Multi stacks = multi processes?

Jan Schenkel janschenkel at yahoo.com
Wed Jul 31 02:50:00 EDT 2002


Hi Mike,

So far nearly all the suggestions others have made are
for building your own "send" cycles to keep everything
running within a single Revolution process.

Might I suggest a different approach? It's actually
pretty easy to have communication between several
Rev-apps under MacOS, using the IAC (Inter-Application
Communciation) calls provided within Revolution.
Specifically I'm talking about
    send to program
    request
    reply

First you would have to build one separate app per
type of process, then whenever you have a long job
ahead of you, your main program could spawn off a new
child-process and interact with it using these
commands.
If you setup "send" cycles in the child-process, you
can then see how far along it is in progress, or if
you don't need that detailed information you can
simply let it get back to you once it's finished.
The main thing you'd have to do is maintain jobID's
for easy communication, and report to the user.

So if we put this theory in practice, we get the
following cycle:

1) spawn a new child-process for a file to process
    launch fileToProcess with <childProcess>
The childProcess will get an 'odoc' appleEvent which
tells it what file to open, so add a handler for this
event to your stack script
    on appleEvent pClass, pID, pSender
      switch (pClass&pID)
      case "aevtodoc"
        request appleEvent data
        put it into theFile
        break
      default
        break
      endswitch
    end appleEvent

2) setup communication and jobID
Then the childProcess asks the mainProcess that it's
ready to proceed and would like to have a jobID
    request "jobID("&theFile&")" from program \
    <mainProcess>

3) commincation between mainProcess and childProcess
Once that has been established, we can either setup
our send cycle within the childProcess and let the
mainProcess poll the status with
    request "jobStatus" from program <childProcess>
or forego with these hassles and keep the mainProcess
up to date with our progress at regular intervals
within the process, or simply at the end with
    send "updateStatus"&&jobID"&","&jobStatus to \
    program <mainProcess>

4) cleaning up at the end
The childProcess terminates and the mainProcess can
update its screen to inform the user. In the meantime,
it could have spawned off a few other processes, and
all it would have had to do itself is minor tasks and
maintain communication with the child-processes.

Hope this helped a bit. Admittedly, I've never done
this myself, though I have in the past successfully
used the IAC-capabilities of MacOS+HyperCard to build
a client-server architecture without a full-fledged
dtabase server at the back-end.

Jan Schenkel.

"As we grow older, we grow both wiser and more foolish
at the same time."  (De Rochefoucald)

--- Mike McManus <mcmanusm at kramergraphics.com> wrote:
> I am sure this has come up before, but I can't find
> it.
> 
> I have a stack with substacks that will be handling
> a number of things 
> from watching folders, copying files and processing
> very large files(up 
> to about 300meg) None of the processes is a
> killer...under Mac OS X, OS 
> 9 is slow. But now I want to move this whole thing
> to a more hot folder 
> based system. Meaning multiple users will be putting
> multiple files into 
> folders that my app will then check, move, read and
> write.  I figure I 
> can deal with handing of the process to substack or
> stacks as required, 
> but I want them to happen simiultaniously?
> 
> What I want is to be copying at the same time a file
> is being read/wrote 
> and still keep an eye on the directories. each
> process working with  
> different files of course.  Normally Rev would not
> do that. But if I put 
> the different processes in different STACKS or
> SUBSTACKS? would I be 
> able to get this?
> 
> _______________________________________________
> use-revolution mailing list
> use-revolution at lists.runrev.com
>
http://lists.runrev.com/mailman/listinfo/use-revolution


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