Java tutorial
/** * 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.trident.drpc; import org.apache.storm.Config; import org.apache.storm.drpc.DRPCInvocationsClient; import org.apache.storm.generated.DistributedRPCInvocations; import org.apache.storm.generated.AuthorizationException; import org.apache.storm.utils.ObjectReader; import org.apache.storm.utils.ServiceRegistry; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.lang.builder.ToStringBuilder; import org.apache.thrift.TException; import org.apache.thrift.transport.TTransportException; import org.json.simple.JSONValue; import org.json.simple.parser.ParseException; import org.apache.storm.trident.drpc.ReturnResultsReducer.ReturnResultsState; import org.apache.storm.trident.operation.MultiReducer; import org.apache.storm.trident.operation.TridentCollector; import org.apache.storm.trident.operation.TridentMultiReducerContext; import org.apache.storm.trident.tuple.TridentTuple; public class ReturnResultsReducer implements MultiReducer<ReturnResultsState> { public static class ReturnResultsState { List<TridentTuple> results = new ArrayList<>(); String returnInfo; @Override public String toString() { return ToStringBuilder.reflectionToString(this); } } boolean local; Map<String, Object> conf; Map<List, DRPCInvocationsClient> _clients = new HashMap<>(); @Override public void prepare(Map<String, Object> conf, TridentMultiReducerContext context) { this.conf = conf; local = conf.get(Config.STORM_CLUSTER_MODE).equals("local"); } @Override public ReturnResultsState init(TridentCollector collector) { return new ReturnResultsState(); } @Override public void execute(ReturnResultsState state, int streamIndex, TridentTuple input, TridentCollector collector) { if (streamIndex == 0) { state.returnInfo = input.getString(0); } else { state.results.add(input); } } @Override public void complete(ReturnResultsState state, TridentCollector collector) { // only one of the multireducers will receive the tuples if (state.returnInfo != null) { String result = JSONValue.toJSONString(state.results); Map retMap = null; try { retMap = (Map) JSONValue.parseWithException(state.returnInfo); } catch (ParseException e) { collector.reportError(e); return; } final String host = (String) retMap.get("host"); final int port = ObjectReader.getInt(retMap.get("port")); String id = (String) retMap.get("id"); DistributedRPCInvocations.Iface client; if (local) { client = (DistributedRPCInvocations.Iface) ServiceRegistry.getService(host); } else { List server = new ArrayList() { { add(host); add(port); } }; if (!_clients.containsKey(server)) { try { _clients.put(server, new DRPCInvocationsClient(conf, host, port)); } catch (TTransportException ex) { throw new RuntimeException(ex); } } client = _clients.get(server); } try { client.result(id, result); } catch (AuthorizationException aze) { collector.reportError(aze); } catch (TException e) { collector.reportError(e); } } } @Override public void cleanup() { for (DRPCInvocationsClient c : _clients.values()) { c.close(); } } }