Date: Fri, 15 Nov 1996 11:58:51 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: fenner@parc.xerox.com (Bill Fenner) Cc: terry@lambert.org, fenner@parc.xerox.com, scrappy@ki.net, jdp@polstra.com, hackers@freebsd.org Subject: Re: Sockets question... Message-ID: <199611151858.LAA26626@phaeton.artisoft.com> In-Reply-To: <96Nov15.101231pst.177557@crevenia.parc.xerox.com> from "Bill Fenner" at Nov 15, 96 10:12:18 am
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> >> What you need to do is write all your data to the network,
> >> and not count on it arriving in the same sized chunks as you wrote it.
> >> But it will all arrive.
> >
> >This is (supposedly) what happens *for you* during packet reassembly
> >on the receiving end.
>
> No; what happens for you at the receiving end is that the packets get
> reassembled into the same *stream* of data as they were at the sender.
> The sender can buffer small writes into big chunks, or can fragment big
> writes. If the underlying MTU of the path changes, writes that didn't
> used to have to be fragmented may now have to be. Packet N can get
> lost in the network, while packets N+1, N+2, N+3 and N+4 arrive; when
> the sender retransmits packet N all of a sudden a ton of data "shows
> up" at the receiver. The receiver's job is *solely* to put those
> packets back together into the same stream as the sender sent.
So at the "read" interface, you *can* count on it arriving in the
same sized chunks as you wrote it, as long as the order and chunk size of
your reads is identical to those of your writes... in other words,
synchronized client and server automatons.
Right?
IF I issue a blocking read for 1000 bytes, AND
I issue a blocking write for 1000 bytes, AND
the blocking write returns "1000",
THEN the blocking read will return 1000 bytes OR
it won't return (EPIPE after connection timeout).
Karl is saying he has synchronized client and server automatons, but
that it's not working for large buffer sizes on the writes.
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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