    001/*
    002 * Copyright (c) 2007-2017 Xplenty, 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  }