pnet TCP connection bug

Fan Li — Fri, 10 Oct 2008 06:21:48 -0400

I am using the latest 2.0.6 version of TCP/UDP/IP toolbox (pnet) on
Matlab R2008a with Win XP Pro SP3. I am setting up a pair of tcp
sockets on localhost to send/receive short messages. The overarching
goal is to have a server-client style communication between two matlab
processes for data acquisition during visual experiments.

Here are example code (one for the server side and one for client):

server side:
sockcon = pnet('tcpsocket', 8889); % only create this socket once
quit = false;
while ~quit
    serv=pnet(sockcon,'tcplisten', 'noblock');
    if serv ~= -1
        % if someone connected to this data socket
        pnet(serv,'setreadtimeout', 1);
        received = pnet(serv,'readline','noblock');
        received
        pnet(serv, 'close');
    end
end

client side:
sockcon = pnet('tcpsocket', 8888); % only create this socket once
con=pnet('tcpconnect','localhost',8889);
pnet(con,'setwritetimeout', 1);
cmd = 'here is a test command';
pnet(con,'printf', '%s\n', cmd);
pnet(con, 'close');

To run, create both sockets (one in each matlab process), then let the
server-side loop while listening for a tcp connection. The client side
code sends a command to the server, which should be picked up by the
"readline".

The odd behavior that I am getting is that sometimes the server
successfully receives the message, but sometimes returns an empty
string from the readline command. It seems to be random, and I cannot
see a pattern in when it returns empty string versus the correct
string.

Can anyone duplicate this or has anyone seen this kind of behavior
before?

Thanks,
Fan

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pnet TCP connection bug