Event-driven design: The power of event notifications

This is the second part of a series on “Moving from RESTful to EVENTful.”
As I see more and more companies working to add event-driven, sometimes called “real-time,” APIs to their programs, I am noticing that there are common cases where an event style is favored over others. Using Martin Fowler’s names as a reference point, I’m noticing that event sourcing (ES) and command-query responsibility segregation (CQRS) are the most commonly discussed event styles right now.