/**
* (c) Copyright 2012 WibiData, Inc.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
* Licensed 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.kiji.mapreduce.impl;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.client.Scan;
import org.kiji.annotations.ApiAudience;
/**
* An interface for Kiji mappers or bulk importers that read from HBase HTables.
*
* <p>Reading from an HTable requires knowing what subset of rows and columns should be
* read (accomplished by configuring a Scan descriptor).</p>
*
* <p>If your mapper or bulk importer uses an HTableInputFormat, you should implement this
* interface as a means of specifying the input HTable scan descriptor.</p>
*/
@ApiAudience.Private
public interface HTableReader {
/**
* Returns an HBase scan descriptor that specifies what subset of rows and cells should
* be read from the input HTable.
*
* <p>This method may return null, meaning that this instance is not really able to read
* from an HTable.</p>
*
* @param conf The job configuration.
* @return A new scan descriptor.
* @throws IOException If the scan descriptor cannot be constructed.
*/
Scan getInputHTableScan(Configuration conf) throws IOException;
}