content: /**
   * 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 backtype.storm.hooks;
  
  import java.io.Serializable;
  import java.util.Map;
  
  import backtype.storm.task.WorkerTopologyContext;
  
  /**
   * An IWorkerHook represents a topology component that can be executed
   * when a worker starts, and when a worker shuts down. It can be useful
   * when you want to execute operations before topology processing starts,
   * or cleanup operations before your workers shut down.
   */
  public interface IWorkerHook extends Serializable {
      /**
       * This method is called when a worker is started
       *
       * @param stormConf The Storm configuration for this worker
       * @param context This object can be used to get information about this worker's place within the topology
       */
      void start(Map stormConf, WorkerTopologyContext context);
  
      /**
       * This method is called right before a worker shuts down
       */
      void shutdown();
  }
  