[cap-talk] - Karp - Capabilities - tracking responsibility (Was: Bellizzomi - Users in object/capability systems (was: MLS gone bad, Lampson))

Mark Miller erights at gmail.com
Wed Nov 29 13:05:02 CST 2006


On 11/29/06, Mark Miller <erights at gmail.com> wrote:
> On 11/29/06, Karp, Alan H <alan.karp at hp.com> wrote:
> > Every system I know of uses a messaging layer that takes messages from
> > the network and forwards them to local recipients.  That layer typically
> > keeps a table that maps over-the-wire-capabilities to local references.
> > E keeps one such table per vat.
>
> Actually, an E vat keeps four tables per inter-vat connection. Put
> another way, for each inter-vat connection, the vat on each side keeps
> the four tables shown at
> <http://erights.org/elib/distrib/captp/4tables.html>. I doubt this
> difference has any bearing on the present discussion though.


I just talked to Alan and we figured out our misunderstanding. Alan
was referring to E's sturdy references and captp:// URI strings, which
together are E's "offline capabilities". For these, each E vat does
indeed maintain a single mapping table as Alan states. However, you
can't directly send a message to an offline capability, you can only
derive a live reference from one.

I thought Alan was referring to E's remote live references, to which
you can send messages. For these, they are encoded as per-connection
small numbers, as in DCCS, which are looked up in the four tables I
mentioned.


-- 
Text by me above is hereby placed in the public domain

    Cheers,
    --MarkM


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