| /* |
| * 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.samza.operators.functions; |
| |
| import java.io.Serializable; |
| import org.apache.samza.annotation.InterfaceStability; |
| |
| |
| /** |
| * Joins incoming messages in two streams by key. |
| * |
| * @param <K> type of the join key |
| * @param <M> type of the input message |
| * @param <JM> type of the message to join with |
| * @param <RM> type of the joined message |
| */ |
| @InterfaceStability.Unstable |
| public interface JoinFunction<K, M, JM, RM> extends InitableFunction, ClosableFunction, Serializable { |
| |
| /** |
| * Joins the provided messages and returns the joined message. |
| * |
| * @param message the input message |
| * @param otherMessage the message to join with |
| * @return the joined message |
| */ |
| RM apply(M message, JM otherMessage); |
| |
| /** |
| * Get the join key for messages in the first input stream. |
| * |
| * @param message the message in the first input stream |
| * @return the join key |
| */ |
| K getFirstKey(M message); |
| |
| /** |
| * Get the join key for messages in the second input stream. |
| * |
| * @param message the message in the second input stream |
| * @return the join key |
| */ |
| K getSecondKey(JM message); |
| |
| } |