storm-core/src/jvm/org/apache/storm/topology/IStatefulBolt.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.storm.topology;

import org.apache.storm.state.State;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.tuple.Tuple;

import java.util.Map;

/**
 * A bolt abstraction for supporting stateful computation. The state of the bolt is
 * periodically checkpointed.
 *
 * <p>The framework provides at-least once guarantee for the
 * state updates. The stateful bolts are expected to anchor the tuples while emitting
 * and ack the input tuples once its processed.</p>
 */
public interface IStatefulBolt<T extends State> extends IStatefulComponent<T> {
    /**
     * @see org.apache.storm.task.IBolt#prepare(Map, TopologyContext, OutputCollector)
     */
    void prepare(Map stormConf, TopologyContext context, OutputCollector collector);
    /**
     * @see org.apache.storm.task.IBolt#execute(Tuple)
     */
    void execute(Tuple input);
    /**
     * @see org.apache.storm.task.IBolt#cleanup()
     */
    void cleanup();
}