解析MapReduce原理–筆記(9)hadoopRPC基礎

public static VersionedProtocol getProxy/waitForProxy():構造一個客戶端代理對象，用于向服務器發送RPC請求。public static Server getServer():為某個協議示例構造一個服務器對象，用于處理客戶端發送的請求。

1.定義RPC協議。RPC協議是客戶端與服務器端之間的通信接口，它定義了服務器端對外提供的服務接口。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.實現RPC協議。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.構造并啟動RPC Serverserver = RPC.getServer(new ClientProtocolImpl(),serverHost,serverPort,numHandlers,false,conf);//numHandlers表示服務器端處理請求的線程數目。server.start();4.構造RPC Client，并發送RPC請求。proxy = (ClientProtocol)RPC.getProxy(ClientProtocol.class,ClientProtocol.versionID,addr,conf);int result = proxy.add(4,5);String echoResult = proxy.echo("hello");