java handwritten RPC from scratch (03) How to implement client-side calling server-side?

illustrate

java handwritten RPC from scratch (01) based on socket

java handwritten RPC from scratch (02)-netty4 to achieve client and server

After writing the client and server, how to implement the call between the client and the server?

Let's take a look at it together.

Interface definition

Calculation method

package com.github.houbb.rpc.common.service;

import com.github.houbb.rpc.common.model.CalculateRequest;
import com.github.houbb.rpc.common.model.CalculateResponse;

/**
 * <p> 计算服务接口 </p>
 *
 * <pre> Created: 2018/8/24 下午4:47  </pre>
 * <pre> Project: fake  </pre>
 *
 * @author houbinbin
 * @since 0.0.1
 */
public interface Calculator {

    /**
     * 计算加法
     * @param request 请求入参
     * @return 返回结果
     */
    CalculateResponse sum(final CalculateRequest request);

}

pojo

Corresponding parameter object:

• CalculateRequest

package com.github.houbb.rpc.common.model;

import java.io.Serializable;

/**
 * <p> 请求入参 </p>
 *
 * <pre> Created: 2018/8/24 下午5:05  </pre>
 * <pre> Project: fake  </pre>
 *
 * @author houbinbin
 * @since 0.0.3
 */
public class CalculateRequest implements Serializable {

    private static final long serialVersionUID = 6420751004355300996L;

    /**
     * 参数一
     */
    private int one;

    /**
     * 参数二
     */
    private int two;

    public CalculateRequest() {
    }

    public CalculateRequest(int one, int two) {
        this.one = one;
        this.two = two;
    }

    //getter setter toString

}

• CalculateResponse

package com.github.houbb.rpc.common.model;

import java.io.Serializable;

/**
 * <p> 请求入参 </p>
 *
 * <pre> Created: 2018/8/24 下午5:05  </pre>
 * <pre> Project: fake  </pre>
 *
 * @author houbinbin
 * @since 0.0.3
 */
public class CalculateResponse implements Serializable {

    private static final long serialVersionUID = -1972014736222511341L;

    /**
     * 是否成功
     */
   private boolean success;

    /**
     * 二者的和
     */
   private int sum;

    public CalculateResponse() {
    }

    public CalculateResponse(boolean success, int sum) {
        this.success = success;
        this.sum = sum;
    }

    //getter setter toString
}

Client

core part

RpcClient needs to add the corresponding Handler, adjust as follows:

Bootstrap bootstrap = new Bootstrap();
ChannelFuture channelFuture = bootstrap.group(workerGroup)
        .channel(NioSocketChannel.class)
        .option(ChannelOption.SO_KEEPALIVE, true)
        .handler(new ChannelInitializer<Channel>(){
            @Override
            protected void initChannel(Channel ch) throws Exception {
                ch.pipeline()
                        .addLast(new LoggingHandler(LogLevel.INFO))
                        .addLast(new CalculateRequestEncoder())
                        .addLast(new CalculateResponseDecoder())
                        .addLast(new RpcClientHandler());
            }
        })
        .connect(RpcConstant.ADDRESS, port)
        .syncUninterruptibly();

The handler swimlane in netty is designed very elegantly, allowing our code to be expanded flexibly.

Next we look at the corresponding implementation.

RpcClientHandler

package com.github.houbb.rpc.client.handler;

import com.github.houbb.log.integration.core.Log;
import com.github.houbb.log.integration.core.LogFactory;
import com.github.houbb.rpc.client.core.RpcClient;
import com.github.houbb.rpc.common.model.CalculateRequest;
import com.github.houbb.rpc.common.model.CalculateResponse;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

/**
 * <p> 客户端处理类 </p>
 *
 * <pre> Created: 2019/10/16 11:30 下午  </pre>
 * <pre> Project: rpc  </pre>
 *
 * @author houbinbin
 * @since 0.0.2
 */
public class RpcClientHandler extends SimpleChannelInboundHandler {

    private static final Log log = LogFactory.getLog(RpcClient.class);

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        CalculateRequest request = new CalculateRequest(1, 2);

        ctx.writeAndFlush(request);
        log.info("[Client] request is :{}", request);
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        CalculateResponse response = (CalculateResponse)msg;
        log.info("[Client] response is :{}", response);
    }

}

This is relatively simple. In channelActive, we directly initiate the call. For simplicity, the input parameter is fixed here.

