contrib/src/main/java/org/apache/apex/malhar/contrib/mqtt/AbstractSinglePortMqttOutputOperator.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.apex.malhar.contrib.mqtt;

import com.datatorrent.api.DefaultInputPort;

/**
 * This is the base implementation for a single port MQTT output operator. 
 * Subclasses should implement the conversion of a tuple to an MQTT message.
 * <p>
 * <br>
 * Ports:<br>
 * <b>Input</b>: Can have one input port<br>
 * <b>Output</b>: no output port<br>
 * <br>
 * Properties:<br>
 * None<br>
 * <br>
 * Compile time checks:<br>
 * None<br>
 * <br>
 * Run time checks:<br>
 * None<br>
 * <br>
 * <b>Benchmarks</b>:TBD
 * </p>
 * @displayName Abstract Single Port MQTT Output
 * @category Messaging
 * @tags output operator
 * @since 0.9.3
 */
public abstract class AbstractSinglePortMqttOutputOperator<T> extends AbstractMqttOutputOperator
{
  /**
   * Users need to provide implementation of what to do when encountering a tuple to message(s) to be sent to MQTT
   * @param tuple
   */
  public abstract void processTuple(T tuple);

  /**
   * This input port receives tuples, which will be written out to MQTT.
   */
  public final transient DefaultInputPort<T> inputPort = new DefaultInputPort<T>()
  {
    @Override
    public void process(T tuple)
    {
      processTuple(tuple); // This is an abstract call
    }
  };
}