storm-core/src/jvm/org/apache/storm/windowing/Window.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.util.List;

/**
 * A view of events in a sliding window.
 *
 * @param <T> the type of event that this window contains. E.g. {@link org.apache.storm.tuple.Tuple}
 */
public interface Window<T> {
    /**
     * Gets the list of events in the window.
     *
     * @return the list of events in the window.
     */
    List<T> get();

    /**
     * Get the list of newly added events in the window since the last time the window was generated.
     *
     * @return the list of newly added events in the window.
     */
    List<T> getNew();

    /**
     * Get the list of events expired from the window since the last time the window was generated.
     *
     * @return the list of events expired from the window.
     */
    List<T> getExpired();
}