| /** |
| * 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.lib; |
| |
| import java.io.IOException; |
| import java.nio.charset.Charset; |
| import java.util.List; |
| |
| import org.apache.zookeeper.CreateMode; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.WatchedEvent; |
| import org.apache.zookeeper.Watcher; |
| import org.apache.zookeeper.ZooDefs; |
| import org.apache.zookeeper.ZooKeeper; |
| import org.apache.zookeeper.data.Stat; |
| |
| /** ZK Registration Library |
| * currently does not use any authorization |
| */ |
| public class ZKClient { |
| private ZooKeeper zkClient; |
| |
| /** |
| * the zookeeper client library to |
| * talk to zookeeper |
| * @param string the host |
| * @throws IOException |
| */ |
| public ZKClient(String string) throws IOException { |
| zkClient = new ZooKeeper(string, 30000, new ZKWatcher()); |
| } |
| |
| /** |
| * register the service to a specific path |
| * @param path the path in zookeeper namespace to register to |
| * @param data the data that is part of this registration |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public void registerService(String path, String data) throws |
| IOException, InterruptedException { |
| try { |
| zkClient.create(path, data.getBytes(Charset.forName("UTF-8")), |
| ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); |
| } catch(KeeperException ke) { |
| throw new IOException(ke); |
| } |
| } |
| |
| /** |
| * unregister the service. |
| * @param path the path at which the service was registered |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public void unregisterService(String path) throws IOException, |
| InterruptedException { |
| try { |
| zkClient.delete(path, -1); |
| } catch(KeeperException ke) { |
| throw new IOException(ke); |
| } |
| } |
| |
| /** |
| * list the services registered under a path |
| * @param path the path under which services are |
| * registered |
| * @return the list of names of services registered |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public List<String> listServices(String path) throws IOException, |
| InterruptedException { |
| List<String> children = null; |
| try { |
| children = zkClient.getChildren(path, false); |
| } catch(KeeperException ke) { |
| throw new IOException(ke); |
| } |
| return children; |
| } |
| |
| /** |
| * get data published by the service at the registration address |
| * @param path the path where the service is registered |
| * @return the data of the registered service |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public String getServiceData(String path) throws IOException, |
| InterruptedException { |
| String data; |
| try { |
| Stat stat = new Stat(); |
| byte[] byteData = zkClient.getData(path, false, stat); |
| data = new String(byteData, Charset.forName("UTF-8")); |
| } catch(KeeperException ke) { |
| throw new IOException(ke); |
| } |
| return data; |
| } |
| |
| |
| /** |
| * a watcher class that handles what events from |
| * zookeeper. |
| * |
| */ |
| private static class ZKWatcher implements Watcher { |
| |
| @Override |
| public void process(WatchedEvent arg0) { |
| |
| } |
| |
| } |
| } |