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.nifi.cluster.coordination.node; import java.io.IOException; import java.net.InetSocketAddress; import org.apache.commons.lang3.StringUtils; import org.apache.nifi.cluster.exception.NoClusterCoordinatorException; import org.apache.nifi.cluster.protocol.AbstractNodeProtocolSender; import org.apache.nifi.cluster.protocol.ProtocolContext; import org.apache.nifi.cluster.protocol.ProtocolException; import org.apache.nifi.cluster.protocol.message.ProtocolMessage; import org.apache.nifi.controller.leader.election.LeaderElectionManager; import org.apache.nifi.io.socket.SocketConfiguration; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class LeaderElectionNodeProtocolSender extends AbstractNodeProtocolSender { private static final Logger logger = LoggerFactory.getLogger(LeaderElectionNodeProtocolSender.class); private final LeaderElectionManager electionManager; public LeaderElectionNodeProtocolSender(final SocketConfiguration socketConfiguration, final ProtocolContext<ProtocolMessage> protocolContext, final LeaderElectionManager electionManager) { super(socketConfiguration, protocolContext); this.electionManager = electionManager; } @Override protected InetSocketAddress getServiceAddress() throws IOException { final String address = electionManager.getLeader(ClusterRoles.CLUSTER_COORDINATOR); if (StringUtils.isEmpty(address)) { throw new NoClusterCoordinatorException( "No node has yet been elected Cluster Coordinator. Cannot establish connection to cluster yet."); } final String[] splits = address.split(":"); if (splits.length != 2) { final String message = String.format( "Attempted to determine Cluster Coordinator address. Zookeeper indicates " + "that address is %s, but this is not in the expected format of <hostname>:<port>", address); logger.error(message); throw new ProtocolException(message); } logger.info( "Determined that Cluster Coordinator is located at {}; will use this address for sending heartbeat messages", address); final String hostname = splits[0]; final int port; try { port = Integer.parseInt(splits[1]); if (port < 1 || port > 65535) { throw new NumberFormatException("Port must be in the range of 1 - 65535 but got " + port); } } catch (final NumberFormatException nfe) { final String message = String .format("Attempted to determine Cluster Coordinator address. Zookeeper indicates " + "that address is %s, but the port is not a valid port number", address); logger.error(message); throw new ProtocolException(message); } final InetSocketAddress socketAddress = InetSocketAddress.createUnresolved(hostname, port); return socketAddress; } }