[Info-vax] VMS process communication

[Simon Clubley]

On 2022-09-13, Dave Froble <davef at tsoft-inc.com> wrote:
>
> Not arguing any of that.  All I was implying was that both sides of a 
> communication must insure a successful communication, or, it never happened.
>

Not that simple (for performance reasons).

Protocols such as TCP, ZMODEM, and Kermit (with sliding windows enabled)
are all asynchronous protocols where the delivery of data to the end user
program is decoupled from the sending of ACKs back to the transmitter.

The receiver end user program can easily have received a good amount of
data from the transmitter before the transmitter has received the ACKs
from the receiver to confirm receipt of that data.

You need something that guarantees the receiver end user program and
the sender end user program are in sync at all times ? You can do that
with a layer on top of the underlying protocol, but you will take a
serious performace hit for doing so.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.