Here at Ably, we deal with hard engineering problems all the time and pushing at the edges often results in us running up against all sorts of interesting gotchas. We recently made some AWS NLBs fall over, and had a hazardous encounter with Cassandra counter columns. In our day-to-day, we use gRPC for fast and efficient data exchange with mutual client/server state synchronization.

Everything that occurs is a change in state, or an event for short: the sun comes out, the bus arrives, plants emerge from the ground, a neighbor says hello, the calendar page turns to a certain date or time, or your team lead yells that you should get to da choppa. Among all events, the ones that must be observed, recorded, or otherwise acted upon can be categorized based on how timely the reaction needs to be.

In this post, we take a look at 5 pub/sub examples that will help us understand how companies and organizations across all types of industries are leveraging this architectural design pattern to solve common engineering challenges and improve their architecture.