Package ptolemy.actor.lib

Class Publisher

  • All Implemented Interfaces:
    java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable
    Direct Known Subclasses:
    PublisherNonStrictTest
    public class Publisher
extends TypedAtomicActor
    This actor publishes input tokens on a named channel. The tokens are "tunneled" to any instance of Subscriber that names the same channel. If global is false (the default), then this publisher will only send to instances of Subscriber 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 global is true, then the subscriber may be anywhere in the model, as long as its global parameter is also true.

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

    How it works: This actor has a hidden output port. 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 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 Subscriber is preinitialized that refers to the same channel, that Subscriber 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 5.2
    Version:
    $Id$
    Author:
    Edward A. Lee, Raymond A. Cardillo, Bert Rodiers
    Pt.AcceptedRating:
    Red (cxh)
    Pt.ProposedRating:
    Green (cxh)

    • Field Detail

      • channel

        public StringParameter channel
        The name of the channel. Subscribers that reference this same channel will receive any transmissions to this port. This is a string that defaults to empty, indicating that no channel is specified. A channel must be set before the actor executes or an exception will occur.

      • global

        public Parameter global
        Specification of whether the published data is global. If this is set to true, then a subscriber anywhere in the model that references the same channel by name will see values published by this publisher. If this is set to false (the default), then only those subscribers that are fired by the same director will see values published on this channel.

      • input

        public TypedIOPort input
        The input port. This is a multiport, allowing multiple signals to be be transmitted through the publisher channel. This base class imposes no type constraints except that the type of the input cannot be greater than the type of the output.

      • output

        public PublisherPort output
        The output port. This port is hidden and should not be directly used. By default, the type of this output is constrained to be at least that of the input. This port is hidden by default and the actor handles creating connections to it.

      • propagateNameChanges

        public Parameter propagateNameChanges
        If true, then propagate channel name changes to any Subscribers. The default value is a BooleanToken with the value false, indicating that if the channel name is changed, then the channel names of the Subscribers are not changed. If the value is true, then if the channel name is changed, the channel names of the connected Subscribers are updated.

        If the value is true, then SubscriptionAggregators that have the same regular expression as the channel name of the Publisher will be updated. However, SubscriptionAggregators usually have regular expressions as channel names, so usually the channel name of the SubscriptionAggregator will not be updated.

        Note that if a Publisher is within an Actor Oriented Class definition, then any Subscribers with the same channel name in Actor Oriented Class definitions will not be updated. This is because there is no connection between the Publisher in the Actor Oriented Class definition and the Subscriber. However, if the channel name in a Publisher in an instance of an Actor Oriented Class is updated, then the corresponding Subscribers in instances of Actor Oriented Class will be updated.