[cap-talk] Petnames versus E-order with ocaps

[Karp, Alan H]

Charles Landau wrote:
> 
> In different vats, Bob's old reference will deliver messages to Carol
> right away, while his new reference will wait until Alice's previous
> messages have arrived. Would you agree this difference requires the two
> references to be different?

E uses lambda names, so Bob does distinguish his various references to Carol.  My question is what implications that has for a different system that uses petnames.  We can't let Bob's messages to Carol go through immediately, because that violates E-order.  We can't make all of Bob's messages to Carol wait for Alice's message to arrive, because that allows a malicious vat to block another vat's independent requests.  The issue is that a petname system can't distinguish these two cases, which appears to mean that the ordering guarantees must be weaker.
> 
> In the same vat, even if the references are identical and are
> associated
> with the same petname, Bob does not have a problem ensuring the order
> of
> his messages to Carol relative to Alice's messages.
>
Bill Frantz just answered my question for a single vat.  There is only one queue, and the messages are delivered in the order they are inserted into the queue.  Since there's only one thread per vat, there is no ambiguity.

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Alan Karp
Principal Scientist
Virus Safe Computing Initiative
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