RE: Socket program problem

[Chris Bipes <chris.bipes@xxxxxxxxxxxxxxx>]

Don't know why buffer sizes would matter but it sounded like he was using
one write statement to send all the records from one large program buffer
and possibly over running the TCP job buffer.  It sounded I agree TCP
ensures the packets arrive in sequence which is why I asked if it was UDP or
TCP.  It could also be that the data is delayed to the client do to a busy
router/firewall and the client is timing out.  I would like to know if the
delay of the close fixed the problem and if it is tcp or udp.

Chris Bipes

-----Original Message-----
From: Scott Klement [mailto:klemscot@xxxxxxxxxxxx]
Sent: Monday, September 08, 2003 11:55 AM
To: Midrange Systems Technical Discussion
Subject: RE: Socket program problem




On Mon, 8 Sep 2003, Chris Bipes wrote:

> Look at your TCP Buffers Sizes one the individual machines.  Also look at
> the network configurations.  Are there routers / fire walls between the
> AS400 and the PC on some on the networks?  Can you see any patters in the
> network layout or TCP Buffer sizes?

Why would buffer sizes matter?  I would agree with you if he were getting
WSAEWOULDBLOCK...

> It sounds like the packets are arriving out of sequence and the close
> is arriving before all the data is processed by the PC.  Is this UDP or
> TCP connection?

TCP ensures that packets are received in the same order they are sent.
Two of the most commonly used interrnet protocol, FTP and HTTP, both
use the socket closing as an indication that the data has all been sent.
Therefore, the closing of the socket MUST work without losing data...

However, if SO_LINGER is set improperly, and the packets are received out
of sequence, it's possible that the server is no longer listening to
re-send the bad ones.   But, with SO_LINGER at it's default value, this
shouldn't happen.

UDP could get the packets out of order, but closing the socket wouldn't
cause data to be dropped in UDP, since it's not expecting an ack of the
data.  (Not only that, but you wouldn't want to close the socket at all if
it were UDP, since you use the same socket for every client that sends a
packet)