Monitor the corresponding results of the server in channelRead0 and log output.

CalculateRequestEncoder

The request parameter is an object, netty cannot be directly transmitted, we convert it to a basic object:

package com.github.houbb.rpc.client.encoder;

import com.github.houbb.rpc.common.model.CalculateRequest;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

/**
 * @author binbin.hou
 * @since 0.0.3
 */
public class CalculateRequestEncoder extends MessageToByteEncoder<CalculateRequest> {

    @Override
    protected void encode(ChannelHandlerContext ctx, CalculateRequest msg, ByteBuf out) throws Exception {
        int one = msg.getOne();
        int two = msg.getTwo();

        out.writeInt(one);
        out.writeInt(two);
    }

}

CalculateResponseDecoder

The same applies to the response from the server.

We need to convert the basic types and packages into the objects we need.

package com.github.houbb.rpc.client.decoder;

import com.github.houbb.rpc.common.model.CalculateResponse;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

/**
 * 响应参数解码
 * @author binbin.hou
 * @since 0.0.3
 */
public class CalculateResponseDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        boolean success = in.readBoolean();
        int sum = in.readInt();

        CalculateResponse response = new CalculateResponse(success, sum);
        out.add(response);
    }

}

Server

Set processing class

The processing classes in RpcServer need to be adjusted slightly, and the others remain unchanged.

ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(workerGroup, bossGroup)
        .channel(NioServerSocketChannel.class)
        // 打印日志
        .handler(new LoggingHandler(LogLevel.INFO))
        .childHandler(new ChannelInitializer<Channel>() {
            @Override
            protected void initChannel(Channel ch) throws Exception {
                ch.pipeline()
                        .addLast(new CalculateRequestDecoder())
                        .addLast(new CalculateResponseEncoder())
                        .addLast(new RpcServerHandler());
            }
        })
        // 这个参数影响的是还没有被accept 取出的连接
        .option(ChannelOption.SO_BACKLOG, 128)
        // 这个参数只是过一段时间内客户端没有响应，服务端会发送一个 ack 包，以判断客户端是否还活着。
        .childOption(ChannelOption.SO_KEEPALIVE, true);

RpcServerHandler

At the beginning, this is an empty implementation, let's add the corresponding implementation.

package com.github.houbb.rpc.server.handler;

import com.github.houbb.log.integration.core.Log;
import com.github.houbb.log.integration.core.LogFactory;
import com.github.houbb.rpc.common.model.CalculateRequest;
import com.github.houbb.rpc.common.model.CalculateResponse;
import com.github.houbb.rpc.common.service.Calculator;
import com.github.houbb.rpc.server.service.CalculatorService;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

/**
 * @author binbin.hou
 * @since 0.0.1
 */
public class RpcServerHandler extends SimpleChannelInboundHandler {

    private static final Log log = LogFactory.getLog(RpcServerHandler.class);

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final String id = ctx.channel().id().asLongText();
        log.info("[Server] channel {} connected " + id);
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        final String id = ctx.channel().id().asLongText();

        CalculateRequest request = (CalculateRequest)msg;
        log.info("[Server] receive channel {} request: {} from ", id, request);

        Calculator calculator = new CalculatorService();
        CalculateResponse response = calculator.sum(request);

        // 回写到 client 端
        ctx.writeAndFlush(response);
        log.info("[Server] channel {} response {}", id, response);
    }

}

After reading the client's access, we obtain the calculated input parameter CalculateRequest, then call the sum method to obtain the corresponding CalculateResponse, and notify the client of the result.

