C# Dotnet SSE Server antwortet, aber der Browser zeigt die Nachrichten nicht an. Warum?

Anonymous · Post by **Anonymous** » 03 Jun 2025, 11:40

Ich habe einen SSE -Server mit den folgenden Einstellungen/Anforderungen:

[*] c# dotnet 8
[*] Nicht blockierende Kommunikation
[*] nein ASP

; /> Auf der anderen Seite (Client) habe ich einen Browser mit JavaScript < /p>
Das Problem: < /p>

Ich kann die Kommunikation vom Client zum Server an den erhaltenen Paket mit dem Kunde an den Client verpflichten. Das JavaScript antwortet jedoch nicht auf die empfangenen Pakete. Nach kurzer Zeit die zwischengespeicherten Pakete (viele Pakete). Aber ich denke, der Cache ist voll und ich sehe den Cache.

Code: Select all

using System;
using System.Collections.Generic;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Timers;

class Program
{
private static readonly List clients = new List();
private static readonly object lockObject = new object();
private static System.Timers.Timer? messageTimer;

static async Task Main(string[] args)
{
string url = "http://+:5000/";
HttpListener listener = new HttpListener();
listener.Prefixes.Add(url);
listener.Start();
Console.WriteLine($"Server runs on {url}");

// Timer
messageTimer = new System.Timers.Timer(1000);
messageTimer.Elapsed += SendPeriodicMessages;
messageTimer.AutoReset = true;
messageTimer.Enabled = true;

while (true)
{
HttpListenerContext context = await listener.GetContextAsync();
HandleClient(context);
}
}

private static void HandleClient(HttpListenerContext context)
{
HttpListenerRequest request = context.Request;
HttpListenerResponse response = context.Response;

response.Headers.Add("Access-Control-Allow-Origin", "*");
response.Headers.Add("Access-Control-Allow-Methods", "GET, OPTIONS");
response.Headers.Add("Access-Control-Allow-Headers", "Content-Type");

if (request.HttpMethod == "OPTIONS")
{
response.Headers.Add("Access-Control-Allow-Origin", "*");
response.Headers.Add("Access-Control-Allow-Methods", "GET, OPTIONS");
response.Headers.Add("Access-Control-Allow-Headers", "Content-Type");
response.StatusCode = (int)HttpStatusCode.OK;
response.OutputStream.Close();
return;
}

response.Headers.Add("Content-Type", "text/event-stream");
response.Headers.Add("Cache-Control", "no-cache");
response.Headers.Add("Connection", "keep-alive");

AddClient(context);
}

private static void AddClient(HttpListenerContext context)
{
lock (lockObject)
{
clients.Add(context);

var clientIp = context.Request.RemoteEndPoint.Address.ToString();
var clientPort = context.Request.RemoteEndPoint.Port;
Console.WriteLine($"Client connected: IP = {clientIp}, Port = {clientPort}");
}
}

static int TimerCounter = 0;
private static void SendPeriodicMessages(object? sender, ElapsedEventArgs e)
{
Console.WriteLine("TimerTick " + TimerCounter);
SendMessagesToClients("data: " + TimerCounter++ + "\\n\\n");
}

private static void SendMessagesToClients(string message)
{
Task.Run(async () =>
{
byte[] buffer = Encoding.UTF8.GetBytes(message);

List sendTasks = new List();
List removeList = new ();

lock (lockObject)
{
Console.WriteLine("Number of Clients: "  + clients.Count);
foreach (var client in clients)
{
sendTasks.Add(Task.Run(() =>
{
try
{
HttpListenerRequest request = client.Request;
HttpListenerResponse response = client.Response;

var clientIp = client.Request.RemoteEndPoint.Address.ToString();
var clientPort = client.Request.RemoteEndPoint.Port;
Console.WriteLine($"Sending Data ({buffer.Length}) to {clientIp}:{clientPort}");

response.OutputStream.Write(buffer, 0, buffer.Length);
response.OutputStream.Flush();
}
catch (Exception ex)
{
Console.WriteLine($"Error - Cant send data to Client: {ex.Message}");
removeList.Add(client);
}
}));
}
}

await Task.WhenAll(sendTasks);

lock (lockObject)
{
while (removeList.Count > 0)
{
clients.Remove(removeList.First());
removeList.RemoveAt(0);
}
}
});
}
}
< /code>
und JavaScript: < /p>






TEST



Server Send Event



const eventSource = new EventSource('http://192.168.56.245:5000/');

eventSource.onmessage = function(event) {
const messagesDiv = document.getElementById('messages');
messagesDiv.innerHTML += `
${event.data}
`;
console.log(event.data);
};

eventSource.onerror = function(event) {
console.error("Error receiving messages from SSE:", event);
eventSource.close();
};



< /code>
Hier ist die Antwort aus der Curl: < /p>
*   Trying 192.168.56.245:5000...
* Connected to 192.168.56.245 (192.168.56.245) port 5000
> GET / HTTP/1.1
> Host: 192.168.56.245:5000
> User-Agent: curl/8.5.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Methods: GET, OPTIONS
< Access-Control-Allow-Headers: Content-Type
< Content-Type: text/event-stream
< Cache-Control: no-cache
< Connection: keep-alive
< Server: Microsoft-NetCore/2.0
< Date: Mon, 02 Jun 2025 07:32:14 GMT
< Transfer-Encoding: chunked
<
data: 351\n\ndata: 352\n\ndata: 353\n\ndata: 354\n\ndata: 355\n\ndata: 356\n\ndata: 357\n\ndata: 358\n\ndata: 359\n\ndata: 360\n\ndata: 361\n\ndata: 362\n\ndata: 363\n\ndata: 364\n\ndata: 365\n\ndata: 366\n\ndata: 367\n\ndata: 368\n\ndata: 369\n\ndata: 370\n\ndata: 371\n\ndata: 372\n\ndata: 373\n\ndata: 374\n\ndata: 375\n\ndata: 376\n\ndata: 377\n\ndata: 378\n\ndata: 379\n\ndata: 380\n\ndata: 381\n\ndata: 382\n\ndata: 383\n\ndata: 384\n\ndata: 385\n\ndata: 386\n\ndata: 387\n\ndata: 388\n\ndata: 389\n\ndata: 390\n\ndata: 391\n\ndata: 392\n\ndata: 393\n\ndata: 394\n\ndata: 395\n\ndata: 396\n\ndata: 397\n\ndata: 398\n\ndata: 399\n\ndata: 400\n\ndata: 401\n\ndata: 402\n\ndata: 403\n\ndata: 404\n\ndata: 405\n\ndata: 406\n\ndata: 407\n\ndata: 408\n\ndata: 409\n\ndata: 410\n\ndata: 411\n\ndata: 412\n\ndata: 413\n\ndata: 414\n\ndata: 415\n\ndata: 416\n\ndata: 417\n\ndata: 418\n\ndata: 419\n\ndata: 420\n\ndata: 421\n\ndata: 422\n\ndata: 423\n\ndata: 424\n\ndata: 425\n\ndata: 426\n\ndata: 427\n\ndata: 428\n\ndata: 429\

C# Dotnet SSE Server antwortet, aber der Browser zeigt die Nachrichten nicht an. Warum?

C# Dotnet SSE Server antwortet, aber der Browser zeigt die Nachrichten nicht an. Warum? ⇐ C#

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