Distributed Modeling and Design in Ptolemy II
John S. Davis II, Jie Liu, Xiaojun Liu, Sonia Sachs, UC Berkeley
davisjs@us.ibm.com, liuj@eecs.berkeley.edu, liuxj@eecs.berkeley.edu, ssachs@eecs.berkeley.edu

Network-integrated computing architectures offer facilities for federated collaboration between physically separate components and users. Distribution can improve robustness, simplify system architecture by allowing on-site processing, and improve security and confidentiality by avoiding transport of unnecessary data. It also facilities exploitation of specialized hardware, and its intrinsically parallel nature offers the promise of improved execution speeds.

Design tools can themselves be distributed to achieve these benefits, or they can incorporate facilities for effectively designing distributed applications. Although this project addresses both problems, the emphasis is on the second.

The Common Object Request Broker Architecture (CORBA) is a specification for distributed software systems that allows software objects to communicate with one another independent of their implementation language. We are exploring the use of CORBA to add distributed capabilities to the Ptolemy II infrastructure. In addition, we are considering methods for using Ptolemy II to design and deploy distributed systems. Ptolemy II is a design environment for hierarchical, heterogeneous specification of component-based systems.

In Ptolemy II, we have demonstrated importing a remote model as a component of a larger model, executing the model in a distributed fashion over a network. Current work includes the definition of a distributed software architecture for such distributed modeling. Future work includes introducing real-time support, an developing support for an event-notification style of interaction.

A major application of this work is the open control platform (OCP), which we are developing collaboratively with Boeing and Georgia Tech. The OCP is a distributed component architecture for embedded control systems, particularly in the area of avionics.