NetNews Usenet Archive 1992 #19/NN_1992_19.iso/spool/comp/sys/transput/969

Text File | 1992-08-31 | 1.8 KB | 33 lines

Newsgroups: comp.sys.transputer
Path: sparky!uunet!haven.umd.edu!darwin.sura.net!Sirius.dfn.de!rz.ruhr-uni-bochum.de!jan
From: [e-mail] (Jan Vorbrueggen)
Subject: Re: Usage of in/out concerning iserver packets?
Message-ID: <[e-mail]>
In-reply-to: [e-mail]'s message of Sun, 30 Aug 92 13:04:21 +0100
Organization: Inst. f. Neuroinformatik, Ruhr-Universitaet Bochum, FRG
References: <[e-mail]>
Date: 31 Aug 92 15:22:50
Lines: 21

   While learning assembler, I wondered about how iserver is supposed to be
   used.  If two processes communicate with each other, the length of
   corresponding 'in's and 'out's has to be same, right?  For the root
   transputer exchanging data with the host, that doesn't matter, but what
   for a router process which transports iserver packets between processes,
   e.g. to simulate a virtual transputer network?

   > In OCCAM these messages can be routed as INT16::[]BYTE protocol.

And this means that two seperate communications are performed: one,
transferring 2 bytes (an INT16) designating the length of the following
byte stream. The internal structure of a packet (eg, a PUTBLOCK or what
ever) is irrelevant to the router and is of concern only to the end users.
The aim is to reduce the necessary INs and OUTs and their associated
overhead  it's easier to have the sender pack it all into a byte array
and for the receiver to unpack it. Additionally, it's easy to extend the
protocol (apart from maximum buffer sizes) such that only interested parties
have to take note  a router doesn't and shouldn't care. The only things you
might want to add is addressing and possibly, control over multi/broadcasting.

 Jan Vorbrueggen, [e-mail]