MerrionComputing
Projections on demand
An intriguing side effect of the "a command or query instance is an entity with its own backing event stream" combined with "notifications are sent when an event is appended to an event stream" is that a projection request can be handled by an azure function spun up specifically for that purpose without the need for an orchestration.
This will allow projections to be executed as a "swarm"..
(This will also apply to classifiers which are, after all, just specialist projections )
Projection events are:
Projection Requested - when a command or query decides it needs a classifier done
Projection Result Returned - when the classifier result is returned to the command or query
This is going to need some way of new-ing up a projection instance from the projection type name as I don't want to use the CLR class names explicitly as that would lock-in the implementation to the data.
(No reason why someone might want to use a totally different technology to run projections on demand)