Package ptolemy.actor

Class ConstantPublisherPort

  • All Implemented Interfaces:
    java.lang.Cloneable, Initializable, HasTypeConstraints, Typeable, Changeable, Debuggable, DebugListener, Derivable, HierarchyListener, ModelErrorHandler, MoMLExportable, Moveable, Nameable
    public class ConstantPublisherPort
extends PublisherPort
    This is a specialized output port that publishes constant data sent on the specified named channel. The tokens are "tunneled" to any instance of SubscriberPort that names the same channel. If PubSubPort.global is false (the default), then this publisher will only send to instances of SubscriberPort that are under the control of the same director. That is, it can be at a different level of the hierarchy, or in an entirely different composite actor, as long as the relevant composite actors are transparent (have no director). If PubSubPort.global is true, then the subscriber may be anywhere in the model, as long as its global parameter is also true.

    Note that this port should be used just like a PublisherPort. If you put it in an opaque composite actor, then it requires a token on the inside in order to produce its output. It will replace each token with the constant value. Similarly, if it is put into a transparent composite actor, then tokens must be sent through it. Those tokens will be replaced with the constant value. If it is put into an atomic actor, then the actor should call one of its broadcast or send methods, providing a token that will be replaced with the constant token. This pattern ensures that data dependencies work with this port just as with any other port.

    It is an error to have two instances of PublisherPort or ConstantPublisherPort using the same channel under the control of the same director. When you create a new PublisherPort or ConstantPublisherPort, by default, it has no channel name. You have to specify a channel name to use it.

    How it works: When the channel name is specified, typically during model construction, this actor causes a relation to be created in the least opaque composite actor above it in the hierarchy and links to that relation. In addition, if PubSubPort.global is set to true, it causes a port to be created in that composite, and also links that port to the relation on the inside. The relation is recorded by the opaque composite. When a SubscriberPort is preinitialized that refers to the same channel, that SubscriberPort finds the relation (by finding the least opaque composite actor above it) and links to the relation. Some of these links are "liberal links" in that they cross levels of the hierarchy.

    Since publishers are linked to subscribers, any data dependencies that the director might assume on a regular "wired" connection will also be assumed across publisher-subscriber pairs. Similarly, type constraints will propagate across publisher-subscriber pairs. That is, the type of the subscriber output will match the type of the publisher input.

    Since:
    Ptolemy II 10.0
    Version:
    $Id$
    Author:
    Edward A. Lee
    Pt.AcceptedRating:
    Red (eal)
    Pt.ProposedRating:
    Yellow (eal)

    • Field Detail

      • constantValue

        public Parameter constantValue
        The constant value to publish. This can have any type. It defaults to the integer 0.

      • numberOfTokens

        public Parameter numberOfTokens
        The number of constant tokens to publish. By default, this is UNBOUNDED, which means that there is no limit.

    • Constructor Detail

      • ConstantPublisherPort

        public ConstantPublisherPort​(ComponentEntity container,
                             java.lang.String name)
                      throws IllegalActionException,
                             NameDuplicationException
        Construct a constant publisher port with the specified name and container.
        Parameters:
        container - The container actor.
        name - The name of the port.
        Throws:
        IllegalActionException - If the port is not of an acceptable class for the container, or if the container does not implement the Actor interface.
        NameDuplicationException - If the name coincides with a port already in the container.