maybe you can work from that then?

In the case of the z-way-server, if you poll the server at regular intervals, you'll find all wake notification's in there.

Direct valve control is achieved by setting the thermostatMode to 31. Then you can set the switch level to put the valve at the desired opening. As the StellaZ is a battery operated device, there's no point at all in polling it whilst its asleep, so look for device wake notifications and initiate ...

I've got 12 of the StellaZ on my install and i've used them in direct position control (via a virtual thermostat) and more recently, self regulation via set point control.

Both work well, but direct position control is more accurate and you can use alternative temperature feedback.