Building distributed systems is hard. When you’re working with applications that span a planet, the speed of light is a brake on what you want to do, complicating data replication among servers and services. Someone buys a widget in Hong Kong at almost the same time as someone in Paris, but there’s only one in stock. How do you know who to bill, and who to tell the purchase failed? Whose purchase ends up being the one recorded in your line-of-business tools?
