Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!munnari!otc!metro!ipso!runx!avenger
From: avenger@runx.ips.oz (Troy Rollo )
Newsgroups: comp.sys.apollo
Subject: Re: IPC vs. SOCKET
Message-ID: <2123@runx.ips.oz>
Date: 22 Apr 89 23:36:08 GMT
References: <42b9642b.b11a@falcon.engin.umich.edu>
Organization: RUNX Un*x Timeshare.  Sydney, Australia.
Lines: 29

> Are there any comments on the relative merits of working
> with Apollo C socket calls and/or Apollo IPC calls?  Any
> good or horror stories?  Why are both supported?  Thanks for
> the info.

	I found that the Apollo ipc_$ calls were easier to manage. The
BSD socket calls require a lot of mucking about with protocols, and if
you are a mortal user working with the network you really need to convince
your admin to put a line in /etc/services on each host for you.
	With ipc_$ calls, you don't much about with socket and port numbers,
just socket handles and file names. I named my sockets for receiving as
//node/sys/node_data/tmp/sock_name, where node is the destination node if
I knew which node I was sending to, or was a known node which everybody used
for this purpose if I didn't (the file server).
	The help files for ipc_$ calls say that messages are not guaranteed
to arrive in order, only once or even at all, but I have never seen a message
fail to arrive at all (I have seen them arrive out of order and multiple
times however).
	The disadvantage with ipc_$ calls is that if the data must get to
its destination, and must get there in order and without duplicates, you
have to add your own protocol, but a simple ack/nak with block numbers
as per TFTP should do the job.

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