Domoticz

I have two Raspberry's. Both with Domoticz. One as master and one as slave configured.
They do communicate with each other.
Now I want to make a switch on both of them, that will tricker when the other domoticz is offline/online.
I had a look at Http/https poller, but I do no understand how this would work for me.
Has anyone creates such a switch? And how do I configure this?

Share a sensor to each other that is updated regularly, f.i. the cpu load.
Then create a notification on that sensor when last update is greater than x minutes.

Or in case you would like to have a separate switch, test for the last update and trigger the switch from script.

That is a good solution.
I will try that out