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Communication between AS2 and AS3[basic]

As soon as ActionScript3 saw the light of the day Adobe instantly pointed out that the virtual machine behind it is completely different than the one used in AS2, which in turn means there is no direct way of communicating between those two languages. Right now someone might think that if that is the case, then there is no point in trying, topic closed. But wait a second, no direct connection doesn't equal to no possible connection at all. Let me put it this way: lets take MySQL for example, Flash doesn't come packed with any means to connect to it directly, yet it doesn't stop us anyway, thanks to PHP (or other methods). Which brings us to the heart of the matter: indirect connection. In case of AS3 and AS2 it is even simpler than using PHP, because both of them include a class for communication between local SWF files - LocalConnection is its name.
Main purpose of LocalConnection is to communicate between two Flash applications running on the same computer, however since its implementation did not change at all in AS3, we can also use it to establish a connection between AS2 and AS3.
Creating a LocalConnection is very easy and almost identical for both languages. For ActionScript2 it will be:
var connectionAS2:LocalConnection = new LocalConnection();
And for ActionScript3:
var connectionAS3:LocalConnection = new LocalConnection();
connectionAS3.client = this;
function onStatus(e:Event):void { }
AS2 version is quite trivial, however AS3 one requires some explanation. First of all, the line that says connectionAS3.client = this; is very important as it points to object that will handle the incoming function calls, without it the application will simply not work. StatusEvent is added to the LocalConnection only to stop Flash from throwing any errors before the connection is established.
Oh and texts put into the connect() functions are different to allow for bidirectional communication.
Okay, now that we have AS2 and AS3 ready to exchange commands, it is time to create function that will send them. Also, to get a better feedback on the whole process we will include TextFields to display the information. For ActionScript3 it will be:
var tf:TextField = new TextField();
tf.text = "No Messages";

function messageFromAS2(msg:String,nx:Number,ny:Number):void {
	tf.text = msg+" "+nx+" "+ny;
	tf.x = nx;
	tf.y = ny;
While for ActionScript2 it will be:
var tf:TextField = this.textMsg;
tf.text = "No Messages";

connectionAS2.messageFromAS3 = function(msg:String,nx:Number,ny:Number):Void {
	tf.text = msg+" "+nx+" "+ny;
	tf._x = nx;
	tf._y = ny;
One last thing remaining now is to fire up those functions - Mouse Events will do the trick. For ActionScript3:
function onMove(e:MouseEvent):void {
	try {
		connectionAS3.send("LocalConnectionTestAS2","messageFromAS3","AS3 MouseEvent",e.stageX,e.stageY);
	} catch(e:Error) {
For ActionScript2:
this.onMouseMove = function():Void {
	try {
		connectionAS2.send("LocalConnectionTestAS3","messageFromAS2","AS2 Mouse Event",_root._xmouse,_root._ymouse);
	} catch(e) {
In both cases try-catch is used to stop Flash from throwing errors before the connection is established.
In action, the whole thing will look like this:
Source code:

By the way, if you ever find yourself in a situation where you need to access an AS2 file that does not support LocalConnections and can't be modified, I suggest creating a separate SWF file in ActionScript2, then loading (loadMovie() function) the target file to read all the necessary information and send them further down the line wherever you like using LocalConnection.