  You have version " + versionManager.applicationVersionNumber + " and the server has " + versionManager.latestVersionNumber );
    
    /*Right now we have left this commented out
      However, the line below will redirect the browser to
      the url of your application */
    //getURL( "http://yourserver/virtual_pet2.mxml?version=" );
  }

  function setLatestVersion( event )  {
    /*This is called when we successfully retrieve the version number
      from the server.  Sets the latestVersion in the SimpleVersion Manager*/
    versionManager.latestVersionNumber = event.result
  }

  function initialze( event ) {
    /* This is caled by the Application creationComplete event.
       After everything is created, we start actively managing the version  */
    versionManager.manageVersion();
  }
  ]]>
  </mx:Script>

  <!--We setup a Remote Object to call our CFC on a ColdFusion Server-->
  <mx:RemoteObject id="versionService"
    endpoint="{yourServer}/flashservices/gateway?"
    source="versionCheck"
    showBusyCursor="false">

    <!--We are going to call the getVersion function in the cfc and 
        return the results to setLatestVersion-->
    <mx:method name="getVersion"
      result="setLatestVersion(event );"
      fault="mx.core.Application.alert('Problem Getting Version')"/>
  </mx:RemoteObject>

  <!--Instantiate a SimpleVersion Manager
    We pass it our applicationVersionNumber
    tell it we wish to check for a new version every 30 seconds
    (This is of course extreme, but it is an example)
    and tell it to call queryServerForVersion when a checkVersion event occurs
    and to call getNewVersion when an update version event occurs-->
  <SimpleVersionManager id="versionManager"
              applicationVersionNumber="{ourVersion}"
              pollTime="30000"
              checkVersion="queryServerForVersion( event );"
              updateVersion="getNewVersion( event );"/>

  <!--Spike-->
  <Dog id="myPet" 
      title="Virtual Pet RIA"
      petName="Spike"/>

</mx:Application>

//getURL( "http://yourserver/virtual_pet2.mxml?version=" );