Chapter · MQTT
Sorting and keeping
A whole room or a whole house with one subscription, and the last letter kept for whoever connects late.
- 04Wildcards4 minA subscription can be a filter rather than one topic. Plus stands for exactly one level and hash for everything below, so a room or a whole house is one subscription — if the topics were named for it.
- 05Retained messages4 minA broker forgets a message once it has passed it on, so a phone that opens late shows a dash. Post with the retain flag and the broker keeps the last one for each topic, and hands it over the moment someone subscribes.
Start at 04 and read down — the order is the order things get easier in. Or take the one with your part in it; every article stands on its own, and links back to whatever it needs.