If I may harken back to my initial disclaimer, namely, that I’m not an Internet programmer, I wish to say that in 1988 (in an aerospace venue) I urged my employer to purchase Harel’s StateMate tool. The proverbial bean counters did their job in rejecting the request. I’m happy to see this excellent book’s arrival, along with its open-source superstructure. It is very much worth reading, both for theory and for real-world application to complex event-driven systems.