storm-client/src/jvm/org/apache/storm/topology/IComponent.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 java.io.Serializable;
import java.util.Map;

/**
 * Common methods for all possible components in a topology. This interface is used when defining topologies using the Java API.
 */
public interface IComponent extends Serializable {

    /**
     * Declare the output schema for all the streams of this topology.
     *
     * @param declarer this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream
     */
    void declareOutputFields(OutputFieldsDeclarer declarer);

    /**
     * Declare configuration specific to this component. Only a subset of the "topology.*" configs can be overridden. The component
     * configuration can be further overridden when constructing the topology using {@link TopologyBuilder}
     */
    Map<String, Object> getComponentConfiguration();

}