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From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: TCP Urgent Mode.
Keywords: TCP, URG, RFC793
Message-ID: <3386@auspex.auspex.com>
Date: 25 May 90 18:25:03 GMT
References: <151@matrix.UUCP>
Distribution: na
Organization: Auspex Systems, Santa Clara
Lines: 16

>If one were to implement the TLI API on top of TCP and were to provide the
>
>	t_rcv(fd, buf, nbytes, flagsp)
>
>call, how would they be able to provide T_EXPEDITED data?

TCP doesn't really have expedited data in the same way that, say, TP4
does; it has an urgent pointer.

>TLI appears to treat normal and expedited data as two independent streams.

Yup.  S5R4's streams code implements the notion of a "marked" message
for precisely that reason; that's how it handles the urgent pointer.  It
may also support the notion that the last byte of urgent data is treated
as expedited data, as per, say, 4.2BSD, and 4.3BSD when SO_OOBINLINE
isn't set.