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 storm.trident.operation;
  
  import java.io.Serializable;
  import java.util.Map;
  
  /**
   * Parent interface for Trident `Filter`s and `Function`s.
   *
   * `Operation` defines two lifecycle methods for Trident components. The `prepare()` method is called once when the
   * `Operation` is first initialized. The `cleanup()` method is called in local mode when the local cluster is
   * being shut down. In distributed mode, the `cleanup()` method is not guaranteed to be called in every situation, but
   * Storm will make a best effort call `cleanup()` whenever possible.
   */
  public interface Operation extends Serializable {
      /**
       * Called when the `Operation` is first initialized.
       * @param conf the Storm configuration map
       * @param context the operation context which provides information such as the number of partitions in the stream,
       *                and the current partition index. It also provides methods for registering operation-specific
       *                metrics.
       * @see org.apache.storm.trident.operation.TridentOperationContext
       */
      void prepare(Map conf, TridentOperationContext context);
  
      /**
       * When running in local mode, called when the local cluster is being shut down.
       */
      void cleanup();
  }
  