Wow. Everything old is new again. I built a business state machine for a bespoke application using Oracle 8i and their stateful queues back in 2005. I had re-architected a batch-driven application (which couldn't scale temporally i.e. we had a bunch of CPU sitting near idle for a lot of the time), and turned it into an event driven solution. CPU usage became almost a horizontal line, saving us lots of money as we scaled (for the record, "scale" for this solution was writing 5M records a day into a partitioned table where we kept 13 months of data online, and then billed on it). Durable execution was just one of the many benefits we got out of this architecture. Love it.