NB: I'm not sure if this an MC issue or a jremote issue or both, I suspect it is an MC issue because of the MCWS response hence posting in this forum.
JRemote has an option for "app follows server zone" which allows jremote to track the active zone. This seems like it should allow jremote to consistently work as a volume control for a system using internal volume however it doesn't when that system uses the WDM driver as the active zone is not updated when the wdm driver fires up. It behaves more like the active zone is the zone a user last played something to.
To reproduce in my system, I can do the following;
configure 2 zones, say music and wdm
configure jremote to follow the active zone
add exclusive zoneswitch rules so library content goes to music and the wdm driver goes to the wdm zone
play something from the library, music zone is activated
goto
http://mc:port/MCWS/v1/Playback/Zones and check which zone is active (Item.@name="CurrentZoneID" should point to the id of the music zone)
check jremote, it should be tracking the music zone
stop playback
play something on the PC which activates the WDM zone
goto
http://mc:port/MCWS/v1/Playback/Zones , the CurrentZoneID has not updated
check jremote, it is still on the music zone
I would have thought the active zone should update when the WDM driver fires up.
I'm not entirely sure what the active zone means if you allow multiple active zones (e.g. if you have multiple physical output devices) though albeit that seems like a side effect of the zones for DSP config vs zones for physical output issue.
user impact = difficult to find a reliable way (for a non technical user at least) to use the volume control