Hi. MarkM summarized things pretty well. Oz grew out of attempts to combine the concurrent logic programming stuff MarkM mentioned and logic programming constraint/search stuff. A few of the researchers started focussing on distributed computing and security a year or two ago. I see them once or twice a year and every time I urge them to look at E. I did just send a couple Oz researchers this message encouraging them to join in on the discussion. If a discussion does ensue please include me (I'm not on the e-lang list).
Best,
-ken
> At 01:13 PM 1/19/00 , Paul Snively wrote:
> >Folks,
> >
> >Has anyone here looked at Oz? <http://www.mozart-oz.org>
> >
> > >From their introduction:
> >
> >"In a distributed environment Oz provides language security. That is, all
> >language entities are created and passed explicitly. An application
cannot
> >forge references nor access references that have not been explicitly
given
> >to it. The underlying representation of the language entities is
> >inaccessible to the programmer. This is a consequence of having an
abstract
> >store and lexical scoping. Along with first-class procedures, these
> >concepts are essential to implement a capability-based security policy,
> >which is important in open distributed computing."
> >
> >This sure sounds like Trusty Scheme or E to me.
>
> Oz does indeed look very interesting. It seems to share these properties
> with E by virtue of common ancestry. Oz is at least closely related to
Flat
> Concurrent Prolog, and probably derived from it. As shown on
> http://www.erights.org/history/index.html , Concurrent Prolog, Actors, and
> KeyKOS all have capability nature, and together begat Joule. Most of the
> important formal properties of E, especially capability security, are
> inherited directly from Joule.
>
> The paper "Language Design and Open Systems" by Ken Kahn and myself (in
The
> Ecology of Computation, 1988) explain why Concurrent Prolog & Actors have
> capability-nature. Curiously, Concurrent Prolog was not conceived with
> security in mind, but as with the purer lambda languages, capability
nature
> was a fortuitous consequence of the formalism. Vulcan is Joule's unshown
> ancestor. It first brought together Concurrent Prolog & Actors. ("Vulcan
> == Logical Actors". Get it?) Vulcan, Joule, and Trusty Scheme were the
> first languages explicitly designed to satisfy the requirements set out in
> that paper.
>
> In any case, I skimmed their web site and couldn't find the introduction
you
> quote above, or anything else on capability security. Although they do
> distributed programming, I didn't see anything to indicate they are doing
> cryptographically-based distributed capabilities. If not, then their
above
> paragraph would not hold between mutually suspicious machines.
>
> >Anyone know more about the Mozart environment and/or the Oz language?
>
> Well, I know someone who knows more...
>
> Ken, could you clarify? Also, please feel free to forward to the Mozart
> folks you know. Thanks.
>
>
> Cheers,
> --MarkM
>
>