Multithreaded Python FSM (Harel State Machines)

Leonard J. Reder reder at
Fri Jun 10 00:33:51 CEST 2005

Hello list,

I have been searching on the web for a while now for a specific Python 
implementation of an FSM.  More specifically what I am looking
for is a Python implementation of the so called UML Harel State Machine
notion of a state machine.  These are multi-threaded capable state
machines with hierarchical representation capability (nested
instances of state machines).  They also have a unique conditional 
trigger symbol scheme for event representation and state machine 

I have seen some great implementations of simple FSMs and some 
interesting descriptions of how generator/yeild python keywords can be 
used.  I think python has all the pieces to make a Heral implementation.

Does anyone know of a Python implementation of FSM that comes close to 
this functionality?  Any comments or recommendation for FSM packages 
that I could add this functionality to would also be welcome.  I 
certainly think someone has done something that approaches this already.

All replies are very much appreciated.  If I get enough response I will 
post a summary of findings to this group.

Thanks for reading this and please reply.


Leonard J. Reder
Jet Propulsion Laboratory
Interferometry Systems and Technology Section 383
Email: reder at
Phone (Voice): 818-354-3639
Phone (FAX): 818-354-4357
Mail Address:
Mail Stop: 171-113
4800 Oak Grove Dr.
Pasadena, CA. 91109

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