IPC and queueing messages

[Doug Bagley]

I have a question about IPC in Ultrix 2.0.  I have a distributed (over
internet) application that does a lot of message passing.  The behavior
that I want is for the sender to never block on a send -- the message
should just be queued somewhere -- and receivers would just read from the
queue.  Sockets are just the thing, but in Ultrix 2.0, the high watermark
is too low.  I can queue about 7K of data before the sender blocks.  For
my application, I'd like to be able to queue about 100K as a maximum, but
more commonly it would be about 20-40K.

Well I gave a quick look in include/sys/ioctl.h and there is an ioctl
call -- using SIOCSHIWAT -- which supposedly increases the high
watermark.  However, I am unclear as to when the ioctl call should be
made, if it requires root privilege, or what.  Whenever I call it I get
the error "Can't assign requested address".  I'm pretty much in the dark.
I can't find anything about this sort of stuff in the regular Ultrix
manuals.

Obviously I'm looking in the wrong place.  Anyway, if someone out there
can point me in the right direction on this, I'd be very appreciative.
Alternatively, if anyone has ideas about a more fruitful direction to
take to get messages queued, I am open to all suggestions.

Thank you,
Doug Bagley

protmiwsia
(please reply only to me, i will summarize if appropriate)
__________________________________________________________________
CSNET:  bagley at temple.edu    ARPA(flaky):  doug at ws5.cis.temple.edu