A couple of years ago, I interviewed for a Bay Area company that provided me with a great programming problem that I've been using for years to prototype with n

A couple of years ago, I interviewed for a Bay Area company that provided me with a great programming problem that I've been using for years to prototype with new languages. Write a Rate Counting Proxy Service for a REST API that does the following: * Stores state of requesting IP and a count of API calls made. * Makes appropriate tradeoffs to limit I/O per request. * Highly concurrent * Maintains counts offline when shutting down/starting up. I was asked to do the assignment in Java, despite not really knowing a lot of Java. It was a fun weekend project and I've continued to use it as a good "learning project" in other languages.