/**
* 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.hadoop.streaming.io;
import java.io.IOException;
import org.apache.hadoop.streaming.PipeMapRed;
/**
* Abstract base for classes that read the client's output.
*/
public abstract class OutputReader<K, V> {
/**
* Initializes the OutputReader. This method has to be called before
* calling any of the other methods.
*/
public void initialize(PipeMapRed pipeMapRed) throws IOException {
// nothing here yet, but that might change in the future
}
/**
* Read the next key/value pair outputted by the client.
* @return true iff a key/value pair was read
*/
public abstract boolean readKeyValue() throws IOException;
/**
* Returns the current key.
*/
public abstract K getCurrentKey() throws IOException;
/**
* Returns the current value.
*/
public abstract V getCurrentValue() throws IOException;
/**
* Returns the last output from the client as a String.
*/
public abstract String getLastOutput();
}