hadoop RPC(三)

RPC

远程过程调用(RPC):hadoop的节点之间的进程通信(类与类之间),以及与客户端的通信.心跳也是通过RPC完成的
为什么datanode定期会向Namenode汇报block信息

RPC的现实技术:动态代理,反射,socker通信生成RPC客户端

serveice

package cn.itcast.hadoop.hdfs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RPC.Builder;
import org.apache.hadoop.ipc.RPC.Server;

publci class ServiceStart{

    public static void main(String[] args) 
        throws HadoopIllegalArgumentException, IOException {

        Builder builder = new RPC.Builder(new Configuration());
        builder.setBindAddress("cluster1").setPort(10000)
            .setProtocol(LoginInter.class).setInstance(new LoginServer());
        Server server = builder.build();
        server.start();
        // 多个业务逻辑处理
    }

}

package cn.itcast.hadoop.hdfs;

public class LoginServer implements LoginInter {
    @Override
    public String login(String username, String passwd) {
        return username + "success!!";
    }
}

client

package cn.itcast.hadoop.hdfs;

import java.io.IOException;
import java.net.InetSocketAddress;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;

public class LoginControl {

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        LoginInter proxy = RPC.getProxy(LoginInter.class, 1L,
         new InetSocketAddress("192.168.1.222",10000), new Configuration());
        String r = proxy.login("femn", "femn");
        System.out.println(r);
        // 当增加服务器提供服务时,客户端能够感知服务端.
        // 在不改变的情况下,知道去调用新服务器的服务
        // 服务调用动态转发和负载均衡的实现,使用zookeeper可以很容易的实现
    }
}

service and client

package cn.itcast.hadoop.hdfs;

public interface LoginInter {
    public static final long versionId=1L;
    public String login(String username,String passwd);
}