[kepler-dev] downloadable actors

Matt Jones jones at nceas.ucsb.edu
Wed Mar 31 13:20:15 PST 2004


This is a great idea, and one that I think will be critical in a variety 
of contexts.  We plan in SEEK to have many actors that are located 
elsewhere, and users will need to be able to move the code into their 
system, or, possibly more importantly, move the actor code to a remote 
system, for execution.  Chad has been working on the ClassLoader issues 
associated with dynamically loading and reloading classes at runtime 
from within Kepler, and we've had a number of proposed ways to handle 
this.  I think one of the best examples is the way in which plugins for 
JEdit are downloaded and installed.  It is seamless for the user -- you 
should check it out.  But keep in mind that we will need to be able to 
also export code to a remote system as well.  Also, as this is an 
important area of intersection with the work Chad has already started, 
it would be nice if we could work together on it.  Have you reviewed 
Chad's code on this topic?


Xiaowen Xin wrote:
> Hi Everyone,
> Something that we'd like to implement as part of SPA/Kepler is an Actor
> Repository with some actors that we don't include as part of the normal
> distribution.  So people can go there, and download additional actors.
> What do you all think is a good mechanism for doing this?
> More specifically, we could simply distribute a tarball that includes
> the actor source code, class file, and xml configuration file, ask the
> user to unpackage it in a certain directory that's in her classpath. 
> Then, ask the user to import that configuration file.  After doing this,
> the actor will get inserted into "~/.ptolemyII/user library.xml", so the
> next time the user runs SPA/Kepler, the system will automatically load
> the actor.
> However, this method seems to be quite complicated from a user
> perspective.  It would be ideal to simply have the users download one
> file, put it in a certain directory, and the system automatically loads
> it at startup.
> Dave and I have been thinking that we could potentially distribute these
> actors as .jar files, that have the source, class file, and
> configuration file all within.  The user could put this jar file in
> ~/.ptolemyII/ and the system should automatically load it at startup.
> On the downside, the implementation of this might be somewhat involved. 
> We would need to execute something that finds all jar files in
> ~/.ptolemyII/ and create our own classloader that has the jar files in
> its classpath.  Then we would need to somehow add the newly found actors
> to the treeview at the lefthand side.
> Do you all know of any built-in mechanisms that can help do this?
> Thanks,
> Xiaowen
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Matt Jones                                     jones at nceas.ucsb.edu
http://www.nceas.ucsb.edu/    Fax: 425-920-2439    Ph: 907-789-0496
National Center for Ecological Analysis and Synthesis (NCEAS)
University of California Santa Barbara
Interested in ecological informatics? http://www.ecoinformatics.org

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