RPC之gRPC的使用(Java+Nodejs)

本文介绍在Java中使用gRPC的过程。一般来说，主要包含以下的三个步骤
1）在.proto文件中定义提供的服务
2）使用protocol buffer编译器编译文件
3）使用gRPC API来创建服务端和客户端，并进行调用。

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下载和安装需要的软件

1）Protocol Buffers
结构化数据序列化机制
https://github.com/protocolbuffers/protobuf/releases
使用示例：

protoc --java_out=./ *.proto

2）protoc-gen-grpc-java
用于生成RPC通信代码
http://jcenter.bintray.com/io/grpc/protoc-gen-grpc-java/
使用示例【使用Protobuf-Plugin机制】：

protoc --plugin=protoc-gen-grpc-java=protoc-gen-grpc-java-1.19.0-windows-x86_64.exe --grpc-java_out=./ *.proto

使用Maven构建gRPC

1）修改pmo.xml

    
        UTF-8
        3.7.0
        1.19.0
    

          
        
          io.grpc
          grpc-netty-shaded
          ${grpc.version}
        
        
          io.grpc
          grpc-protobuf
          ${grpc.version}
        
        
          io.grpc
          grpc-stub
          ${grpc.version}
        
        
        
          com.google.protobuf
          protobuf-java
          ${protobuf.version}
        
        
        
          com.google.protobuf
          protobuf-java-util
          ${protobuf.version}
        
    
    
        
            
                
                kr.motd.maven
                os-maven-plugin
                1.6.1
            
        
        
            
                org.xolstice.maven.plugins
                protobuf-maven-plugin
                0.6.1
                
                    
                    
                    
                    
                    
                    
                    
                    
                    
                    false
                    com.google.protobuf:protoc:${protobuf.version}:exe:${os.detected.classifier}
                    grpc-java
                    io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}
                
                
                    
                        
                            compile
                            compile-custom
                        
                    
                
            
        
    

默认情况下，该插件会查找 src/main/proto路径下的proto文件。该在路径下的任何子文件夹都会作为proto文件中使用的包路径。

2）在src/main/proto下创建proto文件(HarLog.proto)

syntax = "proto3";

option java_multiple_files = true;
option java_package = "com.ultrapower.ioss.proto";
option java_outer_classname = "HarLogProto";

package com.ultrapower.grpc.har;

message HarLogResovleRequest{
    string url = 1 ;
    string file_name = 2;
    string file_dir = 3;
    string context = 4;
}

message HarLogResovleResponse{
    int32 code = 1 ;
}

service HarLogService{
    rpc ResovleHarLog(HarLogResovleRequest) returns (HarLogResovleResponse);
    rpc BatchResovleHarLog(HarLogResovleRequest) returns (HarLogResovleResponse);

}

3）编译文件

mvn protobuf:compile 
或
mvn compile

在target\generated-sources\protobuf下会生成以下两个文件夹

其中java文件夹下面包含了我们定义的message，而grpc-java下存放的是服务端和客户端都要使用的service。
基于上面的proto文件，生成了两个java文件

1，HarLogServiceGrpc.java   位于grpc-java下
2，HarLogProto.java等其他文件位于java下

4）服务端服务实现类代码

package com.ultrapower.ioss.proto;

public class HarLogServiceImpl extends HarLogServiceGrpc.HarLogServiceImplBase {

    @Override
    public void resovleHarLog(com.ultrapower.ioss.proto.HarLogResovleRequest request,
            io.grpc.stub.StreamObserver responseObserver) {
        System.out.println(request.getUrl());
        System.out.println(request.getFileName());
        System.out.println(request.getFileDir());
        System.out.println(request.getContext());

        responseObserver.onNext(HarLogResovleResponse.newBuilder().setCode(200).build());
        responseObserver.onCompleted();
    }

    @Override
    public void batchResovleHarLog(com.ultrapower.ioss.proto.HarLogResovleRequest request,
            io.grpc.stub.StreamObserver responseObserver) {
        responseObserver.onNext(HarLogResovleResponse.newBuilder().setCode(200).build());
        responseObserver.onCompleted();
    }
}

5）服务端启动类

package com.ultrapower.ioss.proto;

import java.io.IOException;

import io.grpc.Server;
import io.grpc.ServerBuilder;

public class RpcServerApp {

    private Server server;
    private int port = 50051;

    public void start() throws IOException {
        server = ServerBuilder.forPort(port)
                .addService(new HarLogServiceImpl())
                .build()
                .start();

        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                RpcServerApp.this.stop();
            }
        });
    }

    private void stop() {
        if (server != null) {
            server.shutdown();
        }
    }

    private void blockUntilShutdown() throws InterruptedException {
        if (server != null) {
            server.awaitTermination();
        }
    }

    public static void main(String[] args) throws Exception {
        final RpcServerApp server = new RpcServerApp();
        server.start();
        server.blockUntilShutdown();
    }

