Coda File System

Re: Ubik and PTS issues

From: Michael Callahan <>
Date: Mon, 16 Feb 1998 03:08:47 -0500 (EST)
On Sun, 15 Feb 1998, Mark G. Hayden wrote:

> Michael Callahan wrote:
> > 
> > This is a good summary of the kind of primitives Ensemble provides.  One
> > thing, however, to bear in mind: Ensemble is written as a framework in
> > Objective Caml, a dialect of ML from INRIA in France.  So one has to think
> > through the implementation consequences of incorporating it (which are
> > more significant than those raised by starting to exploit a C library).
> Ensemble is written in Ocaml, but it compiles as a C++ library, which
> means programmers can use the C++ API without being aware of the use
> of ML in Ocaml.  

Yes, but what I was driving at was a little different: a Coda that relied
on Ensemble would be a Coda that couldn't be ported to a platform unless
Ensemble, and in particular the Ocaml toolchain, is ported first.  That's
a significant implementation issue.

> This includes performance: the Ensemble protocols
> introduce as little as 8 bytes of header and 7 usecs of latency overhead
> to the cost of an unreliable IP multicast.  This makes it the lowest
> overhead reliable group communication system currently available.
> Applications can, of course, also be written in ML.

Of course, Ensemble does wonderful things, and in fact another project
I'm working on uses it.  I think the practical issues are significant

Received on 1998-02-16 03:12:25