content: /* Copyright 2010, Object Management Group, Inc.
   * Copyright 2010, PrismTech, Inc.
   * Copyright 2010, Real-Time Innovations, Inc.
   * All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.omg.dds.sub;
  
  import java.util.EventListener;
  
  
  import org.omg.dds.core.event.DataAvailableEvent;
  import org.omg.dds.core.event.LivelinessChangedEvent;
  import org.omg.dds.core.event.RequestedDeadlineMissedEvent;
  import org.omg.dds.core.event.RequestedIncompatibleQosEvent;
  import org.omg.dds.core.event.SampleLostEvent;
  import org.omg.dds.core.event.SampleRejectedEvent;
  import org.omg.dds.core.event.SubscriptionMatchedEvent;
  
  
  
  /**
   * Since a {@link org.omg.dds.sub.DataReader} is a kind of {@link org.omg.dds.core.Entity}, it has the ability
   * to have an associated listener. In this case, the associated listener must
   * be of concrete type DataReaderListener.
   * <p>
   * The operation {@link #onSubscriptionMatched(SubscriptionMatchedEvent)} is
   * intended to inform the application of the discovery of {@link org.omg.dds.pub.DataWriter}
   * entities that match the DataReader. Some implementations of the service
   * may not propagate this information. In that case the DDS specification
   * does not require this listener operation to be called.
   * <p>
   * A convenience class {@link org.omg.dds.sub.DataReaderAdapter} is offered in Java 5 which has an empty implementation of all
   * listener callback functions when the application extends from this class only the used callback functions that the user wants
   * to use need to be implemented.
   * <p>
   * <b><i>Example</i></b>
   * <pre>
   * <code>
   * public class MyReaderListener extends DataReaderAdapter&lt;Foo&gt;
   * {
   *      public void onDataAvailable(DataAvailableEvent&lt;Foo&gt; status) {
   *          // Handle the incoming data here.
   *      }
   *      public void onRequestedIncompatibleQos(RequestedIncompatibleQosEvent&lt;Foo&gt; status) {
   *          // Handle the incompatibility here.
   *      }
   * }
   * //Instantiate a DataReaderListener.
   * MyReaderListener listener = new MyReaderListener();
   * // Instantiate and add the status masks.
   * Collection&lt;Class&lt;? extends Status&gt;&gt; statuses = new HashSet&lt;Class&lt;? extends Status&gt;&gt;();
   * statuses.add(DataAvailableStatus.class);
   * statuses.add(RequestedIncompatibleQosStatus.class);
   * // Create the DataReader with the listener and the bit-mask.
   * subscriber.createDataReader(fooTopic, subscriber.getDefaultDataReaderQos(), listener, statuses);
   * </code>
   * </pre>
   *
   * @param <TYPE>    The concrete type of the data that can be delivered by
   *                  the {@link org.omg.dds.sub.DataReader}.
   */
  public interface DataReaderListener<TYPE> extends EventListener {
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when the deadline
       * that the DataReader was expecting through its DeadlineQosPolicy was not respected
       * for a specific instance. The implementation may be left empty when this functionality
       * is not needed. This operation will only be called when the relevant DataReaderListener
       * is installed and enabled for the RequestedDeadlineMissedStatus.
       * <p>
       * The Data Distribution Service will provide a reference to the DataReader in the RequestedDeadlineMissedStatus object
       * in the parameter status for use by the application.
       * @param status    Contains the RequestedDeadlineMissedStatus object (this is an input to the application).
       */
      public void onRequestedDeadlineMissed(
              RequestedDeadlineMissedEvent<TYPE> status);
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when the
       * RequestedIncompatibleQosStatus changes. The implementation may be left empty when this
       * functionality is not needed. This operation will only be called when the relevant DataReaderListener
       * is installed and enabled for the RequestedIncompatibleQosStatus.
       * <p>
       * The Data Distribution Service will provide a reference to the RequestedIncompatibleQosStatus object
       * in the parameter status, for use by the application.
       * <p>
       * The application can use this operation as a callback function implementing a proper response to the
       * status change. This operation is enabled by setting the RequestedIncompatibleQosStatus in the mask
       * in the call to DataReader.set_listener. When the DataReaderListener on the DataReader is not enabled
       * for the RequestedIncompatibleQosStatus, the status change will propagate to the SubscriberListener
       * of the Subscriber(if enabled) or to the DomainParticipantListener of the DomainParticipant (if enabled).
  
