external/storm-mqtt/src/main/java/org/apache/storm/mqtt/MqttMessageMapper.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.mqtt;

import java.io.Serializable;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Values;

/**
 * Represents an object that can be converted to a Storm Tuple from an AckableMessage,
 * given a MQTT Topic Name and a byte array payload.
 */
public interface MqttMessageMapper extends Serializable {
    /**
     * Convert a `MqttMessage` to a set of Values that can be emitted as a Storm Tuple.
     *
     * @param message An MQTT Message.
     * @return Values representing a Storm Tuple.
     */
    Values toValues(MqttMessage message);

    /**
     * Returns the list of output fields this Mapper produces.
     *
     * @return the list of output fields this mapper produces.
     */
    Fields outputFields();
}