UNIX System V Release n

[Doug Gwyn]

In article <422 at ubbpc.UUCP> wgh at ubbpc.UUCP (William G. Hutchison) writes:
>   many styles of networking: SunOS, TCP/IP, BSD sockets, streams;
>   multiple interfaces: curses, OPEN LOOK, NeWS, X11/NeWS;
>   more file system types: s5, BSD ufs, nfs, rfs, proc;
>   more types of inter-process communications: Xenix semaphores, sockets,
>        Sun RPC, Sys V ipc, named streams.

This list doesn't convey an accurate picture, because you have lumped
together different kinds of things, making it appear that there are more
choices in each category than there actually are.  For example, sockets
and streams are the two fundamental network connection technologies, and
it is even possible that in SVR4 sockets are emulated via streams.  The
main alternative to so-called "TCP/IP" (really, Internet protocol suite)
is OSI.  TCP itself is supported on sockets or streams, your choice
(I don't know which SVR4 chose; both implementations are known to exist).

The main reason for the wide variety is to support as many existing
applications as possible.  Existing applications were developed to
use any of a variety of technologies.  It is an expensive hassle to
have to change them to use a different technology.

Many of these varieties can be layered on a common base, and I expect
some of them will gradually fade away as applications are adapted to
use the more attractive ones.

For example, some might argue that RFS is technically a better UNIX
transparent remote file system technology, but NFS is too widespread
to ignore, so support for it is necessary.  (Also, they aren't quite
equivalent.  RFS implements full UNIX file system semantics; NFS aims at
a more generic level of file system so it includes MS-DOS, for example.)
RFS might eventually fade away, but then it might start catching on.

> (1) The market might reject Sys V Release 4 as too bulky (not likely, but
>     possible: this might move people to OSF/AIX),

Where you don't even HAVE streams?  Seems rather a silly decision.

> (4) Software houses might stick with their historical orientation:
>      BSD shops would only use the features of Rel 4 that are common to BSD,
>      Xenix shops would stick to the Xenix features, etc.

I'm sure that initially there will be this tendency.

> An alternative, semi-serious hypothesis: have Ritchie, Thompson, Kernighan,
>Plauger, et alii, been secretly working to re-invent Multics all these years
> :-) ?

No, and they haven't had all that much to do with the commercial UNIX
product either.  The Bell Labs research UNIX system is considerably
less featureful; several of its innovations have made it into the
commercial product, but the problem is that existing commercial UNIX
features are not being dropped at the same rate, probably because of
the perceived need to continue to support existing applications that
depend on the old cruft.