TODO:
X Get more knowledge about the Reactor front ends.
X Throw up some examples in some slides (#5).
X Add a section at the end to get out of the weeds and put a bit ol' bow on it.

Topics:

1. Evolution of event-driven programming:
X Wait for a key press or line of text.
X Interrupts (hardware and software).
X Modern event loops

2. Types of events in modern applications:
X IO
X Timer
X User input
X Signal
X Anything that can spontaneously happen in the real world.

3. How to write a modern event-loop (reactor style).
X kernel facilities (poll, select, etc.)

4. List of already-built reactors.
X EV
X Glib
X ...

5. Event-driven programming in Perl
X AnyEvent
X IO::Async
X Mojo::IOLoop
X POE

6. Special considerations
X Exceptions in event-driven code.
X SIGPIPE, EPIPE - might have more to do with long-lived processes rather than
  just event-driven programming, but still something to watch out for...
X You should almost always check the return code of your syscalls to see if they succeeded or not.

7. Promises:
X Future
X Future::AsyncAwait
X Future::Utils

8. Real-world uses for event-driven applications:
- Webhooks
- PubsubHubbub
- msg queue




Other topics:
X What is event-driven programming?
X Reactor: event loop that can receive multiple types of events and
  demultiplex them, delivering them to appropriate handlers.
- C10k problem
- EDA (event-driven architecture)
X Benefits of Event-driven
X How to debug event-driven code.

Traditional programs:
- CGI - web server calls your program, and your program does its thing and
  finishes.
X filters - grep, less, sed, etc. Like a function, the program takes its input
  and produces some output.

Perl features:
- first-class subroutines

- Can mix traditional architecture with event-driven (like docker that
  provides both an http and command-line interface.