[TUHS] Were all of you.. Hippies?

Andrew Warkentin andreww591 at gmail.com
Sun Mar 26 13:01:22 AEST 2017


On 3/25/17, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>     > From: Ron Minnich
>
>     > There was no shortage of people at the time who were struggling to
> find
>     > a way to make the Unix model work for networking ...  It didn't quite
>     > work out
>
> For good reason.
>
> It's only useful to have a file-name _name_ for a thing if...  the thing
> acts
> like a file - i.e. you can plug that file-name into other places you might
> use
> a file-name (e.g. '> {foo}' or 'ed <foo>', etc, etc).
>
> There is very little in the world of networking that acts like a file. Yes,
> you can go all hammer-nail, and use read() and write() to get data back and
> forth, and think that makes it a file - but it's not.
>
> For instance, files, as far as I know, generally don't have timeout
> semantics. Can the average application that deals with a file, deal
> reasonably
> with the fact that sometimes one gets half-way through the 'file' - and
> things
> stop working?  And that's a _simple_ one.  How does a file abstraction
> match
> to a multi-cast lossy (i.e. packets may be lost) datagram group?
>
> For another major point (and the list goes on, I just can't be bothered to
> go
> through it all), there's usually all sorts of other higher-level protocol
> in
> there, so only specialized applications can make use of it anyway. Look at
> HTTP: there's specialized syntax one has to spit out to say what file you
> want, and the HTML files you get back from that can generally only be
> usefully
> used in a browser.
>

Just because an OS provides unstructured files as its primary or only
IPC primitive doesn't mean that you can't run a structured protocol
over them (after all, the IP protocol suite provides only unstructured
transports - byte streams or unconnected datagrams - to the
application layer). That's what I'm planning to do in UX/RT. Services
that don't fit into an unstructured file model will run a structured
protocol over the file transport (UX/RT will provide a
message-boundary-preserving special file type specifically because
it's easier to implement RPC-like and other structured protocols over
such a transport). And just because such services will be harder to
use with tools like ed, cat, and the like doesn't mean there aren't
other advantages to having them in the filesystem. In UX/RT, the main
advantages of the file-oriented architecture for services using
structured protocols will be the unified security model and the ease
of overriding such services with filter servers (e.g. UX/RT's fakeroot
will be a pure server rather than an unreliable LD_PRELOAD hack, and
in a similar vein, jails in UX/RT will be able to virtualize as much
or as little as desired rather than being pretty much all-or-nothing
like in a lot of other OSes).


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