/// <summary>
/// Unsubscribe for message topics
/// </summary>
/// <param name="topics">List of topics to unsubscribe</param>
/// <returns>Message Id in UNSUBACK message from broker</returns>
public ushort Unsubscribe(string[] topics)
{
int attempts = 0;
bool acknowledged = false;
MqttMsgUnsubscribe unsubscribe =
new MqttMsgUnsubscribe(topics);
MqttMsgUnsuback unsuback = null;
do
{
try
{
// try unsubscribe
unsuback = (MqttMsgUnsuback)this.SendReceive(unsubscribe.GetBytes());
acknowledged = true;
}
catch (MqttTimeoutException)
{
// no UNSUBACK message received in time, retry with duplicate flag
attempts++;
unsubscribe.DupFlag = true;
// delay before retry
if (attempts < MQTT_ATTEMPTS_RETRY)
Thread.Sleep(MQTT_DELAY_RETRY);
}
} while ((attempts < MQTT_ATTEMPTS_RETRY) && !acknowledged);
// return message id from SUBACK or zero (no message id)
return acknowledged ? unsuback.MessageId : (ushort)0;
}
