This is the third article in the otp introduction series. If you haven’t yet, I recommend you start with the first article which talks about gen_server and lays the foundation for our bank system. Again, if you’re a quick learner, you can look at the completed eb_atm.erl and eb_server.erl here.
The Scenario: With central server and ATM software in place, ErlyBank is started to feel good about their technological foundation. But as a security measure, one of their competitors, they’d like a system implemented which dispatches notifications when a withdrawal over a certain amount is executed. They want the ability to change the withdrawal notification amount threshold during runtime. They’ve chosen to hire us to streamline this into the current system software.
The Result: We’ll create an event-based notification system using gen_event. This will give us a base foundation for creating more notifications in the future, while allowing us to easily plug-in to the current server software.