SignalR and remote component TCP port

[dtramzter]

I need help. I have a remote component that transmits data to me via TCP through a port (GPS).
in my blazor server app
Program.cs -->
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSignalR();

var app = builder.Build();
app.MapHub("/current-time");

app.Run("http://*:5000");

MainBub.cs --->
using Microsoft.AspNetCore.SignalR;

public class MainHub : Hub
{
public async IAsyncEnumerable Streaming(CancellationToken cancellationToken)
{
while (true)
{
yield return DateTime.UtcNow ;
await Task.Delay(1000, cancellationToken);
}
}
}
To know if the server was working, create a client and with it it works fine
from client side --->

using Microsoft.AspNetCore.SignalR.Client;

public class MainClient
{
public static async Task ExecuteAsync()
{

var uri = "https://localhost:5000/current-time";

await using var connection = new HubConnectionBuilder().WithUrl(uri).Build();

await connection.StartAsync();

await foreach (var date in connection.StreamAsync("Streaming"))
{
Console.WriteLine(date);
}
}
}

But the remote component (GPS) doesn't connect to the server.

Remote component data (GPS)
Domain: XXX,XX.XXX.XXX
Port: 5000
Protocol: TCP

What am I doing wrong?

[engineering87]

Hi there,
your GPS component speaks raw TCP, while SignalR is not raw TCP. Your GPS device is trying to connect to a TCP socket at port 5000, expecting to just send/receive raw data. But your Blazor app is not exposing a raw TCP socket, it’s exposing a SignalR endpoint on that port, which has a completely different protocol.
You can try to build a raw TCP listener in Blazor App, something like this:

public class GpsListenerService : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        TcpListener listener = new TcpListener(IPAddress.Any, 5001); // use a different port
        listener.Start();

        while (!stoppingToken.IsCancellationRequested)
        {
            var client = await listener.AcceptTcpClientAsync(stoppingToken);
            _ = HandleClientAsync(client, stoppingToken);
        }
    }

    private async Task HandleClientAsync(TcpClient client, CancellationToken token)
    {
        using var stream = client.GetStream();
        using var reader = new StreamReader(stream);

        while (!token.IsCancellationRequested && client.Connected)
        {
            var line = await reader.ReadLineAsync();
            Console.WriteLine($"GPS Data: {line}");
        }
    }
}

Remeber to register the listener:

builder.Services.AddHostedService<GpsListenerService>();

[BrennanConroy]

You can bind a SignalR endpoint to TCP, see the example:
https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/samples/SignalRSamples/Program.cs#L35-L39

But your GPS client still needs to speak the "SignalR protocol" https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/docs/specs/HubProtocol.md