[kepler-dev] starting an Actor IO package

Tristan King tristan.king at jcu.edu.au
Wed Jul 2 21:42:28 PDT 2008

I've started doing a bit of work on building an actor IO package (

The purpose of this is to provide user input and output for actors so that
the actors themselves don't have to be responsible for how they get user
input, or how output is displayed. This will help to build actors that are
useable in gui and headless environments without having to have modified
actors for each situation.

I've built a simple prototype which uses an IO factory which is embedded in
the Manager (since all actors can get access to the manager which controls
them). When an actor requires an IO "device" it makes a request to the IO
factory which returns an instance of the desired "device". For example, the
Display actor requests a Text-based output device. This device implements a
standard text based output device interface which has a write(String)
function, and all the Display actor has to do is "write" the text to the
device which handles how to display it. I've used spring to instantiate the
correct IOFactory so that in the case of vergil, each manager is loaded with
a ptolemy.vergil.io.VergilIOFactory and if vergil is not used the manager
defaults to a ptolemy.actor.io.HeadlessIOFactory.

My work is currently stored in my ptII git mirror, in a branch which has
been converted for maven compilation.
If you want to clone the whole repository here are the git commands to clone
the repository and to get to the branch (this will take a while):

git clone git://git.hpc.jcu.edu.au/jc124742/ptII.git
git checkout -b actorio origin/actorio

or you can download the current snapshot of the branch (which is about 35mb)
you can then run it by doing:

mvn compile # compiles the code, may take a while the first time while maven
sorts out it's dependencies
mvn exec:exec # starts vergil

then fire up any workflow while uses a Display actor. Note that i'm rubbish
with swing and some of the window placing/sizing functionality has been
removed to facilitate the separation of the actor from the visualisation, so
the display window isn't nearly as good as the old one. If you start the
workflow using MoMLSimpleApplication (i.e:

mvn compile
java -cp
ptolemy.actor.gui.MoMLSimpleApplication ../test.xml

) it will print the output of any Display actors to the console.

If other people want to work on this, I will create a new branch for it on
the ptolemy II svn (it requires a few changes to the core of ptolemy so i'm
not gonna commit it to the trunk) and put it there in makefile building

So, is anyone else interested in this? I think it's a key component in
making kepler available in multiple environments. But it's a big change,
much too big to be left up to one person. I would feel a lot more
comfortable with a bunch of people telling me my ideas and designs are
rubbish and help me build a good system rather than to build something that
no one but me wants to use.

Things that need to be done:
* My factory idea and prototype architecture needs to be criticised.
* Types of "devices" need to be defined (i.e. text output, image output,
file output, graph output, etc)
* IO Factory and device interfaces need to be defined.
* Existing actors need to be modified to use the factory.
* standard factory implementations need to be written (i.e. I'm rubbish at
swing and thus someone else should do the vergil factory).

Comments? Ideas? Criticisms?

Tristan King
Research Officer,
eResearch Centre
James Cook University, Townsville Qld 4811

Phone: +61747816902
E-mail: tristan.king at jcu.edu.au www: http://eresearch.jcu.edu.au
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