Examples of org.apache.zookeeper.ZooKeeper

org.apache.zookeeper.ZooKeeper
This is the main class of ZooKeeper client library. To use a ZooKeeper service, an application must first instantiate an object of ZooKeeper class. All the iterations will be done by calling the methods of ZooKeeper class.
Once a connection to a server is established, a session ID is assigned to the client. The client will send heart beats to the server periodically to keep the session valid.
The application can call ZooKeeper APIs through a client as long as the session ID of the client remains valid.
If for some reason, the client fails to send heart beats to the server for a prolonged period of time (exceeding the sessionTimeout value, for instance), the server will expire the session, and the session ID will become invalid. The client object will no longer be usable. To make ZooKeeper API calls, the application must create a new client object.
If the ZooKeeper server the client currently connects to fails or otherwise does not respond, the client will automatically try to connect to another server before its session ID expires. If successful, the application can continue to use the client.
Some successful ZooKeeper API calls can leave watches on the "data nodes" in the ZooKeeper server. Other successful ZooKeeper API calls can trigger those watches. Once a watch is triggered, an event will be delivered to the client which left the watch at the first place. Each watch can be triggered only once. Thus, up to one event will be delivered to a client for every watch it leaves.
A client needs an object of a class implementing Watcher interface for processing the events delivered to the client. When a client drops current connection and re-connects to a server, all the existing watches are considered as being triggered but the undelivered events are lost. To emulate this, the client will generate a special event to tell the event handler a connection has been dropped. This special event has type EventNone and state sKeeperStateDisconnected.


public class BasicDemo1 {


    public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
        // 创建一个与服务器的连接
        ZooKeeper zk = new ZooKeeper("192.168.1.201:2181", 60000, new Watcher() {
            // 监控所有被触发的事件
            public void process(WatchedEvent event) {
                System.out.println("EVENT:" + event.getType());
            }
        });


        // 查看根节点
        System.out.println("ls / => " + zk.getChildren("/", true));


        // 创建一个目录节点
        if (zk.exists("/node", true) == null) {
            zk.create("/node", "conan".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            System.out.println("create /node conan");
            // 查看/node节点数据
            System.out.println("get /node => " + new String(zk.getData("/node", false, null)));
            // 查看根节点
            System.out.println("ls / => " + zk.getChildren("/", true));
        }


        // 创建一个子目录节点
        if (zk.exists("/node/sub1", true) == null) {
            zk.create("/node/sub1", "sub1".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            System.out.println("create /node/sub1 sub1");
            // 查看node节点
            System.out.println("ls /node => " + zk.getChildren("/node", true));
        }


        // 修改节点数据
        if (zk.exists("/node", true) != null) {
            zk.setData("/node", "changed".getBytes(), -1);
            // 查看/node节点数据
            System.out.println("get /node => " + new String(zk.getData("/node", false, null)));
        }


        // 删除节点
        if (zk.exists("/node/sub1", true) != null) {
            zk.delete("/node/sub1", -1);
            zk.delete("/node", -1);
            // 查看根节点
            System.out.println("ls / => " + zk.getChildren("/", true));
        }


        // 关闭连接
        zk.close();
    }

View Full Code Here


  private ServerWatcher modelWatcher = new ServerWatcher();


  public Server(int port) throws TTransportException, IOException,
      InterruptedException, KeeperException {
    zk = new ZooKeeper("localhost", 2181, new Watcher() {
      @Override
      public void process(WatchedEvent watchedEvent) {
        // ignore
      }
    });

View Full Code Here

     */
    @Override
    public void process(WatchedEvent watchedEvent) {
      if (zk == null) {
        try {
          zk = new ZooKeeper("localhost", 2181, null);
        } catch (IOException e) {
          zk = null;
          return;
        }
      }

View Full Code Here

    "talk.politics.mideast",
    "talk.politics.misc",
    "talk.religion.misc");


  public static void main(String[] args) throws TException, IOException, InterruptedException, KeeperException {
    ZooKeeper zk = new ZooKeeper("localhost", 2181, new Watcher() {
      @Override
      public void process(WatchedEvent watchedEvent) {
        // ignore
      }
    });
    List<String> servers = zk.getChildren(Server.ZK_CURRENT_SERVERS, false, null);
    if (servers.size() == 0) {
      throw new IllegalStateException("No servers to query");
    }
    String hostname = servers.get(new Random().nextInt(servers.size()));
    System.out.printf("host = %s\n", hostname);

View Full Code Here

    protected ZookeeperSession(final String connectString, final int sessionTimeout) throws IOException
    {
        this.connectString = connectString;
        this.sessionTimeout = sessionTimeout;
        this.zkref = new AtomicReference<ZooKeeper>();
        final ZooKeeper newZk = makeZooKeeperClient(connectString, sessionTimeout);
        if (newZk != null) setNewZookeeper(newZk);
    }

View Full Code Here

        if (logger.isTraceEnabled()) logger.trace("Disrupting Zookeeper session by closing the session.");
        if (zkref != null)
        {
            try
            {
                final ZooKeeper cur = zkref.get();
                cur.close();
            } catch (final Throwable th)
            {
                logger.error("Failed disrupting ZookeeperSession", th);
            }
        }

View Full Code Here

     */
    protected ZooKeeper makeZooKeeperClient(final String connectString, final int sessionTimeout) throws IOException
    {
        if (logger.isTraceEnabled()) logger.trace("creating new ZooKeeper client connection from scratch.");


        return new ZooKeeper(connectString, sessionTimeout, new ZkWatcher());
    }

View Full Code Here

                {
                    registeredWatchers.add(wp);
                }
            }


            final ZooKeeper cur = zkref.get();
            try
            {
                return callee.call(cur, path, wp, userdata);
            } catch (final KeeperException.NodeExistsException e)
            {

View Full Code Here

                    public void run()
                    {
                        if (logger.isTraceEnabled())
                        logger.trace("Executing ZooKeeper client reset.");


                        ZooKeeper newZk = null;
                        try
                        {
                            boolean forceRebuild = false;
                            if (failedInstance.getState().isAlive())
                            {

View Full Code Here

    {
        if (logger.isTraceEnabled()) logger.trace("reestablished connection to " + connectString);


        if (isRunning)
        {
            final ZooKeeper last = zkref.getAndSet(newZk);
            if (last != null && last != newZk)
            {
                try {
                    last.close();
                } catch (final Throwable th) {}
            }
        }
        else
        {

View Full Code Here

0 1 2 3 4 5 6 7 8 9

TOP

Related Classes of org.apache.zookeeper.ZooKeeper

com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry

com.alibaba.otter.shared.arbitrate.impl.ArbitrateViewServiceImpl

com.alibaba.wasp.zookeeper.RecoverableZooKeeper

com.greplin.zookeeper.RobustZooKeeper

com.linkedin.helix.ZkTestHelper

com.linkedin.helix.ZkUnitTestBase

com.nokia.dempsy.cluster.zookeeper.TestFullApp

com.nokia.dempsy.cluster.zookeeper.TestZookeeperClusterResilience

com.nokia.dempsy.cluster.zookeeper.ZookeeperSession

com.pinterest.secor.common.ZookeeperConnector

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.