storm-client/src/jvm/org/apache/storm/windowing/TimestampExtractor.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.storm.windowing;

import java.io.Serializable;
import org.apache.storm.tuple.Tuple;

/**
 * Interface to be implemented for extracting timestamp from a tuple.
 */
public interface TimestampExtractor extends Serializable {
    /**
     * Return the tuple timestamp indicating the time when the event happened.
     *
     * @param tuple the tuple
     * @return the timestamp
     */
    long extractTimestamp(Tuple tuple);
}