       * @param status    Contains the RequestedIncompatibleQosStatus object (this is an input to the application).
       */
      public void onRequestedIncompatibleQos(
              RequestedIncompatibleQosEvent<TYPE> status);
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when a (received)
       * sample has been rejected. Samples may be rejected by the DataReader when it runs out of
       * resource_limits to store incoming samples. Usually this means that old samples need to
       * be 'consumed' (for example by 'taking' them instead of 'reading' them) to make room for
       * newly incoming samples.
       * <p>
       * The implementation may be left empty when this functionality is not needed. This operation
       * will only be called when the relevant DataReaderListener is installed and enabled for the
       * SampleRejectedStatus.
       * <p>
       * The Data Distribution Service will provide a reference to the SampleRejectedStatus object in the parameter
       * status for use by the application.
       * @param status     Contains the SampleRejectedStatus object (this is an input to the application).
       */
      public void onSampleRejected(SampleRejectedEvent<TYPE> status);
  
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when the liveliness of
       * one or more DataWriter objects that were writing instances read through this DataReader
       * has changed. In other words, some DataWriter have become "alive" or "not alive".
       * The implementation may be left empty when this functionality is not needed. This operation
       * will only be called when the relevant DataReaderListener is installed and enabled for the
       * LivelinessChangedStatus.
       * <p>
       * The Data Distribution Service will provide a reference to the
       * LivelinessChangedStatus object for use by the application.
       * @param status     Contains the LivelinessChangedStatus object (this is an input to the application).
       */
      public void onLivelinessChanged(LivelinessChangedEvent<TYPE> status);
  
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when new data is
       * available for this DataReader. The implementation may be left empty when this
       * functionality is not needed. This operation will only be called when the relevant
       * DataReaderListener is installed and enabled for the DataAvailableStatus.
       * <p>
       * The statuses DataOnReadersStatus and DataAvailableStatus will occur together. In case these status changes occur,
       * the Data Distribution Service will look for an attached and activated SubscriberListener
       * or DomainParticipantListener (in that order) for the DataOnReadersStatus. In case the
       * DataOnReadersStatus can not be handled, the Data Distribution Service will look for an
       * attached and activated DataReaderListener, SubscriberListener or DomainParticipantListener
       * for the DataAvailableStatus (in that order).
       * <p>
       * Note that if onDataOnReaders is called, then the Data Distribution Service will not try to
       * call onDataAvailable, however, the application can force a call to the DataReader objects
       * that have data by means of the notifyDatareaders operation.
       *
       * @param status    Contains the DataAvailableStatus object (this is an input to the application).
       */
      public void onDataAvailable(DataAvailableEvent<TYPE> status);
  
      /**
       * This operation  is called by the Data Distribution Service when a new match
       * has been discovered for the current subscription, or when an existing match
       * has ceased to exist.
       * <p>
       * Usually this means that a new DataWriter that matches the Topic and that has compatible
       * Qos as the current DataReader has either been discovered, or that a previously discovered DataWriter
       * has ceased to be matched to the current DataReader. A DataWriter may cease to
       * match when it gets deleted, when it changes its Qos to a value that is incompatible
       * with the current DataReader or when either the DataReader or the DataWriter
       * has chosen to put its matching counterpart on its ignore-list using the
       * ignoreSubscription or ignorePublication operations.
       * <p>
       * The implementation of this Listener operation may be left empty when this
       * functionality is not needed: it will only be called when the relevant
       * DataReaderListener is installed and enabled for the SubscriptionMatchedStatus
       * @param status    Contains the SubscriptionMatchedStatus object (this is an input to the application).
       */
      public void onSubscriptionMatched(SubscriptionMatchedEvent<TYPE> status);
      /**
       * This operation is the external operation (interface, which must be implemented by
       * the application) that is called by the Data Distribution Service when a sample is lost and this
       * is detected.
       * <p>
       * The implementation may be left empty when this functionality is not needed. This operation
       * will only be called when the relevant DataReaderListener is installed and enabled for the
       * SampleLostStatus.
       * <p>
       * The Data Distribution Service will provide a reference to the SampleLostStatus object
       * for use by the application.
       * @param status     Contains the SampleLostStatus object (this is an input to the application).
       */
      public void onSampleLost(SampleLostEvent<TYPE> status);
  }
  