102 lines
3.3 KiB
C#
102 lines
3.3 KiB
C#
using Microsoft.Owin;
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using Owin;
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Threading.Tasks;
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using System.Web.Http;
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namespace WebServer.OWIN
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{
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public class StartupSSE
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{
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public void Configuration(IAppBuilder app)
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{
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var api = new Api();
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app.Run(context => api.Invoke(context));
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}
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public class Subscriber
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{
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private StreamWriter _writer;
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private TaskCompletionSource<bool> _tcs;
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public Subscriber(Stream body, TaskCompletionSource<bool> tcs)
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{
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this._writer = new StreamWriter(body);
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this._tcs = tcs;
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}
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public async void WriteAsync(string message)
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{
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try
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{
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_writer.Write(message);
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_writer.Flush();
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}
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catch (Exception e)
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{
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if (e.HResult == -2146232800) // non-existent connection
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_tcs.SetResult(true);
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else
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_tcs.SetException(e);
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}
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}
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}
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public class Api
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{
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System.Timers.Timer _timer = new System.Timers.Timer(500);
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List<Subscriber> _subscribers = new List<Subscriber>();
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public Api()
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{
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_timer.Elapsed += _timer_Elapsed;
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}
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void _timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
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{
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UpdateSubscribers();
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}
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public void UpdateSubscribers()
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{
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Console.WriteLine("updating {0} subscribers", _subscribers.Count);
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var subscribersCopy = _subscribers.ToList<Subscriber>();
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var msg = String.Format("Hello async at {0}\n", DateTime.Now);
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subscribersCopy.ForEach(w => w.WriteAsync(msg));
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_timer.Start();
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}
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public Task Invoke(IOwinContext context)
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{
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SetEventHeaders(context);
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System.IO.Stream responseStream = context.Environment["owin.ResponseBody"] as Stream;
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var tcs = new TaskCompletionSource<bool>();
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var s = CreateSubscriber(responseStream, tcs);
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tcs.Task.ContinueWith(_ => _subscribers.Remove(s));
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Console.WriteLine("Add subscriber. Now have {0}", _subscribers.Count);
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s.WriteAsync("Registered\n");
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_timer.Start();
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return tcs.Task;
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}
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private Subscriber CreateSubscriber(System.IO.Stream responseStream, TaskCompletionSource<bool> tcs)
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{
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var s = new Subscriber(responseStream, tcs);
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_subscribers.Add(s);
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return s;
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}
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private static void SetEventHeaders(IOwinContext context)
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{
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context.Response.ContentType = "text/eventstream";
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context.Response.Headers["Transfer-Encoding"] = "chunked";
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context.Response.Headers["cache-control"] = "no-cache";
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}
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}
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}
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}
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