Re: [friam] What is a capability?
"Mark S. Miller" <[email protected]>
| Newsgroups | gmane.comp.capabilities.general |
|---|---|
| Message-ID | <CABHxS9j2UTGrhQZiFBsUj4y1ifCsQQTRof2zeijooC9+34uUCQ@mail.gmail.com> |
KeyKOS, including that 8-bit field, is still an ocap system. Let's call the field, as the EROS part of the family does, a "facet id". The facet id is merely an implementation convenience, playing the same role that the vtable plays in a fat pointer implementation of an object and ocap language < http://erights.org/enative/fatpointers.html>. An object is an indivisible pair of state an behavior. The rest of a KeyKOS cap indicate what state should be used, i.e, what process. But only that, in combination with the facet id, indicate what behavior should be used in response to messages. (I remember this being discussed ages ago on cap-talk and/or e-lang. If anyone could find it in the archives, that would be great.) On Thu, Jan 8, 2015 at 3:02 PM, Bill Frantz <[email protected]> wrote: > On 1/8/15 at 2:38 PM, [email protected] (Karp, Alan H) wrote: > > In KeyKOS, if I understand correctly, a capability denotes some object >> and has bits specifying which method invocations are authorized. >> > > The KeyKOS Entry capability, the most actor address like capability, > included an 8 bit field that was passed to the object as an additional > parameter. Some objects used that field as an method authorization field, > but certainly not all objects. The Record Collection was one example. > > Note that the method selector was also passed as a parameter, so some > objects used it for other purposes. > > Remember, for better or worse, KeyKOS was an extension to the hardware > architecture, not a language. > > Cheers - Bill > > ----------------------------------------------------------------------- > Bill Frantz | Concurrency is hard. 12 out | Periwinkle > (408)356-8506 | 10 programmers get it wrong. | 16345 Englewood Ave > www.pwpconsult.com | - Jeff Frantz | Los Gatos, CA 95032 > > > -- > You received this message because you are subscribed to the Google Groups > "friam" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to friam+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/[email protected] > To post to this group, send email to friam-/JYPxA39Uh5TLH3MbocFF+G/[email protected] > Visit this group at http://groups.google.com/group/friam. > For more options, visit https://groups.google.com/d/optout. > -- Cheers, --MarkM _______________________________________________ cap-talk mailing list [email protected] http://www.eros-os.org/mailman/listinfo/cap-talk