[Info-vax] message communication (VMS <> PC)

[JF Mezei]

Richard Maher wrote:

> TCPWare, Multinet, & UCX, all accept the *same* $QIO calls. Process Software
> have been at pains to maintain/introduce conformity across the IP Stacks,
> and the _BG: driver interface specifically.

Don't the commercial offering have a "emulation" layer to support the
UCX style of $QIO ? Or have they gone "native" now with this interface
being part of their core stack ?

> If you can't handle $QIO then stop programming and take up real estate.
> (Sage advice for us all)

SYS$IO does not exist outside of VMS, so using a properietary interface
is not very smart if you wish your software to exist outside of VMS.

And because SYS$QIO driver for BG does not support a timer for the read
operations, one has to write your own wrapper routines that call
SYS$SETIMR and then SYS$QIO and then a SYS$WAITEF to implement your own
timeout (and after the event flag has been set, you need to check
whether the IO or the timer completed, and then cancel the one that
didn't complete, and in the case of the IO, be able to handle the fact
that the IO then completes with a canceled status and potentially some
data in it if I remeber correctly.

In other words, it doesn't give you much of an advantage.