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
024import org.apache.hadoop.classification.InterfaceAudience.LimitedPrivate;
025import org.apache.hadoop.classification.InterfaceAudience.Private;
026import org.apache.hadoop.classification.InterfaceAudience.Public;
027
028/**
029 * Annotation to inform users of how much to rely on a particular package,
030 * class or method not changing over time. Currently the stability can be
031 * {@link Stable}, {@link Evolving} or {@link Unstable}. <br>
032 * 
033 * <ul><li>All classes that are annotated with {@link Public} or
034 * {@link LimitedPrivate} must have InterfaceStability annotation. </li>
035 * <li>Classes that are {@link Private} are to be considered unstable unless
036 * a different InterfaceStability annotation states otherwise.</li>
037 * <li>Incompatible changes must not be made to classes marked as stable.</li>
038 * </ul>
039 */
040@InterfaceAudience.Public
041@InterfaceStability.Evolving
042public class InterfaceStability {
043  /**
044   * Can evolve while retaining compatibility for minor release boundaries.; 
045   * can break compatibility only at major release (ie. at m.0).
046   */
047  @Documented
048  @Retention(RetentionPolicy.RUNTIME)
049  public @interface Stable {};
050  
051  /**
052   * Evolving, but can break compatibility at minor release (i.e. m.x)
053   */
054  @Documented
055  @Retention(RetentionPolicy.RUNTIME)
056  public @interface Evolving {};
057  
058  /**
059   * No guarantee is provided as to reliability or stability across any
060   * level of release granularity.
061   */
062  @Documented
063  @Retention(RetentionPolicy.RUNTIME)
064  public @interface Unstable {};
065}