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

/**
 * An event is a wrapper object that gets stored in the window.
 *
 * @param <T> the type of the object thats wrapped. E.g Tuple
 */
public interface Event<T> {
    /**
     * The event timestamp in millis. This could be the time when the source generated the tuple or the time when the tuple was received by
     * a bolt.
     *
     * @return the event timestamp in milliseconds.
     */
    long getTimestamp();

    /**
     * Returns the wrapped object, E.g. a tuple
     *
     * @return the wrapped object.
     */
    T get();

    /**
     * If this is a watermark event or not. Watermark events are used for tracking time while processing event based ts.
     *
     * @return true if this is a watermark event
     */
    boolean isWatermark();
}