解析MapReduce原理–笔记(9)hadoopRPC基础

public static VersionedProtocol getProxy/waitForProxy():构造一个客户端代理对象，用于向服务器发送RPC请求。public static Server getServer():为某个协议示例构造一个服务器对象，用于处理客户端发送的请求。

1.定义RPC协议。RPC协议是客户端与服务器端之间的通信接口，它定义了服务器端对外提供的服务接口。interface ClientProtocol extends org.apache.hadoop.ipc.VersionedProtocol{public static final long versionID=1L;String echo(String value) throws IOException;int add(int v1,int v2) throws IOException;}2.实现RPC协议。public static class ClientProtocolImpl implements ClientProtocl{public long getProtocolVersion(String protocol,long clientVersion){return ClientProtocol.versionID ;}public String echo(String value) throws IOException{return value;}public int add(int v1,int v2) throws IOException{return v1+v2;}}3.构造并启动RPC Serverserver = RPC.getServer(new ClientProtocolImpl(),serverHost,serverPort,numHandlers,false,conf);//numHandlers表示服务器端处理请求的线程数目。server.start();4.构造RPC Client，并发送RPC请求。proxy = (ClientProtocol)RPC.getProxy(ClientProtocol.class,ClientProtocol.versionID,addr,conf);int result = proxy.add(4,5);String echoResult = proxy.echo("hello");