AS3 - How to know when a Socket has no more data to return?

Question

I am trying to communicate using this protocol. It works fine except when the socket has a lot of data to return. Right now I am checking if a packet ends with \r\n to determine if I have received all the packages. Problem is that sometimes a package can end with \r\n as a line break even if it is not the last package, so I can not use that.

I am using a command queue, because I want to wait for a complete response before sending the next command.

The code with unnecessary stuff removed:

class CustomSocket extends Socket
{

    private var _response:String;
    private var _commandQueue:Array;

    public function CustomSocket()
    {
        super();
        this.addEventListener(ProgressEvent.SOCKET_DATA, socketDataHandler);
    }

    private function socketDataHandler(event:ProgressEvent):void 
    {
        readResponse();
    }

    private function readResponse():void {
        var str:String = this.readUTFBytes(bytesAvailable);
        _response += str;
        //BUG: I cannot use this check for determining the end of packets, need to find a new one
        if (_response.charAt(_response.length - 1) == "\n" && _response.charAt(_response.length - 2) == "\r")
        {
            //dispatch the result
            commandFinished();
        }
    }

    //writes to the socket
    private function sendRequest(request:String):void 
    {
        _response = "";
       this. writeln(request);
        flush();
        writeln("\r\n");
        flush();
    }

    private function writeln(str:String):void 
    {
        try
        {
            this.writeUTFBytes(str);
        }
        catch (e:IOError) 
        {
            trace(e);
        }
    }

    private function addCommand():void
    {
        //adds a command to the queue and executes it
    }

    private function commandFinished():void
    {
        //remove executed command and check if there is more commands in the queue to execute
    }
}

The problem is in the function readResponse. I've googled a lot without finding anything of interest.

Is there a way to know the total amount of bytes/packets a socket will return? Or a way to detect EOF or that a package is the last?

score 0 · Answer 1 · answered Oct 21 '11 at 15:41

Generally, a null character would be sent at the end of the data you are sending.
This gives your server a definitive character to look for.

this.writeln(request + String.fromCharCode(0) );

And just to let you know
You have a space after the dot in the function sendRequest on this line

this. writeln(request);

And you also might want to try this for error handling.

if(this.connected){
  this.writeln(request + String.fromCharCode(0) );
  this.flush();
}else{
  // do your error handling for no connection to server
}

score 0 · Answer 2 · edited May 23 '17 at 12:19

0

You're probably looking for the bytesAvailable property on Socket. As in:

while( socket.bytesAvailable )
    socket.readBytes( myByteArray );

For a more complete solution (including where it's possible to get multiple messages at once), I answered this in another question: AS3 / AIR readObject() from socket - How do you check all data has been received?

edited May 23 '17 at 12:19

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answered Oct 22 '11 at 12:51

divillysausages

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AS3 - How to know when a Socket has no more data to return?

2 Answers2