samoa-api/src/main/java/org/apache/samoa/streams/fs/FileStreamSource.java

/*
 * 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.samoa.streams.fs;

import java.io.InputStream;
import java.io.IOException;
import java.io.Serializable;

/**
 * An interface for FileStream's source (Local FS, HDFS,...)
 * 
 * @author Casey
 */
public interface FileStreamSource extends Serializable {

  /**
   * Init the source with file/directory path and file extension
   * 
   * @param path
   *          File or directory path
   * @param ext
   *          File extension to be used to filter files in a directory. If null, all files in the directory are
   *          accepted.
   */
  public void init(String path, String ext);

  /**
   * Reset the source
   */
  public void reset() throws IOException;

  /**
   * Retrieve InputStream for next file. This method will return null if we are at the last file in the list.
   * 
   * @return InputStream for next file in the list
   */
  public InputStream getNextInputStream();

  /**
   * Retrieve InputStream for current file. The "current pointer" is moved forward with getNextInputStream method. So if
   * there was no invocation of getNextInputStream, this method will return null.
   * 
   * @return InputStream for current file in the list
   */
  public InputStream getCurrentInputStream();
}