MQTT Client Connectivity with .Net

mqttClient.UseDisconnectedHandler(async e =>
{
Console.WriteLine("Disconnected from MQTT broker.");
// Optionally, handle reconnection logic here
});
await mqttClient.DisconnectAsync();

using System;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using MQTTnet;
using MQTTnet.Client
class Program
{
static async Task Main(string[] args)
{
// Load the root certificate
//var rootCert = new X509Certificate2("path_of_the_root_file");
// Configure MQTT client options
var options = new MqttClientOptionsBuilder()
.WithClientId(GenerateClientId("crystalmq_",10))
.WithTcpServer("public-mqtt-broker.bevywise.com", 1883) // Enable TLS change port 8883
//.WithWebSocketServer("ws://public-mqtt-broker.bevywise.com:10443/mqtt") // Use WebSocket server URI and Enable TLS change port 11443
// .WithCredentials("username", "password") // Add username and password
//
// .WithTls(new MqttClientOptionsBuilderTlsParameters
// {
// UseTls = true,
// Certificates = new List { rootCert },
// AllowUntrustedCertificates = true, // Disable certificate chain validation
// IgnoreCertificateChainErrors = true, // Ignore certificate chain errors
// IgnoreCertificateRevocationErrors = true // Ignore certificate revocation errors
// })
.Build();
// Create MQTT client
var factory = new MqttFactory();
var mqttClient = factory.CreateMqttClient();
// Handle client events
mqttClient.ConnectedAsync += async e =>
{
Console.WriteLine("Connected successfully with MQTT Broker.");
// Subscribe to a topic
await mqttClient.SubscribeAsync(new MqttClientSubscribeOptionsBuilder().WithTopicFilter(f => f.WithTopic("cmq/topic")).Build());
Console.WriteLine("Subscribed to topic.");
// Publish a message
var message = new MqttApplicationMessageBuilder()
.WithTopic("cmq/topic")
.WithPayload("Hello CrystalMQ")
.Build();
await mqttClient.PublishAsync(message);
Console.WriteLine("Message published.");
};
mqttClient.DisconnectedAsync += async e =>
{
Console.WriteLine("Disconnected from MQTT Broker.");
await Task.Delay(TimeSpan.FromSeconds(5));
try
{
await mqttClient.ConnectAsync(options);
}
catch
{
Console.WriteLine("Reconnecting failed.");
}
};
mqttClient.ApplicationMessageReceivedAsync += e =>
{ Console.WriteLine($"Received message: {System.Text.Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
return Task.CompletedTask;
};
// Connect to the MQTT broker
await mqttClient.ConnectAsync(options);
// Keep the application running
Console.WriteLine("Press key to exit");
Console.ReadLine();
private static string GenerateClientId(string prefix, int length)
{
const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
var random = new Random();
var randomChars = new char[length];
for (int i = 0; i < length; i++)
{
randomChars[i] = chars[random.Next(chars.Length)];
}
return prefix + new string(randomChars);
}
}

using System;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using MQTTnet;
using MQTTnet.Client;
class Program
{
static async Task Main(string[] args)
{
var options = new MqttClientOptionsBuilder()
.WithClientId(GenerateClientId("crystalmq_",10))
.WithTcpServer("public-mqtt-broker.bevywise.com", 1883)
//.WithWebSocketServer("ws://public-mqtt-broker.bevywise.com:10443/mqtt")
// .WithCredentials("username", "password") // Add username and password
.WithProtocolVersion(MQTTnet.Formatter.MqttProtocolVersion.V500) //if you use mqtt version 5. note: TLS enable is not support version 5
.Build();
// Create MQTT client
var factory = new MqttFactory();
var mqttClient = factory.CreateMqttClient();
// Handle client events
mqttClient.ConnectedAsync += async e =>
{
Console.WriteLine("Connected successfully with MQTT Broker.");
// Subscribe to a topic
await mqttClient.SubscribeAsync(new MqttClientSubscribeOptionsBuilder().WithTopicFilter(f => f.WithTopic("cmq/topic")).Build());
Console.WriteLine("Subscribed to topic.");
// Publish a message
var message = new MqttApplicationMessageBuilder()
.WithTopic("cmq/topic")
.WithPayload("Hello CMQ")
.WithQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.ExactlyOnce)
.WithRetainFlag(true)
.Build();
await mqttClient.PublishAsync(message);
Console.WriteLine("Message published.");
};
mqttClient.DisconnectedAsync += async e =>
{ Console.WriteLine("Disconnected from MQTT Broker.");
await Task.Delay(TimeSpan.FromSeconds(5));
try
{
await mqttClient.ConnectAsync(options);
}
catch
{
Console.WriteLine("Reconnecting failed.");
}
};
mqttClient.ApplicationMessageReceivedAsync += e =>
{
Console.WriteLine($"Received message: {System.Text.Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
return Task.CompletedTask;
};
// Connect to the MQTT broker
await mqttClient.ConnectAsync(options);
// Keep the application running
Console.WriteLine("Press key to exit");
Console.ReadLine();
private static string GenerateClientId(string prefix, int length)
{
const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
var random = new Random();
var randomChars = new char[length];
for (int i = 0; i < length; i++)
{
randomChars[i] = chars[random.Next(chars.Length)];
}
return prefix + new string(randomChars);
}
}

dotnet run

dotnet build