001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.classification;
019
020import java.lang.annotation.Documented;
021import java.lang.annotation.Retention;
022import java.lang.annotation.RetentionPolicy;
023
024/**
025 * Annotation to inform users of a package, class or method's intended audience.
026 */
027@InterfaceAudience.Public
028@InterfaceStability.Evolving
029public class InterfaceAudience {
030  /**
031   * Intended for use by any project or application.
032   */
033  @Documented
034  @Retention(RetentionPolicy.RUNTIME)
035  public @interface Public {};
036  
037  /**
038   * Intended only for the project(s) specified in the annotation.
039   * For example, "Common", "HDFS", "MapReduce", "ZooKeeper", "HBase".
040   */
041  @Documented
042  @Retention(RetentionPolicy.RUNTIME)
043  public @interface LimitedPrivate {
044    String[] value();
045  };
046  
047  /**
048   * Intended for use only within Hadoop itself.
049   */
050  @Documented
051  @Retention(RetentionPolicy.RUNTIME)
052  public @interface Private {};
053
054  private InterfaceAudience() {} // Audience can't exist on its own
055}