MediatR.Remote [한국어]

What is MediatR.Remote?

The MediatR.Remote library is an extension library of the IMediator implementation that distributes and relays remote objects. Inspired by distributed clustering frameworks like Akka.NET or Orleans, how to distribute via messages.

Modern software development starts small, but it becomes more complex and must scale at a rapid pace. However, although we always develop with scale expansion in mind, sometimes existing architectures become obstacles in designing new architectures. MediatR.Remote is a library designed to remote/distribute Mediator Pattern of IMediator.

MediatR.Remote means the role of each service based on Role. Each role may be located in one In-Process service, or it may be physically distributed, The focus is on shrinking or expanding the structure.

Install

dotnet add package MediatR.Remote

# ASP.NET Core
dotnet add package MediatR.Remote.Extensions.DependencyInjection

Getting Started

flowchart LR
    subgraph Public API
        A[IRemoteRequest Instance]
    end
    subgraph Internal API 1
        A -- HTTP Request --> B[IRemoteRequest Instance]
    end
    subgraph Internal API 2
        B -- HTTP Request --> C[IRemoteRequest Instance]
        C -- InProcess --> D[Handler]
    end
  

Loading

1. Message Definition

Implement the IRemoteRequest interface in your message class. or IRemoteNotification, which requires an implementation of the IRemoteStreamRequest interface.

public class HelloRemoteRequest : IRequest<HelloResponse>, IRemoteRequest
{
    public HelloRemoteRequest(string message)
    {
        Message = message;
    }

    public string Message { get; }

    public IEnumerable<string> SpanRoles => new[] { "internal-api1", "internal-api2" };
}

public class HelloResponse
{
    public HelloResponse(string message)
    {
        Message = message;
    }

    public string Message { get; }
}

2. Configuring Services

Define the role of the currently running service through the AddRemoteMediatR() method.

If you want to run all roles in one service in one In-Process, builder.Services.AddRemoteMediatR(new[] {"public-api", "internal-api1", "internal-api2"}, ...); You can define the role of the service like this:

builder.Services.AddMediatR(/* ..omitted.. */);
builder.Services.AddRemoteMediatR("public-api", remoteBuilder =>
{
    remoteBuilder.AddHttpStrategy("public-api", client => client.BaseAddress = new Uri("http://localhost:5000"));
    remoteBuilder.AddHttpStrategy("internal-api1", client => client.BaseAddress = new Uri("http://localhost:5010"));
    remoteBuilder.AddHttpStrategy("internal-api2", client => client.BaseAddress = new Uri("http://localhost:5020"));
});

3. Applying Middleware

// Map endpoint style of .NET 6 or higher.
app.UseRemoteMediatR(mediatorApplicationBuilder => mediatorApplicationBuilder.UseHttpListener());

// Middlewre style of .NET 5 or older.
app.UseRouting(); // <-- Routing middleware is required
app.UseRemoteMediatR(mediatorApplicationBuilder => mediatorApplicationBuilder.UseHttpListener());

4. Send Message

class Test
{
    private IRemoteMediator mediator; // or private IMediator mediator;

    public Test(IRemoteMediator mediator)
    {
        _mediator = mediator;
    }
    
    public async Task Call()
    {
        var request = new HelloRemoteRequest("HELLO WORLD");
        var response = await _mediator.Send(request);
    }
}

More Communication Strategies

HTTP

// Configure Service
services.AddRemoteMediatR("public-api", remoteBuilder =>
{
    remoteBuilder.AddHttpStrategy("internal-api1", client => client.BaseAddress = new Uri("http://localhost:5010"));
});

// Configure Middleware
app.UseRemoteMediatR(routeBuilder => routeBuilder.MapHttpListener().AllowAnonymous());

gRPC

Experimental feature

// Define Custom IMediator Interface
public interface IGrpcMediator : IRemoteMediator;

public class GrpcMediator(IMediator mediator) : RemoteMediator(mediator), IGrpcMediator
{
    public override string ProtocolName => "grpc";
}


// Configure Service
services.AddGrpc();
services.AddRemoteMediatR<IGrpcMediator, GrpcMediator>("public-api", "grpc", remoteBuilder =>
{
    remoteBuilder.AddGrpcStrategy("internal-api1", client => client.Address = new Uri("http://localhost:5011"));
});

// Configure Middleware
app.UseRemoteMediatR(applicationBuilder => applicationBuilder.UseGrpcListener());

More Examples

• Message Communication Example