[kepler-dev] modeling question about producing f(A, x), f(A, y)...

[Edward A. Lee]

I would use IterateOverArray for this.
It could be less cumbersome, but attached is a model
that does it. Notice that it uses only SDFDirector.

One of our objectives with the higher-order actors (like
IterateOverArray) is to capture such design patterns in easy-to-use
ways.  We aren't quite there yet, but the attached isn't too bad...

Edward


At 11:00 AM 8/3/2007, Norbert Podhorszki wrote:
>Hi,
>
>I have no working solution for the following problem described by Bruce Char, see below. Any working idea/example would be appreciated.
>I also have the same problem currently and am craving for a good solution.
>
>Thanks
>Norbert
>
>     Norbert Podhorszki
>   ------------------------------------
>     University of California, Davis
>     Department of Computer Science
>     1 Shields Ave, 2236 Kemper Hall
>     Davis, CA 95616
>     (530) 752-5076
>     pnorbert at cs.ucdavis.edu
>     ----------------------------------
>
>---------- Forwarded message ----------
>Date: Fri, 03 Aug 2007 13:14:59 -0400
>From: Bruce Char <bchar at cs.drexel.edu>
>
>That seemed to do it.  What does this setting do?
>
>I am beginning at least to understand that I don't know how to "solve" certain kinds of situations.  Here's the latest:
>
>actor 1  issues a token, call it A.  This gets split and sent to multiple branches of the work flow as a trigger.
>One of the branches contains actor 2.  This issues one or more tokens (we don't know exactly how many ahead of time).  Call them x, y, z, ...
>
>We want to create an actor that is downstream of actors 1 and 2.  Its job is to create tokens that are a function of the output of actors 1 and 2:  f(A,x), f(A,y), ...
>
>Actor 1 in real life is the job submitter, which produces the location of the working directory, actor 2 is a filter of the file watcher.  It's going to create file conversion commands that I'll pass to ssh.
>
>I have realized that I can create actors where all input ports have equal numbers of tokens going in.  But in this case I don't have that.  If I were in the ordinary programming world I would have actor 1 set a variable v, and lower a sync barrier.  actor 2 each time it emits a token would first check that the sync barrier was down and then emit the token.  The final actor would refer to the value of v and the input from actor 2 to do its work.
>
>However, I realize I don't really know how to set a variable in Kepler!  I know how to set constants (which won't help since the value of A is unknown at
>start up time).  I know how to set expressions (which can fire the same number of times as actor 1 fires, which is once).  I can imagine that there are some
>kinds of feedback loops that would remember A and then provide it each time a token from actor 2 provides a firing signal.  I am not really sure how to set
>the latter up, but needing a feedback loop also seems more complicated than an ordinary user would want.  So I figure that there's something in Kepler that can handle this simply but I don't know what it is.
>
>Bruce
>
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------------ 
Edward A. Lee
Chair of EECS and Robert S. Pepper Distinguished Professor
231 Cory Hall, UC Berkeley, Berkeley, CA 94720-1770
phone: 510-642-0253, fax: 510-642-2845
eal at eecs.Berkeley.EDU, http://ptolemy.eecs.berkeley.edu/~eal  
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