Signlar client not executing connection.on method - signalr

Question

I have a Signaler client in worker service. developed Signaler server in .net core web API.
Here everything is working but when I am calling.
await _hub.Clients.All.SendAsync("calldscclient", desUserList.FirstOrDefault().DscConnectionId);
From the server, it's not sending a message to the client
connection.On<string>("calldscclient", (message) => {}
I am writing my client code here.
using Microsoft.AspNetCore.SignalR.Client;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using WorkerService1.Properties;
namespace WorkerService1
{
public class Worker : BackgroundService
{
private readonly ILogger<Worker> _logger;
public Worker(ILogger<Worker> logger)
{
_logger = logger;
}
public HubConnection connection;
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
//while (!stoppingToken.IsCancellationRequested)
{
using (StreamWriter writer = new
StreamWriter(#"C:\Users\devma\source\repos\WorkerService1\WorkerService1\TextFile1.txt"))
{
writer.WriteLine("bigin");
}
var ip = GetLocalIPAddress();
ip = "localhost";
connection = new HubConnectionBuilder()
//.WithUrl(new Uri("https://localhost:5001/dschub"))
//.WithAutomaticReconnect(new RandomRetryPolicy())
//.Build();
.WithUrl("https://localhost:44339/dschub"
,
options =>
{
options.WebSocketConfiguration = conf =>
{
conf.RemoteCertificateValidationCallback = (message, cert, chain, errors) =>
{ return true; };
};
options.HttpMessageHandlerFactory = factory => new HttpClientHandler
{
ServerCertificateCustomValidationCallback = (message, cert, chain, errors) =>
{ return true; }
};
}
)
.Build();
await connection.StartAsync();
await connection.InvokeAsync("dscRegister", ip);
connection.On<string>("calldscclient", (message) =>
{
using (StreamWriter writer = new
StreamWriter(#"C:\Users\devma\source\repos\WorkerService1\WorkerService1\TextFile1.txt"))
{
writer.WriteLine("Monica Rathbun");
}
});
}
}
public static string GetLocalIPAddress()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
return ip.ToString();
}
}
throw new Exception("No network adapters with an IPv4 address in the system!");
}
}
}
For calling
connection.On<string>("calldscclient", (message) => {}
I am using web API on the server.
My WebAPI code is here.
[HttpGet("servedsc")]
public async Task<ActionResult> ServeDsc()
{
var remoteIpAddress = HttpContext.Request.Host.Host;
var desUserList = await _dscService.GetDscUser(remoteIpAddress);
await _hub.Clients.All.SendAsync("calldscclient",
desUserList.FirstOrDefault().DscConnectionId);
//await
_hub.Clients.User(desUserList.FirstOrDefault().DscConnectionId).SendAsync("calldscclient");
return Ok(desUserList);
}
Here everything is working fine like Signaler Hub is executing property when the client making a connection.
But the problem is when the server is sending messages to the client it's not getting.

Answer 1

You should generally register your .On method handlers before starting the connection. In your case, you're awaiting InvokeAsync which will invoke the server method and wait for the server method to finish. Then you are registering your .On method which will be too late at that point.