[kepler-dev] FSMDirector and wire issues

Edward A. Lee eal at eecs.berkeley.edu
Tue Sep 4 09:24:34 PDT 2007


Thanks for reporting these issues.
One resolution and one question.

At 01:03 AM 8/31/2007, ian.brown at hsbcib.com wrote:
>The issues are as follows:
>1) The wire actor in the DEDomain would appear to be broken. It has a
>parameter for an initial value but this is never used - it is stored but it
>is not used when initialising the output array. This results in a null
>pointer exception when you try to use it with true asynchronous events on
>the input. It would only work if the initial inputs arrived at the same

This actor was never finished, and shouldn't have been in
the library.  I finished it, and added a test,
so it now works, but then realized
that its behavior is essentially the same as Sampler...
I don't see a real use for it.  Am I wrong about this?

>2) The FSMDirector changes the workspace version on a transition. I have a
>DEDirector with a FSM modal model in it. In this model is another
>DEDirector. Events come in at about every 50 milliseconds and for each
>event we have on average 2 state transitions. Due to the workspace
>increment (see line 579 in FSMDirector.java) when DEDirector.fireAt() is
>next called (which is called by FSMDirector.postfire()) the entire DAG is
>rebuilt by DEDirector.getDepthOfActor().
>This obviously decimates the performance (there is more than an order of
>magnitude difference than when the state transition is not taken) and I
>don't think it should be necessary. Can someone who knows the code please
>comment - I am happy to investigate the change but would like to understand
>the background reasoning for the current implementation first.

Yes, this is completely bogus... There is a FIXME there,
which unfortunately will be a fair amount of work to fix...
I'll take this on, however, since being able to use FSM in DE
is very important (particularly for our own PTIDES work).


>As a general comment, what we're doing here is slightly different than what
>Kepler / Ptolemy was designed for. Rather then just simulation, we using it
>to run a real live system in addition to running it in simulation mode with
>historical data. I'm happy to report that so far it looks like it can do
>this and is more capable than equivalent commercial systems I have looked.
>Well done to all of the developers!
>As a last point, can I request a read access account for the Kepler source
>code please.
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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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