//Параметры подключения
var option = new MQTT.MQTTClientOption()
{
    ClientId = this.txtClientId.Text,
    IpString = this.txtServer.Text,
    Port = Convert.ToInt32(this.txtPort.Text),
    UserName = this.txtUserName.Text,Пароль = this.txtPassword.Text
};
//Пример клиента
this.mqttClient = новый MQTT.MQTTClient();
this.mqttClient.ClientReceived += MqttClient_ClientReceived;
var result = await this.mqttClient.ConnectAsync(опция);
если (результат.Состояние == ложь)
{
    MessageBox.Show(result.Fail, "намекать", MessageBoxButtons.OK, MessageBoxIcon.Warning);
    return;
}
//Начинаем получать
this.mqttClient.BeginReceive();

private short _PacketId = 1;
private async void BtnPublish_Click(object sender, EventArgs e)
{
    this.btnPublish.Enabled = false;
    this.Cursor = Cursors.WaitCursor;
    try
    {
        short qos = 0;
        if (rdbLevel1.Checked)
            qos = 1;
        if (rdbLevel2.Checked)
            qos = 2;
        
        var data = new MQTT.PublishEntity()
        {
            Topic = this.txtTopic.Text,
            Reload = System.Text.Encoding.UTF8.GetBytes(this.txtContent.Text),
            Qos = qos,
            PacketId=_PacketId
        };
        var result = await this.mqttClient.PublishAsync(data,false);
        if(result.State == false)
        {
            this.AppendText("Отправка не удалась:" + result.Fail);
            return;
        }
        this._PacketId++;
        this.AppendText("Отправлено успешно, вернуть результат:" + result.Result);
    }
    finally
    {
        this.btnPublish.Enabled = true;
        this.Cursor = Cursors.Default;
    }
}

private async void BtnSubscribe_Click(object sender, EventArgs e)
{
    this.btnSubscribe.Enabled = false;
    this.Cursor = Cursors.WaitCursor;
   
    try
    {
        string fail = string.Empty;

        short qos = 0;
        if (rdbQos1.Checked)
            qos = 1;
        if (rdbQos2.Checked)
            qos = 2;

        MQTT.SubscribeEntity entity = new MQTT.SubscribeEntity();
        entity.Filter = this.txtFilter.Text;
        entity.Qos = qos;

        this.AppendText("Начать подписку...");
        //if (mqttClient.Subscribe(this.txtFilter.Text, qos, out result, out fail) == false)
        //{
        //    this.AppendText(fail);
        //    return;
        //}
        var result = await mqttClient.SubscribeAsync(entity.Filter,entity.Qos);
        if (result.State == false)
        {
            this.AppendText(result.Fail);
            return;
        }
       
        this.AppendText("Подписка прошла успешно! Возвращаемый результат:" + result.Result);
        MQTT.SubscribeHelper.Save(entity);

        DataRow drData = this.dtSubscribes.NewRow();
        drData["Id"] = entity.Id;
        drData["Filter"] = entity.Filter;
        drData["Qos"] = entity.Qos;
        drData["Count"] = 0;
        dtSubscribes.Rows.Add(drData);
    }
    finally
    {
        this.btnSubscribe.Enabled = true;
        this.Cursor = Cursors.Default;
    }
}

private async void DataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
    if (this.dataGridView1.CurrentCell == null)
        return;

    DataRowView drv = this.dataGridView1.CurrentRow.DataBoundItem as DataRowView;
    if (drv == null)
        return;

    if (MessageBox.Show("Подтвердите отмену текущего выбора:" + drv["Filter"].ToString() + " подписка?", "подтверждать", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) != DialogResult.OK)
        return;
    try
    {
        this.AppendText("Начать отписываться...");
        var result = await mqttClient.UnSubscribeAsync(drv["Filter"].ToString());
        if (result.State == false)
        {
            this.AppendText(result.Fail);
            return;
        }
        this.AppendText("Отписка прошла успешно! Результат возврата:" + result.Result);
        MQTT.SubscribeHelper.Delete(drv["Id"].ToString());
        this.dataGridView1.Rows.RemoveAt(this.dataGridView1.CurrentCell.RowIndex);
    }
    catch (Exception ex)
    {
        this.AppendText("Исключение отписки:" + ex.ToString());
    }

}

private void MqttClient_ClientReceived(MQTT.MQTTClient client, MQTT.ReceiveResult receive)
{
    if(receive.Data != null)
        this.AppendText("DataReceived state="+receive.State+" topic="+ receive.Data.Topic + " content=" + System.Text.Encoding.UTF8.GetString(receive.Data.Reload));
    else if(receive.State)
        this.AppendText("DataReceived state=" + receive.State + " result=" + receive.Result);
    else
        this.AppendText("DataReceived state=" + receive.State + " fail=" + receive.Fail);
}