Data access policies
- guaranteed delivery of all events in the pool
- hold off the input if it cannot keep up with the data flow.
- give me events as fast as possible, but not necessarily all of them
- must allow to “skip” events
- split a stream over more than one consumer
- each event is deliverd to only one consumer (load balancing)
- even in a shared stream, certain administrative-type events can still be sent to all consumers (begin-run, etc)