Re: [mosquitto-dev] Info about V5 implementation ?

[Dustin Sallings <dustin@xxxxxxx>]

On Sat, Oct 19, 2019 at 10:57 AM Carlos G Mendioroz <tron@xxxxxxx> wrote:

MQTT v5 seems a perfect fit to have a TTL value for measurements. 60
minutes old temp has no longer value as actual state. In fact, it makes
a lot easier to trigger alarms when is self evident that a sensor is not
alive. (I'm generating virtual alive data by a phantom topic with
timestamp for the time being).

I do something similar -- most of my publishers are using MQTT v5 with expiries.

 

So when looking at v5 I have been unable to find documentation that
shows things like:
-can I run -V 5 and still connect via 3.1.1 clients ?
-can I have different listeners for different protocols ?
-is there a way to migrate without "D" day ?

mosquitto happily supports interoperability between both as much as is sensible.  Obviously your expiries are lost on the 3.1.1 clients, but the broker should still honor them (± bugs).

I still do have a few 3.1.1 clients (including a dashboard I use on Android regularly).  On the wire, the 3.1.1 data is mostly just a subset of the 5.0 data.