Netty核心技术十一--用Netty 自己 实现 dubbo RPC

**Netty核心技术十一--用Netty自己实现Dubbo RPC**

在前面的文章中，我们已经学习了Netty的基本使用、TCP编程模型、UDP编程模型等内容。今天我们要讲的是一个更高级的主题：如何使用Netty来实现Dubbo RPC。

**什么是Dubbo RPC？**

Dubbo RPC是一种分布式服务框架，支持多语言开发，包括Java、Python、PHP等。它提供了服务发现、负载均衡、容错等功能，使得我们可以轻松地在分布式环境中部署和管理服务。

**为什么要用Netty来实现Dubbo RPC？**

虽然Dubbo RPC本身已经支持多种协议，如Hessian、JSON-RPC、Thrift等，但如果我们想使用Netty作为底层通信框架，那么就需要自己实现一个新的RPC协议。这个新协议将基于Netty的编程模型，提供更高效和灵活的服务调用。

**Netty RPC协议设计**

我们的Netty RPC协议将支持以下功能：

* **服务注册**:客户端可以向服务端注册自己的服务。
* **服务发现**:服务端可以根据服务名称找到相应的服务实例。
* **请求响应**:客户端可以向服务端发送请求，服务端返回相应的结果。

**Netty RPC协议实现**

下面是我们基于Netty来实现Dubbo RPC协议的核心代码：

###1. Netty RPC Server

javaimport io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;

public class NettyRpcServer {

 private int port;

 public NettyRpcServer(int port) {
 this.port = port;
 }

 public void start() throws Exception {
 EventLoopGroup group = new NioEventLoopGroup();
 try {
 ServerBootstrap bootstrap = new ServerBootstrap();
 bootstrap.group(group)
 .channel(io.netty.channel.nio.NioSocketChannel.class)
 .childHandler(new ChannelInitializer() {

 @Override protected void initChannel(SocketChannel ch) throws Exception {
 //服务注册和发现逻辑 NettyRpcServerHandler handler = new NettyRpcServerHandler();
 ch.pipeline().addLast(handler);
 }
 })
 .option(ChannelOption.SO_BACKLOG,128)
 .childOption(ChannelOption.SO_KEEPALIVE, true);

 ChannelFuture future = bootstrap.bind(port).sync();

 System.out.println("Netty RPC Server started on port " + port);

 //服务注册和发现逻辑 NettyRpcServerHandler handler = new NettyRpcServerHandler();
 future.channel().pipeline().addLast(handler);

 future.channel().closeFuture().addListener((future1) -> {
 System.out.println("Netty RPC Server stopped");
 });

 } catch (Exception e) {
 System.err.println("Netty RPC Server failed to start");
 throw new Exception(e);
 }
 }

}

javaimport io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;

public class NettyRpcClient {

 private String host;
 private int port;

 public NettyRpcClient(String host, int port) {
 this.host = host;
 this.port = port;
 }

 public void start() throws Exception {
 EventLoopGroup group = new NioEventLoopGroup();
 try {
 Bootstrap bootstrap = new Bootstrap();
 bootstrap.group(group)
 .channel(io.netty.channel.nio.NioSocketChannel.class)
 .handler(new ChannelInitializer() {

 @Override protected void initChannel(SocketChannel ch) throws Exception {
 //请求响应逻辑 NettyRpcClientHandler handler = new NettyRpcClientHandler();
 ch.pipeline().addLast(handler);
 }
 })
 .option(ChannelOption.SO_BACKLOG,128)
 .childOption(ChannelOption.SO_KEEPALIVE, true);

 ChannelFuture future = bootstrap.connect(host, port).sync();

 System.out.println("Netty RPC Client connected to server on host " + host + ", port " + port);

 //请求响应逻辑 NettyRpcClientHandler handler = new NettyRpcClientHandler();
 future.channel().pipeline().addLast(handler);

 future.channel().closeFuture().addListener((future1) -> {
 System.out.println("Netty RPC Client disconnected from server");
 });

 } catch (Exception e) {
 System.err.println("Netty RPC Client failed to connect to server");
 throw new Exception(e);
 }
 }

}

javaimport io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class NettyRpcServerHandler extends SimpleChannelInboundHandler {

 @Override protected void channelRead0(ChannelHandlerContext ctx, NettyRpcRequest msg) throws Exception {
 //服务注册和发现逻辑 String serviceName = msg.getServiceName();
 String serviceInstance = getServiceInstance(serviceName);
 if (serviceInstance != null) {
 NettyRpcResponse response = new NettyRpcResponse();
 response.setServiceName(serviceName);
 response.setServiceInstance(serviceInstance);
 ctx.writeAndFlush(response);
 } else {
 NettyRpcResponse response = new NettyRpcResponse();
 response.setServiceName(serviceName);
 response.setError("Service not found");
 ctx.writeAndFlush(response);
 }
 }

}

javaimport io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class NettyRpcClientHandler extends SimpleChannelInboundHandler {

 @Override protected void channelRead0(ChannelHandlerContext ctx, NettyRpcResponse msg) throws Exception {
 //请求响应逻辑 String serviceName = msg.getServiceName();
 String serviceInstance = getServiceInstance(serviceName);
 if (serviceInstance != null) {
 System.out.println("Received response from server for service " + serviceName + ": " + serviceInstance);
 } else {
 System.out.println("Received error response from server for service " + serviceName + ": " + msg.getError());
 }
 }

}

javapublic String getServiceInstance(String serviceName) {
 //服务注册和发现逻辑 Map services = new HashMap<>();
 services.put("service1", "instance1");
 services.put("service2", "instance2");
 return services.get(serviceName);
}