Re: Is it possible to have 2 display devices in one program?

[Rich Duzenbury <rduz-midrange@xxxxxxxxxxxxxxxxxxx>]

At 08:36 PM 10/20/03, you wrote:
> I've not had very much success with the SNDBRKMSG solution.  For example can
> Bob send a break message to Alice, or must he first find out her device
> name?

Another poster alludes to using any message queue.  It seems prudent to use 
a queue tied to the user's id.




> Actually, I am not trying to communicate between programs.  All of the data
> is in the same copy of the same program, if I understand what multiple
> devices do.

_Two_ jobs can display the same data by simply reading it from the same 
source.  It doesn't have to be one program with two displays.


> It still isn't clear to me if one device can open/interrupt
> another device.

Not if the device is in use.  In order to ACQ (acquire) the device, it must 
not be signed on.  The only mechanism I'm aware of, in fact a *purpose 
built* mechanism for interrupting a job, is with a break handling program.

>   I want Alice's and Bob's screens to have identical windows
> with identical data, and have the data scroll, much the same as instant
> messaging works although this could not be feature rich like Sametime and
> other instant messaging applications.

Imagine a simple table

ConvID  11p 0
SeqNum  11p 0
FromID  10a
Message 80a

Unique Key by ConvId and SeqNum.

Both Bob & Alice can be running TALK, and as long as they both share the 
same ConvID, they would both be able to retrieve the (admittedly 
simplistic) same set of data.  In fact, any number of devices can 'see' the 
conversation as long as they have the conversation id.

The only 'interesting' tidbit is how to notify any participants in the 
conversation as soon as someone enters a new record into the 
conversation.  Any number of techniques could be used - data queues, 
sockets, probably the good old end-of-file delay.


> As I said, this has no real relevance.  I just want to have a problem to
> work through, to see if it is possible.

Good plan.  I often do the same.


Regards,
Rich