Re: Distributed Systems Annex, data sharing between programs

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 9 Cze, 17:14, Robert A Duff <bobd...@shell01.TheWorld.com> wrote:

> Do you know about pragma Asynchronous (aspect Asynchronous in Ada 2012)?
> It causes an "RPC" to behave like a message rather than a call

Not really... It is still a call, just without the second part of it.

> So with DSA, you can loop through those thousand machines,
> and do an asynchronous "call" to each.  This just sends
> a thousand messages -- no waiting for replies, no dealing
> with failed nodes, etc.

I want to know which has failed. And I want to get responses or
rejections from those targets that got the message.

In YAMI4 I would create a container of message objects and send them
in a loop. Sending in YAMI4 is asynchronous and therefore non-
blocking, so the loop will execute in a fraction of a second. The
messages will get queued for transmission, but since their
destinations are disctinct, they will be transmitted over independent
channels. The internal mechanics is implemented in a way that allows
to deal with multiple messages in various stages of processing and
this is what will allow them to be physically transmitted in parallel.
Coming back to my application code - after the loop I would do another
loop over the same container of messages, gathering the results,
statuses, etc. I can do that, because I have a message that is a
tangible entity and that allows me to still interact with it. This is
what "asynchronous RPC" (that's an oxymoron) cannot do exactly due to
the integration with the language that is sequential in nature.

--
Maciej Sobczak * http://www.msobczak.com * http://www.inspirel.com