| /** |
| * 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.heron.streamlet.impl.operators; |
| |
| import java.util.Map; |
| |
| import org.apache.heron.api.bolt.BaseRichBolt; |
| import org.apache.heron.api.bolt.OutputCollector; |
| import org.apache.heron.api.topology.OutputFieldsDeclarer; |
| import org.apache.heron.api.topology.TopologyContext; |
| import org.apache.heron.api.tuple.Fields; |
| import org.apache.heron.streamlet.IStreamletRichOperator; |
| |
| /** |
| * The Bolt interface that other operators of the streamlet packages extend. |
| * The only common stuff amongst all of them is the output streams |
| */ |
| public abstract class StreamletOperator<R, T> |
| extends BaseRichBolt |
| implements IStreamletRichOperator<R, T> { |
| private static final long serialVersionUID = 8524238140745238942L; |
| protected static final String OUTPUT_FIELD_NAME = "output"; |
| |
| protected OutputCollector collector; |
| |
| @SuppressWarnings("rawtypes") |
| @Override |
| public void prepare(Map<String, Object> map, |
| TopologyContext topologyContext, |
| OutputCollector outputCollector) { |
| collector = outputCollector; |
| } |
| |
| /** |
| * The operators implementing streamlet functionality have some properties. |
| * 1. They all output only one stream |
| * 2. They should be able to consume each other's output |
| * This imply that the output stream should be named same for all of them. |
| */ |
| @Override |
| public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) { |
| outputFieldsDeclarer.declare(new Fields(OUTPUT_FIELD_NAME)); |
| } |
| } |