QueueSinkUsage.java

/*
    BeepBeep, an event stream processor
    Copyright (C) 2008-2016 Sylvain Hall�

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package basic;

import java.util.Queue;

import ca.uqac.lif.cep.Pushable;
import ca.uqac.lif.cep.tmf.QueueSink;

/**
 * Push events into a {@link ca.uqac.lif.cep.tmf.QueueSink QueueSink}
 * processor. Graphically, the queue sink is represented as follows:
 * <p>
 * <img src="./doc-files/basic/QueueSinkUsage.png" alt="Processor graph">
 * <p>
 * Since it is a <em>sink</em>, it has no output stream.
 * <p>
 * The expected output of this program is:
 * <pre>
 * Events in the sink: [foo, bar]
 * Events in the sink: [bar, baz]
 * </pre>
 * @author Sylvain Hallé
 * @difficulty Easy
 */
public class QueueSinkUsage
{
    public static void main(String[] args)
    {
        /// Create a sink
        QueueSink sink = new QueueSink();
        // Get a reference to the sink's Pushable
        Pushable p = sink.getPushableInput();
        // Push a few events into the sink
        p.push("foo");
        p.push("bar");
        // Get a reference to the sink's queue, where events are stored
        Queue<Object> queue = sink.getQueue();
        System.out.println("Events in the sink: " + queue);
        // Events remain in the queue as long as you pop them out
        queue.remove(); // Removes the first event
        p.push("baz"); // Push another one
        System.out.println("Events in the sink: " + queue);
        ///
    }

}