Erlang in Practice Episode 8: OTP Supervisor and Application Behaviors

In this final episode, we’ll focus on two mechanisms that OTP provides to manage the lifecycle of processes in an application: supervisor and application behaviors. We’ll write a Web Supervisor and a Messaging Supervisor to manage those subsystems, and then layer another meta-supervisor on top to manage the entire chat system. You’ll learn how to:

• implement an OTP Supervisor behavior to start, stop, and monitor worker processes
• write child process specifications
• handle messages sent from monitored processes
• nest supervisors into hierarchies of supervision for better process management
• implement an OTP Application behavior to easily start-up and gracefully shutdown an entire application
• refactor existing code to be supervisor-friendly
• a trick for starting Erlang systems from shell scripts, such as Unix init scripts