    001    /*
    002     * Copyright (c) 2007-2014 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     * &#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)
    058    public @interface SerializationToken
    059      {
    060      int[] tokens();
    061
    062      String[] classNames();
    063      }