StreamsOperation.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
 *
 *   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.streams.core;

import java.io.Serializable;

/**
 * Each step in a pipeline is a StreamsOperation.
 */
public interface StreamsOperation extends Serializable {

  /**
   * Each operation must publish an identifier.
   */
  String getId();

  /**
   * This method will be called after initialization/serialization. Initialize any non-serializable objects here.
   * @param configurationObject Any object to help intialize the operation. ie. Map, JobContext, Properties, etc. The type
   *                            will be based on where the operation is being run (ie. hadoop, storm, locally, etc.)
   */
  void prepare(Object configurationObject);

  /**
   * No guarantee that this method will ever be called.  But upon shutdown of the stream, an attempt to call this method
   * will be made.
   * Use this method to terminate connections, etc.
   */
  void cleanUp();
}