Awesome Open Source
Awesome Open Source

WebStreams

Serve APIs returning & consuming observable streams over WebSockets using .NET

Think of it as ASP.NET Web API but with controllers which return IObservable<T> instead of Task<T>, which allows you to easily push to clients. Controllers can also consume IObservable<T> parameters, see the ChatController example.

Why not SignalR?

SignalR is great for a lot of realtime applications which scaleout easily, but it's not easy to create realtime apps which require authoritative logic - take a game for example, or other complex apps. This is perhaps because SignalR gives you transparent scale-out, so the rendezvous point for notifications (Service Bus, SQL Server, etc) does not contain application logic.

Instead, WebStreams does not give you transparent scale-out at all. Scale-out can easily be achieved using Service Bus or another backplane like in a SignalR app, but often scale-out will sit in Microsoft Orleans or another Actor framework. Another option for scale-out is Azure Event Hubs, which can contain application logic.

See the WebStreamSamples repository for a sample server with a Web client.

TODO: publish sample which scales out app logic using Microsoft Orleans.

Installation

PM> Install-Package WebStreams.Server

NuGet will pull in all dependencies (Owin, Json.NET, Rx).

Usage

Call UseWebStream() in your OWIN startup method. See below for an example.

StockController.cs

[RoutePrefix("/stock")]
public class StockTickerController
{
  private readonly ConcurrentDictionary<string, IObservable<Stock>> stocks =
    new ConcurrentDictionary<string, IObservable<Stock>>();

  [Route("ticker")]
  public IObservable<Stock> GetTicker(string symbol)
  {
    return this.GetStockTicker(symbol);
  }
  private static IObservable<Stock> CreateStockTicker(string symbol)
  {
    var random = new Random();
    // Construct a shoddy, pseudo-random walk.
    return
      Observable.Interval(TimeSpan.FromSeconds(0.1))
        .Select(time => random.NextDouble())
        .Scan((double)random.Next(1000), (prev, randomVal) =>
          Math.Max(0, prev * (1 + (0.01 * (randomVal - 0.5)))))
        .Select(val => new Stock(symbol, val, DateTime.UtcNow));
  }
  private IObservable<Stock> GetStockTicker(string symbol)
  {
    return this.stocks.GetOrAdd(symbol, CreateStockTicker);
  }
}

In your OWIN Startup.cs

public void Configuration(IAppBuilder app)
{
    app.UseWebStream();
}
Alternatives To Webstreams.server
Select To Compare


Alternative Project Comparisons
Related Awesome Lists
Top Programming Languages
Top Projects

Get A Weekly Email With Trending Projects For These Topics
No Spam. Unsubscribe easily at any time.
C Sharp (166,272
Stream (21,094
Websocket (13,910
Observables (3,555
Signalr (1,045
Owin (460
Orleans (314