Lightbend Academy is free (for a while)

https://academy.lightbend.com/

I've been curiously monitoring the whole reactive architecture development over the past five years or so. I haven't had a significant business case to pivot on technologies, but now I can at least get more familiar and experienced through this excellent online program.

Specifically, I'm keen to learn better ways to apply Domain-Driven Design principles, CQRS, Event Sourcing, and Actor Model patterns to achieve high-availability and resiliancy to software systems at scale.