MONTHLY PROGRESS REPORT

CONTRACTOR:           University of California at Berkeley
TITLE:                Open Control Platform
REPORT PERIOD:        6/15/00 - 7/15/00
SPONSOR:              Boeing Subcontract, Air Force Research Laboratory (AFRL)
REPORT PREPARED BY:   Edward A. Lee


1.  Research Status

Our major effort during this time period was to develop a strategy for
having our Java-based Ptolemy II environment work with the OCP. We
found that the standard Java ORB that comes with JDK can't talk to TAO.
Sun never implemented an event channel interface. We began using the
Orbacus ORB, from OOC (Object Oriented Concepts, Inc.) using event
channel to publish and subscribe with second clock. Xiaojun Liu and
Sonia Sachs both got Java models interacting using the Orbacus ORB.
Xiaojun got publish/subscribe actors in Ptolemy II to interact through
the Corba event channel. He was not yet using OCP wrappers (just CORBA
event channel features), nor the real-time features of TAO.

One concern that we have is that under the current TAO implementation,
each process has to run in its own JVM, which fails to exploit the
nicest feature of java, that it is multithreaded. We suspect this will
incur a significant memory penalty, since we will have several JVMs
running, but probably not much of a speed penalty (assuming there is
enough memory to avoid swapping). The long term solution to this is to
interface Ptolemy II with ZEN, and then to recreate the OCP facilities
in Java. Douglas C. Schmidt, author of TAO, writes:

>         Work on the Java version of TAO has official begun.  It will
> implement a Java version of CORBA with all the standard features that
> TAO has.  The name of the ORB is ZEN, which is currently a
> self-recursive acronym that stands for something like "ZEN Extensible
> Net-nodes."  If you have a better expansion of the ZEN acronym please
> let us know.

On global time synchronization, Tom Henzinger's group has made great
strides in realizing a compiler for their time-driven language, and we
have created a starting point for a domain in Ptolemy II that uses
their semantics.


 Meetings
 ========

None to report.