Just found an old post about Processing talking to Flash in actionscript 2, been working on an actionscript 3 version. I'm pretty new to using Processing but I thought I would share with you what I have. It's working for me hopefully it can help some of you. I had a look for another post similar but had no luck. So here is the code.

Processing Code
Code:

import processing.net.*;

int port = 9001;
Server myServer;
//Variables for Sending
byte zero = 0;
int total = 299;
int total2 = 200;

void setup() {
  size (200, 200);
  myServer = new Server(this,port);
}

void draw () {
  total += 1;
  total2 +=2;
  myServer.write(total+","+total2);
  myServer.write(zero);
} 

Actionscript 3
Code:

package {

import flash.display.Sprite;

import flash.events.Event;

import flash.events.DataEvent;

import flash.events.IOErrorEvent;

import flash.net.XMLSocket;


public class serverCom extends Sprite {




public var serialServer:XMLSocket;




public function serverCom() {



init();


}


public function init():void {



serialServer=new XMLSocket  ;



serialServer.connect("127.0.0.1",9001);




serialServer.addEventListener(DataEvent.DATA,onReceiveData);




serialServer.addEventListener(Event.CONNECT,onServer);



serialServer.addEventListener(Event.CLOSE,onServer);



serialServer.addEventListener(IOErrorEvent.IO_ERROR,onServer);


}


// --== EVENTS ==-- \\


public function onServer(event:Event):void {



trace(event);


}


public function onReceiveData(dataEvent:DataEvent):void {




var Data:DataEvent=dataEvent;



//trace(Data);





// This grabs the data from Data var which is the string passed



// from our processing server.



var test=Data.data;



//trace(test);






// This splits the variables we are passing.



var parts:Array=test.split(",");



trace("parts0 this is the first variable: " + parts[0]);



trace("parts1 this is the second variable: " + parts[1]);


}

}
} 

Good Luck
Happy Coding =D