SignalR

Program

builder.Services.AddSignalR();

app.MapHub<HealthCheckHub>("/api/health-hub");

Hub

public class HealthCheckHub : Hub
{
    
}

HubController

[ApiController]
[Route("api/[controller]/[action]")]
public class BroadcastController : ControllerBase
{
    private IHubContext<HealthCheckHub> _hub;
    public BroadcastController(
        IHubContext<HealthCheckHub> hub
    )
    {
        _hub = hub;
    }
    [HttpGet]
    public async Task<IActionResult> Update()
    {
        await _hub.Clients.All.SendAsync("Update", "test");
        return Ok("Update message sent.");
    }
}