What is the (best) way to poll a server for TCP data?
Server sents notifications, whitch i want to pick up.
Do you leave the socket open all the time, waiting for a notification. Ive tried this by opening a async socket but cant/dont get any onData information.

ModEdit - LRM - Added content to the title to make future searches easier.

Receiving asynchronous events (which is really what you are asking) is typically accomplished by keeping socket connected throughout usage of the activity.

What is the protocol? HTTP? Web Service? You have really not given us enough detail here.
//20120213 - bugfix to assign socket initially so that we can hook callbacks.

var socket;
var buffer = '';

function cleanSocket()
{
if (null === socket)
return;
try
{
if (socket.connected)
socket.close();
}
catch(e)
{
System.print('Error closing socket! e:' + e);
}
socket.onData = null;
socket.onConnect = null;
socket.onIOError = null;
socket.onClose = null;
// release the activity based variable.
socket = null;
}

function onData()
{
buffer += socket.read(); // must read in onDataCall
// process buffer after read to pull off complete messages
// write any messages as needed.
//call cleanSocket() to shutdown as needed.
}

function onIOError(e)
{
System.print('Socket IO Error e:' + e);
cleanSocket();
CF.activity().scheduleAfter(500, doConnect, null);
}

function onClose()
{
System.print('Socket closed from remote side');
cleanSocket();
CF.activity().scheduleAfter(500, doConnect, null);
}

function onConnect(newSocket)
{
// if using socket.listen(), newSocket will be the new client socket just connected.
socket.write('MV?\r'); // this is of your own doing - example is to query denon for master volume.
}

function doConnect()
{
socket = new TCPSocket();
socket.onData = onData;
socket.onIOError = onIOError;
socket.onClose = onClose;
socket.onConnect = onConnect;
socket.connect('192.168.1.55', 23, 3000); // Connect to port 23 on the Denon.
}

doConnect();

Lyndel,
Thnx for the elaborate reply!
Im building my own script for Logitech Media server. The server listens on port 9090 for TCP/IP connections. I can control the squeezebox allready, but getting notifications was proving difficult (for me).
Furthermore i dont use the onClose, because the server doesnt close the socket. It stays open. With "\n" as last character the server signals the end of the reply.
Anyway thnx again. This forum would be dead if it wasn't for you!
(No offence to others, but you get my drift)

jeroen

Shortent code:
function tcpcom(){
if(LMSsocket != null){System.print("Closing socket first");LMSsocket.close(); LMSsocket=null}
LMSsocket = new TCPSocket(false);
LMSsocket.onConnect = function(){LMSsocket.write(command)}
LMSsocket.onIOError = function (e) {GUI.widget("ERRpanel").label = "IOError " + e}
LMSsocket.onData = function(){result += LMSsocket.read(); resultlen = result.length;
if(result.substr(resultlen-1) == "\n"){result = result.substr(0,resultlen-1);
switch(check){
case "Player 0 ID":PlayerID = decodeURIComponent(result.substr (comlen+1)); GUI.widget("L1").visible=true;Terminate();break
//.....
}}}
LMSsocket.connect(LMS.host, LMS.TCPport, LMS.duration);
}

function Terminate(){
if(LMSsocket!=null){LMSsocket.close();LMSsocket=null;}
}

Why not just pay the $29.95USD to Barry for SqueezePronto or to Nick Riley for ProntoSqueeze (I may have names backward).

I, too, use the CLI interface but do so only for 1-way control.

Its a challenge.and programming is my hobby.

Lyndell,

Im trying to get your example to work. I understand whats happening, only cant get it to wordk.
Can you give me a page script to approach your script (firing a command at page level). Also the listen() function ???

jeroen

Put my updated code above either into an activity or into a page that does not repeat. As an exercise, you might want to use the old code and then call System.setDebugMask(9); at the activity level and then put my script into a page. This will help you understand what the original problem was. An error was being thrown as soon as we executed socket.onData = function(){...}. The issue was that socket had not been initialized at this point.

Note that my example ONLY works with a Denon receiver at a particular IP and port 23. You will need to adjust both of these in the doConnect function.

I have corrected a few bugs above to correct my previous issues. Please use the updated code.

Ill give it a try this week.
Thanks for updating!


One-way Logitech Media server is working (not bug free, but getting there).
Now I only want the elapsed time to appear. Tried active polling with the elapsed time command. But that gives problems with the socket opening and closing correctly. For a time it goes well, but suddenly it skips a close and goes haywire...

Implemented your script.
Putting commands in de onConnect call and active play-time polling from the Page script is working stable. First had a lot of "Socket not ready" errors but after changing the script sequence there gone (hopefully forever... ;-) )
Couldnt have pulled it off without your help.
Thx again!
jeroen