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Apache Kylin - MapReduce Engine
There is a newer version: 3.1.3
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*/

package org.apache.kylin.engine.mr;

import org.apache.kylin.cube.CubeSegment;
import org.apache.kylin.job.execution.DefaultChainedExecutable;

public interface IMROutput {

    /** Return a helper to participate in batch cubing job flow. */
    public IMRBatchCubingOutputSide getBatchCubingOutputSide(CubeSegment seg);

    /**
     * Participate the batch cubing flow as the output side. Responsible for savg
     * the cuboid output to storage (Phase 3).
     * 
     * - Phase 1: Create Flat Table
     * - Phase 2: Build Dictionary
     * - Phase 3: Build Cube
     * - Phase 4: Update Metadata & Cleanup
     */
    public interface IMRBatchCubingOutputSide {

        /**
         * Add step that saves cuboid output from HDFS to storage.
         * 
         * The cuboid output is a directory of sequence files, where key is CUBOID+D1+D2+..+Dn, 
         * value is M1+M2+..+Mm. CUBOID is 8 bytes cuboid ID; Dx is dimension value with
         * dictionary encoding; Mx is measure value serialization form.
         */
        public void addStepPhase3_BuildCube(DefaultChainedExecutable jobFlow, String cuboidRootPath);

        /** Add step that does any necessary clean up. */
        public void addStepPhase4_Cleanup(DefaultChainedExecutable jobFlow);
    }

    /** Return a helper to participate in batch merge job flow. */
    public IMRBatchMergeOutputSide getBatchMergeOutputSide(CubeSegment seg);

    /**
     * Participate the batch cubing flow as the output side. Responsible for saving
     * the cuboid output to storage (Phase 2).
     * 
     * - Phase 1: Merge Dictionary
     * - Phase 2: Merge Cube
     * - Phase 3: Update Metadata & Cleanup
     */
    public interface IMRBatchMergeOutputSide {

        /**
         * Add step that saves cuboid output from HDFS to storage.
         * 
         * The cuboid output is a directory of sequence files, where key is CUBOID+D1+D2+..+Dn, 
         * value is M1+M2+..+Mm. CUBOID is 8 bytes cuboid ID; Dx is dimension value with
         * dictionary encoding; Mx is measure value serialization form.
         */
        public void addStepPhase2_BuildCube(DefaultChainedExecutable jobFlow, String cuboidRootPath);

        /** Add step that does any necessary clean up. */
        public void addStepPhase3_Cleanup(DefaultChainedExecutable jobFlow);
    }

}