FAQ

What is the relationship between topic and sub in a message queue?

A：Topic is a queue entity, which can be understood as a repository of cached data. Only after data timeout or when the repository is full will the data be discarded. sub can be understood as a message broker, which is responsible for replicating copies of data from the repository and sending them to clients who have created subscriptions through MQTT.

Why is the client unable to receive data after abnormal disconnect and reconnect?

A：The service supports users to connect and consume data via MQTT, and the client can receive messages only after subscription. Since session is not supported at present, the subscription system on the client side will not be saved. When the client disconnects, the subscription will be cleared. After reconnect, the client can create the subscription again and thus consume data.

Is one-way or two-way TLS authentication supported?

A：One-way TLS authentication is supported. A .pem certificate available for download is used for the client to verify the legitimacy of the server. The server verifies the client’s legitimacy with username and password when MQTT is connected.

How can I get more help?

A：If you have encounter problems using this service, please join the technical support QQ group: 626384429.