CalculateRequestDecoder

Here is a one-to-one correspondence with the client, we first convert the basic type passed by netty into a CalculateRequest object.

package com.github.houbb.rpc.server.decoder;

import com.github.houbb.rpc.common.model.CalculateRequest;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

/**
 * 请求参数解码
 * @author binbin.hou
 * @since 0.0.3
 */
public class CalculateRequestDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        int one = in.readInt();
        int two = in.readInt();

        CalculateRequest request = new CalculateRequest(one, two);
        out.add(request);
    }

}

CalculateResponseEncoder

Similar to the client here, we need to convert the response to a basic type for network transmission.

package com.github.houbb.rpc.server.encoder;

import com.github.houbb.rpc.common.model.CalculateResponse;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

/**
 * @author binbin.hou
 * @since 0.0.3
 */
public class CalculateResponseEncoder extends MessageToByteEncoder<CalculateResponse> {

    @Override
    protected void encode(ChannelHandlerContext ctx, CalculateResponse msg, ByteBuf out) throws Exception {
        boolean success = msg.isSuccess();
        int result = msg.getSum();
        out.writeBoolean(success);
        out.writeInt(result);
    }

}

CalculatorService

The implementation class corresponding to the server.

public class CalculatorService implements Calculator {

    @Override
    public CalculateResponse sum(CalculateRequest request) {
        int sum = request.getOne()+request.getTwo();

        return new CalculateResponse(true, sum);
    }

}

test

Server

Start the server:

new RpcServer().start();

Server startup log:

[DEBUG] [2021-10-05 11:53:11.795] [main] [c.g.h.l.i.c.LogFactory.setImplementation] - Logging initialized using 'class com.github.houbb.log.integration.adaptors.stdout.StdOutExImpl' adapter.
[INFO] [2021-10-05 11:53:11.807] [Thread-0] [c.g.h.r.s.c.RpcServer.run] - RPC 服务开始启动服务端
十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler channelRegistered
信息: [id: 0xd399474f] REGISTERED
十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler bind
信息: [id: 0xd399474f] BIND: 0.0.0.0/0.0.0.0:9527
十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler channelActive
信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] ACTIVE
[INFO] [2021-10-05 11:53:13.101] [Thread-0] [c.g.h.r.s.c.RpcServer.run] - RPC 服务端启动完成，监听【9527】端口

Client

Start the client:

new RpcClient().start();

The log is as follows:

[DEBUG] [2021-10-05 11:54:12.158] [main] [c.g.h.l.i.c.LogFactory.setImplementation] - Logging initialized using 'class com.github.houbb.log.integration.adaptors.stdout.StdOutExImpl' adapter.
[INFO] [2021-10-05 11:54:12.164] [Thread-0] [c.g.h.r.c.c.RpcClient.run] - RPC 服务开始启动客户端
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRegistered
信息: [id: 0x4d75c580] REGISTERED
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler connect
信息: [id: 0x4d75c580] CONNECT: /127.0.0.1:9527
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelActive
信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] ACTIVE
[INFO] [2021-10-05 11:54:13.403] [Thread-0] [c.g.h.r.c.c.RpcClient.run] - RPC 服务启动客户端完成，监听端口：9527
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler write
信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] WRITE: 8B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 00 00 00 01 00 00 00 02                         |........        |
+--------+-------------------------------------------------+----------------+
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler flush
信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] FLUSH
[INFO] [2021-10-05 11:54:13.450] [nioEventLoopGroup-2-1] [c.g.h.r.c.c.RpcClient.channelActive] - [Client] request is :CalculateRequest{one=1, two=2}
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRead
信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] READ: 5B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 00 00 00 03                                  |.....           |
+--------+-------------------------------------------------+----------------+
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelReadComplete
信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] READ COMPLETE
[INFO] [2021-10-05 11:54:13.508] [nioEventLoopGroup-2-1] [c.g.h.r.c.c.RpcClient.channelRead0] - [Client] response is :CalculateResponse{success=true, sum=3}

As you can see, the corresponding request parameters and response results are output.

Of course, the server also has corresponding new logs at this time:

十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRead
信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] READ: [id: 0xbc9f5927, L:/127.0.0.1:9527 - R:/127.0.0.1:54030]
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelReadComplete
信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] READ COMPLETE
[INFO] [2021-10-05 11:54:13.432] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelActive] - [Server] channel {} connected 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927
[INFO] [2021-10-05 11:54:13.495] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927 request: CalculateRequest{one=1, two=2} from 
[INFO] [2021-10-05 11:54:13.505] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927 response CalculateResponse{success=true, sum=3}

summary

In order to facilitate everyone to learn, the above source code has been open source:

https://github.com/houbb/rpc

I hope this article is helpful to you. If you like it, please like, collect and forward a wave.

I am an old horse, and I look forward to meeting you next time.