001/*
002 * Copyright (c) 2007-2016 Concurrent, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.tuple.hadoop;
022
023import java.lang.annotation.ElementType;
024import java.lang.annotation.Retention;
025import java.lang.annotation.RetentionPolicy;
026import java.lang.annotation.Target;
027
028/**
029 * Annotation SerializationToken enables {@link cascading.tuple.io.TupleInputStream} and {@link cascading.tuple.io.TupleOutputStream}
030 * to substitute Integer values for a class name when writing out nested objects inside a {@link cascading.tuple.Tuple}.
031 * <p/>
032 * To use, add this annotation to any custom Hadoop {@link org.apache.hadoop.io.serializer.Serialization} implementation.
033 * <p/>
034 * For example:<br/>
035 * <pre>
036 * &#64;SerializationToken(tokens={222, 223}, classNames = {"example.PersonObject", "example.SiteObject"})
037 * public class MySerialization implements org.apache.hadoop.io.serializer.Serialization
038 * {
039 * public MySerialization()
040 * {
041 * ...
042 * }
043 * ...
044 * }
045 * </pre>
046 * <p/>
047 * The SerializationToken annotation allows for multiple token to className mappings, since a Serialization implementation may
048 * {@link org.apache.hadoop.io.serializer.Serialization#accept(Class)} more than one class.
049 * <p/>
050 * Note that the token integer value must be 128 or greater to save room for internal types.
051 *
052 * @see cascading.tuple.io.TupleInputStream
053 * @see cascading.tuple.io.TupleOutputStream
054 * @see TupleSerialization
055 */
056@Retention(RetentionPolicy.RUNTIME)
057@Target(ElementType.TYPE)
058public @interface SerializationToken
059  {
060  int[] tokens();
061
062  String[] classNames();
063  }