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.hadoop.yarn.client; import java.io.IOException; import java.net.InetSocketAddress; import java.security.PrivilegedAction; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.security.UserGroupInformation; import org.apache.hadoop.yarn.ipc.YarnRPC; @InterfaceAudience.Public @InterfaceStability.Evolving @SuppressWarnings("unchecked") public class AHSProxy<T> { private static final Log LOG = LogFactory.getLog(AHSProxy.class); public static <T> T createAHSProxy(final Configuration conf, final Class<T> protocol, InetSocketAddress ahsAddress) throws IOException { LOG.info("Connecting to Application History server at " + ahsAddress); return (T) getProxy(conf, protocol, ahsAddress); } protected static <T> T getProxy(final Configuration conf, final Class<T> protocol, final InetSocketAddress rmAddress) throws IOException { return UserGroupInformation.getCurrentUser().doAs(new PrivilegedAction<T>() { @Override public T run() { return (T) YarnRPC.create(conf).getProxy(protocol, rmAddress, conf); } }); } }