}

Nodejs端客户端

1）添加依赖

cnpm install --save grpc-tools
cnpm install --save google-protobuf 
cnpm install --save grpc
cnpm install --save @grpc/proto-loader
cnpm install --save @grpc/grpc-js

2）客户端代码

var grpc = require('grpc');
var PROTO_PATH = __dirname + '/../grpc/protos/HarLog.proto';
var protoLoader = require('@grpc/proto-loader');
var packageDefinition = protoLoader.loadSync(
    PROTO_PATH,
    {keepCase: true,
     longs: String,
     enums: String,
     defaults: true,
     oneofs: true
    });
var protoDescriptor = grpc.loadPackageDefinition(packageDefinition);
//protoDescriptor + "文件中定义的package"
var harlog = protoDescriptor.com.ultrapower.grpc.har;

/*
    创建RPC客户端
*/
function getGrpcClient(){
    //创建客户端
    let client = new harlog.HarLogService('localhost:50051',grpc.credentials.createInsecure());
    return client ; 
}

/*
    请求JAVA端解析生成的某个HAR文件
*/
function resovleHarLog(request){
    let client = getGrpcClient() ;
    //请求数据
    /*
    let request = {
            url:'',
            file_name:'',
            file_dir:'',
            context:''
    } ;
    */
    client.resovleHarLog(request,function(error,response){
        //console.log('Greeting:', response.code);
        console.log('Greeting:', JSON.stringify(response));
    })
}
/*
    请求JAVA端解析指定目录下所有的HAR文件
    @param dirPath 存放HAR文件的目录路径
*/
function batchResovleHarlog(request){
    let client = getGrpcClient() ;
    client.batchResovleHarLog(request,function(error,response){
        console.log('Greeting:', response.message);
    })
}

//测试
resovleHarLog({
            url:'www.baidu.com',
            file_name:'bai.jar',
            file_dir:'c://d',
            context:'dsfdfdsd'
    } ) ;

exports.resovleHarLog = resovleHarLog;
exports.batchResovleHarlog = batchResovleHarlog;

基于Java的客户端

package com.ultrapower.ioss.proto;

import java.util.concurrent.TimeUnit;

import io.grpc.ManagedChannel;
import io.grpc.netty.shaded.io.grpc.netty.NegotiationType;
import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;

public class Client {

    private final ManagedChannel channel;

    private final HarLogServiceGrpc.HarLogServiceBlockingStub blockingStub;

    /**
     * 创建服务端连接，并创建“桩”
     */
    public Client(String host, int port) {
        channel = NettyChannelBuilder.forAddress(host, port).negotiationType(NegotiationType.PLAINTEXT).build();
        blockingStub = HarLogServiceGrpc.newBlockingStub(channel);
    }

    public void shutdown() throws InterruptedException {
        channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
    }

    /**
     * 向服务端发送请求
     */
    public void resovleHarLog() {
        try {
            HarLogResovleRequest request = HarLogResovleRequest.newBuilder().setUrl("www.baidu.com").setFileName("test")
                    .build();
            HarLogResovleResponse response = blockingStub.resovleHarLog(request);
            System.out.println("result from server: " + response.getCode());
        } catch (RuntimeException e) {
            System.out.println("RPC failed:" + e.getMessage());
            return;
        }
    }

    public static void main(String[] args) throws Exception {
        Client client = new Client("127.0.0.1", 50051);
        try {
            client.resovleHarLog();
        } finally {
            client.shutdown();
        }
    }
}

基于Nodejs的服务端

var grpc = require('grpc');
var PROTO_PATH = __dirname + '/../grpc/protos/HarLog.proto';
var protoLoader = require('@grpc/proto-loader');
var packageDefinition = protoLoader.loadSync(
    PROTO_PATH,
    {keepCase: true,
     longs: String,
     enums: String,
     defaults: true,
     oneofs: true
    });
var protoDescriptor = grpc.loadPackageDefinition(packageDefinition);
//protoDescriptor + "文件中定义的package"
var harlog = protoDescriptor.com.ultrapower.grpc.har;

/*
    远程调用的resovleHarLog方法.
    @param call 请求， 通过call.request可以得到请求参数
    @param callback，调用完成后返回给调用端的结果
*/
function resovleHarLog(call, callback) {
    let req = call.request ;
    console.log(JSON.stringify(req)) ;
  //callback(null, {message: 'Hello ' + call.request.name});
  callback(null, {code: 300});
}

function batchResovleHarLog(call, callback) {
    let req = call.request ;
    console.log(JSON.stringify(req)) ;
  //callback(null, {message: 'Hello again, ' + call.request.name});
  callback(null, {code: 300});
}

/*
    创建并启动服务端
*/
function startup() {
  var server = new grpc.Server();
  server.addProtoService(harlog.HarLogService.service,
                         {resovleHarLog: resovleHarLog, batchResovleHarLog: batchResovleHarLog});
  server.bind('0.0.0.0:50052', grpc.ServerCredentials.createInsecure());
  server.start();
}

//启动服务
startup() ;

exports.startup = startup;