Re: Distributed Systems Annex, data sharing between programs

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Fri, 8 Jun 2012 14:26:55 -0700 (PDT), Maciej Sobczak wrote:

> Now, the contrary example.
> 
> You have a system with several thousand machines and you want to send
> them new configuration or something. You know the locations of those
> systems, but the little problem is that with this scale some of them
> are not working at all, some are hanging and some are overloaded and
> therefore process everything very slowly.

In our case the locations are unknown. The middleware supports discovery
and identification.

Another typical case in process automations is when there are many
thousands of process variables distributed over not so many hosts. The
variables are not well known in advance, some may be unavailable at time.
Others are optional and created dynamically on request.

Anyway, synchronous communication is not an option in any realistic process
automation setup, even if real-time. Not worth to consider. Especially
because some data distribution layers are logically and physically
unidirectional, various 1-to-N schemes.

Our middleware supports synchronous calls, but they are implemented on top
of an asynchronous layer as send/request + wait.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de