storm DRPC问题

一、配置集群storm.yaml文件，配置drpc.server。

二、开启drpc服务，storm drpc。

三、编写DrpcTopology程序。如下：

<span style="font-size:24px;">import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.LocalDRPC;
import org.apache.storm.StormSubmitter;
import org.apache.storm.drpc.LinearDRPCTopologyBuilder;
import org.apache.storm.topology.BasicOutputCollector;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.base.BaseBasicBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;

/**
 * This topology is a basic example of doing distributed RPC on top of Storm. It implements a function that appends a
 * "!" to any string you send the DRPC function.
 *
 * @see <a href="http://storm.apache.org/documentation/Distributed-RPC.html">Distributed RPC</a>
 */
public class Drpc {
  public static class ExclaimBolt extends BaseBasicBolt {
    @Override
    public void execute(Tuple tuple, BasicOutputCollector collector) {
      String input = tuple.getString(1);
      collector.emit(new Values(tuple.getValue(0), input + "!"));
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
      declarer.declare(new Fields("id", "result"));
    }

  }

  public static void main(String[] args) throws Exception {
    LinearDRPCTopologyBuilder builder = new LinearDRPCTopologyBuilder("exclamation");
    builder.addBolt(new ExclaimBolt(), 3);

    Config conf = new Config();

    if (args == null || args.length == 0) {
      LocalDRPC drpc = new LocalDRPC();
      LocalCluster cluster = new LocalCluster();

      cluster.submitTopology("drpc-demo", conf, builder.createLocalTopology(drpc));

      for (String word : new String[]{ "hello", "goodbye" }) {
        System.out.println("Result for \"" + word + "\": " + drpc.execute("exclamation", word));
      }
     
    }
    else {
      conf.setNumWorkers(3);
      StormSubmitter.submitTopologyWithProgressBar(args[0], conf, builder.createRemoteTopology());
    }
  }
}
</span>

四、提交jar文件至集群后，用storm1.0.1api编写drpcClient程序总是报错，程序如下：

<span style="font-size:24px;">import org.apache.storm.Config;
import org.apache.storm.utils.DRPCClient;
public class DrpcClient {

	public static void main(String[] args) throws Exception {

		Config conf=new Config();
		conf.setDebug(false);
		DRPCClient client=new DRPCClient(conf, "storm2", 3772);
		System.out.println(client.execute("exclamation", "hello"));
	}

}</span>

错误如下：
Exception in thread "main" java.lang.RuntimeException: java.lang.NullPointerException
at org.apache.storm.security.auth.AuthUtils.GetTransportPlugin(AuthUtils.java:267)
at org.apache.storm.security.auth.ThriftClient.reconnect(ThriftClient.java:88)
at org.apache.storm.security.auth.ThriftClient.<init>(ThriftClient.java:69)
at org.apache.storm.utils.DRPCClient.<init>(DRPCClient.java:44)
at org.apache.storm.utils.DRPCClient.<init>(DRPCClient.java:39)
at drpc.DrpcClient.main(DrpcClient.java:16)
Caused by: java.lang.NullPointerException
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:190)
at org.apache.storm.security.auth.AuthUtils.GetTransportPlugin(AuthUtils.java:263)
... 5 more

改用storm 0.9.6api则没有问题，可以正常调用server。

<span style="font-size:24px;">import backtype.storm.utils.DRPCClient;
public class DrpcClient {

	public static void main(String[] args) throws Exception {

		DRPCClient client=new DRPCClient("storm2", 3772);
		System.out.println(client.execute("exclamation", "年后"));
	}

}
</span>