Re: RFC1122 conformance question

kurt@unirsvl.rsvl.unisys.com Thu, 01 October 1992 20:50 UTC

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Subject: Re: RFC1122 conformance question
To: ietf-hosts@nnsc.nsf.net
Date: Thu, 01 Oct 1992 14:03:02 -0500
Cc: 4jde@uunet.uu.net, braden@isi.edu, kurt@uunet.uu.net
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From: kurt@unirsvl.rsvl.unisys.com

> > > 
> > > Question: If the TCP receives an urgent input and queues the urgent input with
> > > an indication that it is urgent on the application's input queue, does this, in
> > > your opinion, conform to the above excerpt from RFC1122?
> > > 
> > 
> > In my opinion, no.  The Urgent interface to the application layer is
> > intended to solve the problem of the application NOT reading its input,
> > eg because it is looping or otherwise mis-behaving.  Urgent is intended
> > to activate an asynchronous thread (in practice, in the Telnet under-
> > belly of the application layer) to unstick things.
> 
From my understanding I thought that the asynchronous notification was needed
because in the standard UNIX environment there is only one activity/process per
connection. This creates the problem where the activity/process can be 
looping, or just doing output without checking to see if there is input to
process. Since in the case that I described there is an activity dedicated to
processing input, this problem doesn't exist. Therefore I would think that
in my case, the asynchronous notification would be not applicable instead of
a non-conformance. How does that sound?
> 
> 
> > 
> > From your description of the host operating system environment, I gather
> > that this is not a general-purpose host, which is the intended domain of
> > RFC-1122. 
> 
> No, this is not a special purpose host, it is the standard Unisys 2200      
> mainframe. We have been doing things this way for over 10 years. The 2200 
> mainframe has been a multiprocessor machine for approx 20 years.
> It is possible for a general purpose host to be something other than a single
> processor UNIX box. :-)
> 
> >                 (But what happens if the application DOES go into a
> > loop and stop reading its input?)
> 
> I would assume that it would be the same as if the asynchronous thread did the
> same thing. You always have this possibility.
> 
> Since you cc'd the other WG, I pulled it out of the header and am sending this
> there also. Thanks for your reply.
> 
Kurt Matthys
Unisys Corp
kurt@rsvl.unisys.com