[cap-talk] Petnames versus E-order with ocaps
clandau at macslab.com
Wed Jan 28 14:08:43 EST 2009
Karp, Alan H wrote:
> E-order guarantees the following property. If Alice sends a message
> to Carol, and then Alice sends a message to Bob containing a
> reference to Carol, and Bob uses that reference to send a message to
> Carol, Carol will receive the message from Bob after she receives the
> message from Alice. (Did I get that right, MarkM?) That ordering is
> not guaranteed if Bob sends a message to Carol using a reference not
> obtained from Alice.
> A petname is a one-to-one mapping between an object reference and a
> name binding.
Forgive me, but I have enough trouble understanding this stuff, and this
seems to be imprecise. This reminds me of the confusion of Alice in
Wonderland between objects, names, and what things are called. Do you
mean to say, a petname is a one-to-one mapping between an object
reference and a name? Which I think is the same as saying, a petname is
a one-to-one binding of an object reference to a name?
> If Bob has a reference to Carol that he calls foo, a
> reference to Carol that Bob receives from Alice will also be denoted
Those two references have different properties, so they are different
references, in other words references to different objects. So they
should have different petnames.
> Here's where the versus comes in. Bob would like to ensure that a
> message he sends to Carol arrives after any messages Alice sent to
> Carol before she sent Bob a reference to Carol. In a petname system,
> he can't do that if he had a reference to Carol before Alice sent him
> one. Is that a problem or a feature?
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