SignalR.Orleans

Orleans is a framework that provides a straight-forward approach to building distributed high-scale computing applications, without the need to learn and apply complex concurrency or other scaling patterns.

ASP.NET Core SignalR is a new library for ASP.NET Core developers that makes it incredibly simple to add real-time web functionality to your applications. What is "real-time web" functionality? It's the ability to have your server-side code push content to the connected clients as it happens, in real-time.

SignalR.Orleans is a package that allow us to enhance the real-time capabilities of SignalR by leveraging Orleans distributed cloud platform capabilities.

Installation

Installation is performed via NuGet

From Package Manager:

PS> Install-Package SignalR.Orleans

.Net CLI:

# dotnet add package SignalR.Orleans

Paket:

# paket add SignalR.Orleans

Configuration

Silo

We need to configure the Orleans Silo with the below:

• Use .UseSignalR() on ISiloHostBuilder.
• Make sure to call RegisterHub<THub>() where THub is the type of the Hub you want to be added to the backplane.

Example

var silo = new SiloHostBuilder()
  .UseSignalR()
  .RegisterHub<MyHub>() // You need to call this per `Hub` type.
  .AddMemoryGrainStorage("PubSubStore") // You can use any other storage provider as long as you have one registered as "PubSubStore".
  .Build();

await silo.StartAsync();

Configure Silo Storage Provider and Grain Persistance

Optional configuration to override the default implementation for both providers which by default are set as Memory.

Example

.UseSignalR(cfg =>
{
  cfg.ConfigureBuilder = (builder, config) =>
  {
    builder
      .AddMemoryGrainStorage(config.PubSubProvider)
      .AddMemoryGrainStorage(config.StorageProvider);
  };
})
.RegisterHub<MyHub>()

Client

Now your SignalR application needs to connect to the Orleans Cluster by using an Orleans Client:

• Use .UseSignalR() on IClientBuilder.

Example

var client = new ClientBuilder()
  .UseSignalR()
  .Build();

await client.Connect();

Somewhere in your Startup.cs:

• Add IClusterClient (created in the above example) to IServiceCollection.
• Use .AddSignalR() on IServiceCollection (this is part of Microsoft.AspNetCore.SignalR nuget package).
• Use AddOrleans() on .AddSignalR().

Example

public void ConfigureServices(IServiceCollection services)
{
  ...
  services
    .AddSingleton<IClusterClient>(client)
    .AddSignalR()
    .AddOrleans();
  ...
}

Great! Now you have SignalR configured and Orleans SignalR backplane built in Orleans!

Features

Hub Context

HubContext gives you the ability to communicate with the client from orleans grains (outside the hub).

Sample usage: Receiving server push notifications from message brokers, web hooks, etc. Ideally first update your grain state and then push signalr message to the client.

Example

public class UserNotificationGrain : Grain<UserNotificationState>, IUserNotificationGrain
{
  private HubContext<IUserNotificationHub> _hubContext;

  public override async Task OnActivateAsync()
  {
    _hubContext = GrainFactory.GetHub<IUserNotificationHub>();
    // some code...
    await _hubContext.User(this.GetPrimaryKeyString()).Send("Broadcast", State.UserNotification);
  }
}

Complete examples

Cohosting aspnetcore website and orleans

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.ResponseCompression;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Orleans;
using Orleans.Hosting;

// Cohosting aspnetcore website and Orleans with signalR
var host = Host.CreateDefaultBuilder(args)

  // Add the webhost with SignalR configured.
  .ConfigureWebHostDefaults(webBuilder =>
  {
    webBuilder.ConfigureServices((webBuilderContext, services) =>
    {
      // Add response compression used by the SignalR hubs.
      services.AddResponseCompression(opts =>
      {
        opts.MimeTypes = ResponseCompressionDefaults.MimeTypes.Concat(
            new[] { "application/octet-stream" });
      });

      // Adds SignalR hubs to the aspnetcore website 
      services.AddSignalR(options =>
      {
      })
      .AddOrleans(); // Tells SignalR to use Orleans as the backplane.
    });

    webBuilder.Configure((ctx, app) =>
    {
      // Adds response compression for use by the SignalR hubs
      app.UseResponseCompression();
      
      // Map SignalR hub endpoints
      app.UseEndpoints(endpoints =>
      {
        endpoints.MapHub<MyHubType1>("/hub1"); // use your own hub types
        endpoints.MapHub<MyHubType2>("/hub2"); // use your own hub types
        // ... etc
      });
    });
  })

  // Add Orleans with SignalR configured
  .UseOrleans((context, siloBuilder) =>
  {
    siloBuilder
      .UseSignalR(signalRConfig =>
      {
        // Optional.
        signalRConfig.UseFireAndForgetDelivery = true;

        signalRConfig.Configure((siloBuilder, signalRConstants) =>
        {
          // **************************************************************************
          // Use memory storage ONLY when your app is not clustered, otherwise you'll
          // need to use proper external storage providers
          // **************************************************************************

          siloBuilder.AddMemoryGrainStorage(signalRConstants.StorageProvider);
          // This wouldn't be be necessary if you already added "PubSubStore" elsewhere.
          siloBuilder.AddMemoryGrainStorage(signalRConstants.PubSubProvider /*Same as "PubSubStore"*/);
        });
      })

      // Allows Orleans grains to inject IHubContext<HubType>
      .RegisterHub<MyHubType1>()
      .RegisterHub<MyHubType2>();
      // ... etc
  })
  .UseConsoleLifetime()
  .Build();

await host.StartAsync();
await host.WaitForShutdownAsync(default);

Contributions

PRs and feedback are very welcome!