In the Rendezvous domain in Ptolemy II, each actor executes in its own thread of control, and communication between actors is by rendezvous. If an actor is ready to send a message, it blocks until the receiving actor is ready to receive it. Similarly if an actor is ready to receive a message, it blocks until the sending actor is ready to send it.

This domain supports both conditional and multi-way rendezvous. In conditional rendezvous, an actor is willing to rendezvous with any one of several other actors. In multiway rendezvous, an actor requires rendezvous with multiple other actors at the same time. When using conditional rendezvous, the choice of which rendezvous occurs is nondeterministic, in general.

The model of computation is based on the CSP model first proposed by Hoare[1] in 1978. Rendezvous-based communication is also known as synchronous message passing, but we avoid this term to avoid confusion with the SR (synchronous/reactive) domain.


  1. Neil Smyth, John S. Davis II, Thomas Huining Feng, Mudit Goel, Edward A. Lee, Thomas M. Parks and Yang Zhao, "Process Networks and Rendezvous," a chapter from
    Claudius Ptolemaeus, Editor, "System Design, Modeling, and Simulation Using Ptolemy II",, 2014. (included in the release as $PTII/doc/books/systems/PtolemyII_DigitalV1_02.pdf)
    The models provided in this chapter are also available online.
  2. Hoare, C. A. R., "Communicating Sequential Processes," Communications of the ACM, vol. 21, no. 8, August 1978.