我们是怎么实现Grpc CodeFirst

前言:

gRPC默认是ProtoFirst的，即先写 proto文件，再生成代码，需要人工维护proto，生成的代码也不友好，所以出现了gRPC CodeFirst，下面来说说我们是怎么实现gRPC CodeFirst

目录：

实现和WCF一样的CodeFirst

(1). 实现gRPC CodeFirst,  简化WCF一定要抽取接口的问题

(2). 通过代码生成proto和注释，给第三方语言使用

(3). 实现gRPC DashBoard，用于Http远程调用和管理

(4). 实现gRPC scope注入的三种方式(asp.net core3.0 grpc默认是scope)

(5). 实现服务注册与发现

(6). 实现分布式日志跟踪

(7). 日志监控等等

我们是怎么实现gRPC CodeFirst

1.要实现CodeFirst先要了解ProtoFirst生成的代码，下面我截了部分生成代码

(1).关键是这个BindService，用于把实现的gRPC方法绑定到ServerServiceDefinition

public static partial class Greeter
{
    static readonly string __ServiceName = "helloworld.Greeter";

    static readonly grpc::Marshaller<global::Helloworld.HelloRequest> __Marshaller_helloworld_HelloRequest = grpc::Marshallers.Create((arg) => global::Google.Protobuf.MessageExtensions.ToByteArray(arg), global::Helloworld.HelloRequest.Parser.ParseFrom);
    static readonly grpc::Marshaller<global::Helloworld.HelloReply> __Marshaller_helloworld_HelloReply = grpc::Marshallers.Create((arg) => global::Google.Protobuf.MessageExtensions.ToByteArray(arg), global::Helloworld.HelloReply.Parser.ParseFrom);

    static readonly grpc::Method<global::Helloworld.HelloRequest, global::Helloworld.HelloReply> __Method_SayHello = new grpc::Method<global::Helloworld.HelloRequest, global::Helloworld.HelloReply>(
        grpc::MethodType.Unary,
        __ServiceName,
        "SayHello",
        __Marshaller_helloworld_HelloRequest,
        __Marshaller_helloworld_HelloReply);

    static readonly grpc::Method<global::Helloworld.HelloRequest, global::Helloworld.HelloReply> __Method_SayHelloStream = new grpc::Method<global::Helloworld.HelloRequest, global::Helloworld.HelloReply>(
        grpc::MethodType.ClientStreaming,
        __ServiceName,
        "SayHelloStream",
        __Marshaller_helloworld_HelloRequest,
        __Marshaller_helloworld_HelloReply);

    /// <summary>Creates service definition that can be registered with a server</summary>
    /// <param name="serviceImpl">An object implementing the server-side handling logic.</param>
    public static grpc::ServerServiceDefinition BindService(GreeterBase serviceImpl)
    {
      return grpc::ServerServiceDefinition.CreateBuilder()
          .AddMethod(__Method_SayHello, serviceImpl.SayHello)
          .AddMethod(__Method_SayHelloStream, serviceImpl.SayHelloStream).Build();
    }

    /// <summary>Register service method with a service binder with or without implementation. Useful when customizing the  service binding logic.
    /// Note: this method is part of an experimental API that can change or be removed without any prior notice.</summary>
    /// <param name="serviceBinder">Service methods will be bound by calling <c>AddMethod</c> on this object.</param>
    /// <param name="serviceImpl">An object implementing the server-side handling logic.</param>
    public static void BindService(grpc::ServiceBinderBase serviceBinder, GreeterBase serviceImpl)
    {
      serviceBinder.AddMethod(__Method_SayHello, serviceImpl == null ? null : new grpc::UnaryServerMethod<global::Helloworld.HelloRequest, global::Helloworld.HelloReply>(serviceImpl.SayHello));
      serviceBinder.AddMethod(__Method_SayHelloStream, serviceImpl == null ? null : new grpc::ClientStreamingServerMethod<global::Helloworld.HelloRequest, global::Helloworld.HelloReply>(serviceImpl.SayHelloStream));
    }
}

(2).__Marshaller_helloworld_HelloRequest这个是实现protobuffer的序列化和反序列化的一个委托

服务的请求参数和返回参数，我们使用Protobuf-net来实现序列化和反序列化，和 WCF一样需要给类打上标签

    /// <summary>
    /// 加法请求参数
    /// </summary>
    [ProtoContract]
    public class AddRequest
    {
        /// <summary>
        /// 第一个数字
        /// </summary>
        [ProtoMember(1)]
        public int Num1 { get; set; }

        /// <summary>
        /// 第二个数字
        /// </summary>
        [ProtoMember(2)]
        public int Num2 { get; set; }
    }

2.要实现CodeFirst需要实现这个BindService，把我们的Grpc方法添加到ServerServiceDefinition

(1).我们让Grpc服务实现IGrpcService空接口，用于标识是GrpcService

    /// <summary>
    /// MathGrpc
    /// </summary>
    public class MathGrpc : IGrpcService
    {
        /// <summary>
        /// 加法
        /// </summary>
        /// <param name="request"></param>
        /// <param name="context"></param>
        /// <returns></returns>
        public Task<IntMessage> Add(AddRequest request, ServerCallContext context)
        {
            var result = new IntMessage();
            result.Value = request.Num1 + request.Num2;
            return Task.FromResult(result);
        }
   }

(2).获取实现了IGrpcService接口的类，然后反射获取方法，再添加到ServerServiceDefinition即可

这里调用了GrpcMethodHelper.AutoRegisterMethod()方法，这是通过反射自动注册GrpcMethod的方法

        /// <summary>
    /// 注入IGrpcService
    /// </summary>
    /// <param name="grpcServices"></param>
    /// <returns></returns>
    private ServerBuilder UseGrpcService(IEnumerable<IGrpcService> grpcServices)
    {
        var builder = ServerServiceDefinition.CreateBuilder();
        grpcServices.ToList().ForEach(grpc => GrpcMethodHelper.AutoRegisterMethod(grpc, builder));
        _serviceDefinitions.Add(builder.Build());
        return this;
    }

未完，待续，欢迎评论拍砖

这些功能早在2018年就已经实现并运行在生产，感兴趣的同学可以去 github上查看，你要的都有，欢迎提issue