as it turns out, we can always trigger commands right away,
the moment all arguments are known. Thus it is sufficient to
send a single argument binding message, which allows us to
get rid of a lot or ugly complexities (payload visitor).
after reading some related code, I am leaning towards a design
to mirror the way command messages are sent over the UI-Bus.
Unfortunately this pretty much abandons the possibility to
invoke these operations from a client written in C or any
other hand made language binding. Which pretty much confirms
my initial reservation towards such an excessively open
and generic interface system.
...the sheer amount of mechanical replacements scattered all over these
files might be a vivid indication, that the design of the interface system
is subobptimal ;-)