001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.io.compress;
020
021import java.io.IOException;
022import java.io.InputStream;
023import java.io.OutputStream;
024
025import org.apache.hadoop.classification.InterfaceAudience;
026import org.apache.hadoop.classification.InterfaceStability;
027
028/**
029 * This class encapsulates a streaming compression/decompression pair.
030 */
031@InterfaceAudience.Public
032@InterfaceStability.Evolving
033public interface CompressionCodec {
034
035  /**
036   * Create a {@link CompressionOutputStream} that will write to the given 
037   * {@link OutputStream}.
038   * 
039   * @param out the location for the final output stream
040   * @return a stream the user can write uncompressed data to have it compressed
041   * @throws IOException
042   */
043  CompressionOutputStream createOutputStream(OutputStream out) 
044  throws IOException;
045  
046  /**
047   * Create a {@link CompressionOutputStream} that will write to the given 
048   * {@link OutputStream} with the given {@link Compressor}.
049   * 
050   * @param out the location for the final output stream
051   * @param compressor compressor to use
052   * @return a stream the user can write uncompressed data to have it compressed
053   * @throws IOException
054   */
055  CompressionOutputStream createOutputStream(OutputStream out, 
056                                             Compressor compressor) 
057  throws IOException;
058
059  /**
060   * Get the type of {@link Compressor} needed by this {@link CompressionCodec}.
061   * 
062   * @return the type of compressor needed by this codec.
063   */
064  Class<? extends Compressor> getCompressorType();
065  
066  /**
067   * Create a new {@link Compressor} for use by this {@link CompressionCodec}.
068   * 
069   * @return a new compressor for use by this codec
070   */
071  Compressor createCompressor();
072  
073  /**
074   * Create a {@link CompressionInputStream} that will read from the given
075   * input stream.
076   * 
077   * @param in the stream to read compressed bytes from
078   * @return a stream to read uncompressed bytes from
079   * @throws IOException
080   */
081  CompressionInputStream createInputStream(InputStream in) throws IOException;
082  
083  /**
084   * Create a {@link CompressionInputStream} that will read from the given 
085   * {@link InputStream} with the given {@link Decompressor}.
086   * 
087   * @param in the stream to read compressed bytes from
088   * @param decompressor decompressor to use
089   * @return a stream to read uncompressed bytes from
090   * @throws IOException
091   */
092  CompressionInputStream createInputStream(InputStream in, 
093                                           Decompressor decompressor) 
094  throws IOException;
095
096
097  /**
098   * Get the type of {@link Decompressor} needed by this {@link CompressionCodec}.
099   * 
100   * @return the type of decompressor needed by this codec.
101   */
102  Class<? extends Decompressor> getDecompressorType();
103  
104  /**
105   * Create a new {@link Decompressor} for use by this {@link CompressionCodec}.
106   * 
107   * @return a new decompressor for use by this codec
108   */
109  Decompressor createDecompressor();
110  
111  /**
112   * Get the default filename extension for this kind of compression.
113   * @return the extension including the '.'
114   */
115  String getDefaultExtension();
116}