1. Event Scheduler
------------------
-> incomming event
   -> commands/${cmdSeq}-${eventMetadata} file with event metadata body created
# valid command sent / handling and event

2. Event Processor
------------------
-> event data from commands/${cmdSeq}-${eventMetadata} file read and event appended to event-log
   -> events/${evtSeq}-${eventType}-${eventAggId} file with event body created
      -> commands/${cmdSeq}-${eventMetadata} file removed
# event persisted

3. Event Handler
----------------
-> events/${evtSeq}-${eventType}-${eventAggId} file read with event metadata
   -> emit event if target subscribers found or create notify/... file
      -> events/${evtSeq}-${eventType}-${eventAggId} file removed
# subscribers notified