Refactoring the view building code

Hopefully, at this point, you have a pretty good understanding of what you can do with Akka Streams. It's a pretty big topic, certainly enough to fill a book on it's own. I've tried to cover all of the areas that I thought were important for someone who was learning Akka Streams for the first time. Armed with that knowledge, we can now take care of some unfinished business, which was leftover from Chapter 5, Separating Concerns with CQRS.

When we built out the ViewBuilder framework in Chapter 5, Separating Concerns with CQRS, we had the source from our eventsByTag query essentially piping the events back to itself and then processing them as if they were regular inbound actor messages. This works, and it's pretty simple, but you won't get any of the benefits of back-pressure handling. The actor that receives the messages will dequeue events as fast as possible, which can possibly lead to memory issues with its mailbox. Also, whatever is happening downstream...