As I peruse the RPC spec (rpc.capnp), I’m following along pretty well until I hit the ‘disembargo’ message (which my spellchecker keeps changing into ‘disembark’, but that’s another matter.)
At this point I’m only interested in Level 1 functionality, two peers, which AFAIK is as far as the implementation is gotten.Disembargo is a level 1 message, and I’m having some trouble understanding it, partly because it seems to only be relevant at levels 2+. The description starts on line 660: > # Message sent to indicate that an embargo on a recently-resolved promise > may now be lifted. > # > # Embargos are used to enforce E-order in the presence of promise > resolution. That is, if an > # application makes two calls foo() and bar() on the same capability > reference, in that order, > # the calls should be delivered in the order in which they were made. But > if foo() is called > # on a promise, and that promise happens to resolve before bar() is called, > then the two calls > # may travel different paths over the network, and thus could arrive in the > wrong order. In > # this case, the call to `bar()` must be embargoed, and a `Disembargo` > message must be sent along > # the same path as `foo()` to ensure that the `Disembargo` arrives after > `foo()`. Once the > # `Disembargo` arrives, `bar()` can then be delivered. I was following along OK until “the two calls may travel different paths over the network.” We’re at Level 1, so there is only one path, the socket between peer A and peer B. Also, in "that promise happens to resolve before bar() is called”, should that be "after bar() is called”? Because if foo resolves before, why would that make the foo call arrive after the bar call? If you have time, Kenton, I’d love to see the " Carol lives in Vat A, i.e. next to Alice. In this case, Vat A needs to send a `Disembargo` message that echos through Vat B and back…” scenario broken down step-by-step. (Or if this situation is discussed in the old erights.org site, let me know the URL; I didn’t see it when I was reading through their protocol docs.) Thanks! —Jens -- You received this message because you are subscribed to the Google Groups "Cap'n Proto" group. To unsubscribe from this group and stop receiving emails from it, send an email to capnproto+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/capnproto/E3F6C227-23BD-41E9-A4BA-A93EE4586C49%40mooseyard.com.
