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

[Charles Landau]

Karp, Alan H wrote:
> 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.  

You are asking about a hypothetical system that uses petnames. The 
answer is in the details of that system.

I imagine a system in which a reference coming into an object (such as 
Bob) is (efficiently) compared (using some form of EQ) with all existing 
references in the object. If there is a match, the system says "here is 
a reference that you know as foo". If there is no match, a new unique 
petname is somehow generated for the incoming reference.

 > 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.

The two references Bob has to Carol (old and new) are different (see 
above), so the petname system I'm imagining must give them different 
petnames.