Re: Socket problem

[Scott Klement <klemscot@xxxxxxxxxxxx>]

> The communication is in fact between 2 servers on the same iSeries where
> one acts as a client to the other. The client socket does a Select() and
> a Read() but the Read() is reported to be returning without any error or
> data even though the socket at the other end can be to be still
> processing the request.

What are the parameters you're sending to select()?   Is it possible that
the select() is completing because of something other than a "socket is
readable" condition?

I'm not totally clear on what you mean when you say the socket on the
other end is still processing the request.   Do you mean it's still
sending data?   If so, it's normal for one side of the socket to start
receiving data before it's all written, assuming you're using a stream
socket (SOCK_STREAM)

If you're saying that the other side is processing a previous command that
was sent by a client, and has not yet written any data back, then I'd
guess that the select() is returning prematurely, and that you're using
non-blocking sockets, so read() is also returning immediately.

> What to do? Is it possible to do a communications trace between 2 such
> sockets?

I usually use a packet sniffer for such things, but if the two apps are on
the same system, that'll be difficult :)

You might try using a proxy as a go between, and logging the data to the
proxy, and/or simply testing each side of the connection manually with a
telnet client, and see if you can spot the error with that.  Those are the
tricks that I use.