This topic provides answers to some commonly asked questions about the features of ApsaraMQ for MQTT.
What is the maximum retention period for offline messages?
Three days.
ApsaraMQ for MQTT retains offline messages only when the QoS parameter is set to 1 and the cleanSession parameter is set to false. Offline messages can be retained for up to three days and are automatically deleted after this period elapses.
You can customize the maximum retention period for offline messages in an Enterprise Platinum Edition instance. To do so, contact ApsaraMQ for MQTT technical support.
When does the broker push offline messages?
The broker starts pushing offline messages after the broker detects that the client is online.
What is a suitable keepalive time that can be specified?
We recommend that you set the keepalive time to the default value in ApsaraMQ for MQTT: 90 seconds.
Does Message Queue for MQTT support will and retained messages?
No, Message Queue for MQTT does not support will and retained messages.
Are topics automatically deleted if they are not used for a long period of time?
No, topics are not automatically deleted.
ApsaraMQ for MQTT does not automatically delete the topics and group IDs that are created unless your instance is released after expiration.
Can I configure the endpoint of Message Queue for MQTT to an IP address?
No, you cannot configure the endpoint of Message Queue for MQTT to an IP address.
Use a domain name to access the ApsaraMQ for MQTT broker. An IP address is dynamic and may cause connection failures.
Does ApsaraMQ for MQTT support the clustering consumption mode?
The clustering consumption mode is supported by the client SDK but not the cloud SDK. You can use the client SDK to send messages and use the cloud SDK to subscribe to messages.
The cloud SDK is suitable for scenarios in which cloud applications need to be integrated. For more information, see Overview.
Does ApsaraMQ for MQTT support the configuration of other alert recipients?
Message Queue for MQTT uses the monitoring and alerting feature to send notifications to the mobile number that is bound to your Alibaba Cloud account. You cannot change this number to the mobile number of another recipient.
Does ApsaraMQ for MQTT support the migration of instances across Alibaba Cloud accounts?
No, Message Queue for MQTT does not support the migration of instances across Alibaba Cloud accounts.