Question

I read the documentation, but it is not clear whats the difference between bind() and connect() methods.

Answer 1

bind() causes the socket to listen for incoming requests on a particular interface/port. In other words, it’s used by servers to respond to incoming requests. Only one socket can bind a port.

connect() causes the socket to make a connection to an address/port serviced by a different socket. In other words, it’s used by clients to connect to a server. Multiple clients can connect to a port. NOTE: connect() is not required for use with UDP (datagram) sockets, only TCP/IP. UDP is a broadcast protocol, and connect() does not even require that a socket is listening to the other end.

Something like this (adapted from the docs and untested) should send and receive the message “Hello, turnip!” to itself on port 12345:

package
{
    import flash.events.DatagramSocketEvent;
    import flash.net.DatagramSocket;

    public class TestClass
    {
        private var serverSocket:DatagramSocket = new DatagramSocket();
        private var clientSocket:DatagramSocket = new DatagramSocket();

        public function TestClass():void
        {
            this.serverSocket.bind(12345, "127.0.0.1");
            this.serverSocket.addEventListener(DatagramSocketDataEvent.DATA, dataReceived);
            this.serverSocket.receive();

            send("Hello, turnip!");
        }

        public function sendData(message:String):void
        {
            var data:ByteArray = new ByteArray();
            data.writeUTFBytes(message);

            try
            {
                clientSocket.send(data, 0, 0, "127.0.0.1", 12345);
                trace("sending:  " + message);
            }
            catch (error:Error)
            {
                trace(error.message);
            }
        }

        private function dataReceived(e:DatagramSocketDataEvent):void
        {
            var data:String = e.data.readUTFBytes(e.data.bytesAvailable);
            trace("received: " + data);
        }
    }
}