Any number of instances of Subscriber can subscribe to the same channel.
This actor actually has a hidden input port that is connected
to the publisher via hidden "liberal links" (links that are
allowed to cross levels of the hierarchy). Consequently,
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.
@author Edward A. Lee, Raymond A. Cardillo, Bert Rodiers
@version $Id: Subscriber.java 70402 2014-10-23 00:52:20Z cxh $
@since Ptolemy II 5.2
@Pt.ProposedRating Green (cxh)
@Pt.AcceptedRating Red (cxh)
*/
public class Subscriber extends TypedAtomicActor {
/** Construct a subscriber with the specified container and name.
* @param container The container actor.
* @param name The name of the actor.
* @exception IllegalActionException If the actor is not of an acceptable
* class for the container.
* @exception NameDuplicationException If the name coincides with
* an actor already in the container.
*/
public Subscriber(CompositeEntity container, String name)
throws IllegalActionException, NameDuplicationException {
// Set this up as input port.
super(container, name);
channel = new StringParameter(this, "channel");
channel.setExpression("channel1");
_createInputPort();
input.setMultiport(true);
output = new TypedIOPort(this, "output", false, true);
output.setMultiport(true);
// We only have constraints from the publisher on the subscriber
// and the output of the subscriber and not the other way around
// to not break any existing models.
output.setWidthEquals(input, false);
new Parameter(input, "_hide", BooleanToken.TRUE);
global = new Parameter(this, "global");
global.setExpression("false");
global.setTypeEquals(BaseType.BOOLEAN);
// Refer the parameters of the input port to those of
// this actor.
input.channel.setExpression("$channel");
input.global.setExpression("global");
output.setTypeAtLeast(input);
}
///////////////////////////////////////////////////////////////////
//// ports and parameters ////
/** 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 "channel1".
*/
public StringParameter channel;
/** Specification of whether the data is subscribed globally.
* If this is set to true, then this subscriber will see values
* published by a publisher anywhere in the model references the same
* channel by name. If this is set to false (the default), then only
* values published by the publisher that are fired by the same
* director are seen by this subscriber.
*/
public Parameter global;
/** The input port. This port is hidden and should not be
* directly used. This base class imposes no type constraints except
* that the type of the input cannot be greater than the type of the
* output.
*/
public SubscriberPort input;
/** The output port. This is a multiport. If the corresponding
* publisher has multiple input signals, then those multiple signals
* will appear on this output port.
* 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.
*/
public TypedIOPort output;
///////////////////////////////////////////////////////////////////
//// public methods ////
/** Clone the actor into the specified workspace.
* @param workspace The workspace for the new object.
* @return A new actor.
* @exception CloneNotSupportedException If a derived class contains
* an attribute that cannot be cloned.
*/
@Override
public Object clone(Workspace workspace) throws CloneNotSupportedException {
Subscriber newObject = (Subscriber) super.clone(workspace);
// We only have constraints from the publisher on the subscriber
// and the output of the subscriber and not the other way around
// to not break any existing models.
newObject.output.setWidthEquals(newObject.input, false);
newObject.output.setTypeAtLeast(newObject.input);
return newObject;
}
/** Read at most one input token from each input
* channel and send it to the output.
* @exception IllegalActionException If there is no director, or
* if there is no input connection.
*/
@Override
public void fire() throws IllegalActionException {
super.fire();
int width = input.getWidth();
if (width == 0) {
channel.validate();
throw new IllegalActionException(this,
"Subscriber could not find a matching Publisher "
+ "with channel \"" + channel.stringValue() + "\"");
}
for (int i = 0; i < width; i++) {
if (input.hasToken(i)) {
Token token = input.get(i);
if (i < output.getWidth()) {
output.send(i, token);
}
}
}
}
/** Return a Set of Publishers that are connected to this Subscriber.
* @return A Set of Publishers that are connected to this Subscriber.
* @exception KernelException If thrown when a Manager is added to
* the top level or if preinitialize() fails.
*/
public Set