library/src/main/java/org/apache/apex/malhar/lib/window/ControlTuple.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.lib.window;

import org.apache.hadoop.classification.InterfaceStability;

/**
 * Control tuple interface.
 * TODO: This should be removed or moved to Apex Core when Apex Core has native support for custom control tuples.
 *
 * @since 3.5.0
 */
@InterfaceStability.Evolving
public interface ControlTuple
{
  /**
   * Watermark control tuple
   */
  interface Watermark extends ControlTuple
  {
    /**
     * Gets the timestamp associated with this watermark
     *
     * @return
     */
    long getTimestamp();
  }
}