samoa-api/src/main/java/org/apache/samoa/topology/ProcessingItem.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.topology;

/**
 * Processing item interface.
 * 
 * @author severien
 * 
 */
public interface ProcessingItem extends IProcessingItem {

  /**
   * Connects this processing item in a round robin fashion. The events will be distributed evenly between the
   * instantiated processing items.
   * 
   * @param inputStream
   *          Stream to connect this processing item.
   * @return ProcessingItem
   */
  public ProcessingItem connectInputShuffleStream(Stream inputStream);

  /**
   * Connects this processing item taking the event key into account. Events will be routed to the processing item
   * according to the modulus of its key and the paralellism level. Ex.: key = 5 and paralellism = 2, 5 mod 2 = 1.
   * Processing item responsible for 1 will receive this event.
   * 
   * @param inputStream
   *          Stream to connect this processing item.
   * @return ProcessingItem
   */
  public ProcessingItem connectInputKeyStream(Stream inputStream);

  /**
   * Connects this processing item to the stream in a broadcast fashion. All processing items of this type will receive
   * copy of the original event.
   * 
   * @param inputStream
   *          Stream to connect this processing item.
   * @return ProcessingItem
   */
  public ProcessingItem connectInputAllStream(Stream inputStream);

  /**
   * Gets processing item parallelism level.
   * 
   * @return int
   */
  public int getParallelism();
}