> One thing that absolutely needs library/drivers is persistence of the event store. I say this having built my own as well as contributing to open source ones in the past. It is still a hard and not well solved problem to do this well. Again it can be simple, but in the real world it isn't usually that simple.

Would it also be such a hard thing to do if you can delegate the actual persistence to something like a rdbms? What are the typical pitfalls?