001 /* 002 * Copyright (c) 2007-2015 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 */ 020 021 package cascading.tuple.hadoop; 022 023 import java.lang.annotation.ElementType; 024 import java.lang.annotation.Retention; 025 import java.lang.annotation.RetentionPolicy; 026 import 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 * @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) 058 public @interface SerializationToken 059 { 060 int[] tokens(); 061 062 String[] classNames(); 063 }