This worked for me in the Flex 3 Eclipse environment. Once the connection is established you stay connected until the object is released. I just added an incoming message event listener to my code and it works fine:

var connection = new XMPPConnection();

var psce_on:Presence = new Presence( null, null, Presence.AVAILABLE_TYPE, Presence.SHOW_NORMAL, null, 1 );

var user1_msg:Message = new Message("user1@192.168.1.5", null, "Calling User1", null, Message.CHAT_TYPE, null);

var user2_msg:Message = new Message("user2@192.168.1.5", null, "Calling User2", null, Message.CHAT_TYPE, null);

var incoming_msg:Message = new Message("user2@192.168.1.5", null, "Incoming Data", null, Message.CHAT_TYPE, null);

public function XMPPconn(): void {

connection.username = "testcase";

connection.password = "xxxx";

connection.server = "server.com";

connection.resource = "xiff";

connection.addEventListener(LoginEvent.LOGIN, handleLogin);

connection.connect( "flash" );

}

private function handleLogin(event:LoginEvent):void{

connection.send(psce_on);

connection.send(user1_msg);

connection.send(user2_msg);

trace("Messages sent.");

}

private function handleIncomingData(event:IncomingDataEvent):void{

connection.send(incoming_msg);        &n bsp;            &nbs p;                           &n bsp;           

trace("Incoming");

             &n bsp; 

}