A beginner here.
I've read through forums and the web but only able to understand persistence of MQTT at broker level, but what about persistence at device level?
How does MQTT deal with that? Do I need to build it myself?
Context - I need to count the number and frequency of people passing through a door. Every time someone passes through the device, it sends a message to a server and stores in a database.
But what if there is no connection between the server and device?
How can I store all the messages at device level till it is sent to the server.
The problem here is not just sending the updated payload but also the time and counting the number of messages.