[kepler-dev] Global access of a value among all workflow actors?

[Norbert Podhorszki]

Hi Nandita,

some days ago I was also struggling with such needs (configuration 
determined at beginning influences all subworkflows; logging; 
(implicit) control flow).

My own answer for myself was:
This would be a different (second) mechanism for communication among 
actors, which is not presented by the graphics. I think, Ptolemy and 
Kepler, and any other graphical design tool can kill itself in two 
different ways:
  1. When people feel the tool too limited, developers try to add 
workarounds. This results in the extensive use of workarounds, so the 
original becomes meaningless: why to use cumbersome graphics if we can 
solve it easier?

  2. Developers resist. Tool users then go for textual tools, where 
expression is stronger.
I know one example, the P-GRADE graphical parallel programming 
environment, from my previous institute, is limited by graphics to express 
all message-passing possibilities. -> People still use MPI to write 
parallel programs.


>From other viewpoint:

1. 'Global' works as long as you are located in a shared-space 
environment, practically on one PC. Whenever, Kepler/Ptolemy will support 
execution in distributed environments, a support for global notion could 
introduce a bigger mess than that extra dozens of connections.

2. As far as I know, there is no graphical tool for shared-space concept. 
Because, how could you represent the mess, what happens in a shared-memory 
application, graphically?


I would like to think about rather graphical solutions,
  e.g. layered views, (bring to front/send to back a'la Powerpoint)
  e.g. colors/styles for connections (I would distinguish in my workflows 
data flow/control flow/configuration info/logging info)

Tim McPhillips and Bertram Ludaescher are working on the "collection 
oriented" dataflow concept, which can reduce the number of connections on 
the screen. Such an approach may you help, or not.

Best regards
Norbert
-- 

      Norbert Podhorszki
    ------------------------------------
      University of California, Davis
      Department of Computer Science
      1 Shields Ave, 2236 Kemper Hall
      Davis, CA 95616
      (530) 754-8188
      pnorbert at cs.ucdavis.edu
      ----------------------------------

On Thu, 2 Mar 2006, Nandita Mangal wrote:

>
> Hi there,
>
> Is there anyway/ possible implementaion, where given an output generated
> from an actor, can be stored in the worfklow Parameter/ other location?.
> And later on that value be used by mulitple actors on the same canvas?.
> The need for this is required to avoid messy connections b/w main and
> multiple other actors (accessing the output generated from the main
> actor) Hence a global value / global token that can be edited and
> accessed by a given workflow.
>
> Thanks,
> Chien-Yi
> Nandita Mangal.
>
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