[kepler-dev] Building Actors

ian.brown@hsbcib.com ian.brown at hsbcib.com
Fri Oct 26 08:26:46 PDT 2007

        it sounds as though you are going through the same experience that 
I went though a few months ago. Keep at it, it's worth it in the end :)
I found that the best place to start was Ptolemy. It's much easier to 
write an actor that works in Ptolemy than it is to get one to work in 
Kepler (there's less to do in order to instantiate it). Another way to 
look at it is that as Kepler is based on Ptolemy, by starting with Ptolemy 
you're starting on a simpler platform and can move up later.

Currently I am still working in the Ptolemy virgil framework but plan to 
move to Kepler at some stage in the future. That's feasible because all my 
actors should work out of the box in Kepler.

I have also had a lot of success with the Python Script actor. It allows 
me to almost do what you describe below and because jython compiles to 
java bytecode it is pretty quick too. It's an attractive alternative to 
writing lots of custom Java actors.


"Kenneth Evans" <evans at aps.anl.gov> 
Sent by: kepler-dev-bounces at ecoinformatics.org
26/10/2007 16:09
Mail Size: 13505

"Kepler Developers" <Kepler-dev at ecoinformatics.org>

[kepler-dev] Building Actors
Investment Banking Europe - IBEU

After working on it several hours again last night, I still can?t build 
Kepler.  I?m not complaining.  It is as good a way to learn the program as 
any, and I am confident it will be fixed.
The problem is that I shouldn?t have to be building it.  While 
contributing as a developer may be feasible at some time, I only learned 
about Kepler last week and I am presently not sufficiently knowledgeable 
to contribute.  I would not like uniformed amateurs contributing to my 
projects, and I would not do that to others.
All I want to do is implement an actor.  I wrote one in about 15 min. 
(using the HelloWorld tutorial) two days ago.  I still can?t run it.
I am aware of a program, JAS3, that is developed at Stanford and is used 
by the high-energy physics community.  (You can Google it.)  This program 
has plug-ins, which are similar to actors in that they [may] consist of a 
relatively simple Java file.  They have a tree view with the plug-in on 
the left, similar to what is in Kepler.  However, in their GUI you can 
create, edit, and compile the Java program, and add it to the tree or 
modify it while in the tree.  (You can also use it from the tree, of 
course.)  This is actually not that hard to implement.
Perhaps I?ve missed something, but it seems very inconvenient to create 
and debug actors in Kepler.  If I were running an experiment using the 
Kepler workflow, I would like to be able to correct mistakes or change 
things deeper than the flow diagram on the fly during a run.
(I realize it may not be wise to be critical when you are an uninformed 
amateur, but hopefully this will be taken in the right spirit. ;-)
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