Thinking in Erlang

One day Erlang training.

Goals

This training should get you started with Erlang and understand how to design a highly available distributed system. Because there is only one day, we focus on the essential concepts and skip over many details that would be covered in the normal three days course.

After learning the basics and doing a few exercises we will start writing a simple chat client and server and improve it as we learn new things.

You are encouraged to help the people around you once you figure things out for yourself.

At the end of this training you should be able to:

Install Erlang
Have basic knowledge of the Erlang language
Understand concurrency and message passing
Learn how to handle errors
Understand how to build highly available systems
Recognize Joe Armstrong, Robert Virding and Mike Williams

Requirements

Your own laptop
Erlang R16B02:
Wi-Fi connection for installing Erlang during the training
Otherwise, read below if you wish to install Erlang beforehand

Programme

Erlang Installation

20 minutes, Wi-Fi required

If you can, please come with Erlang R16B02 already installed on your machine. Please use the ESL packages. Arch Linux users can use the pacman package directly.

If everyone comes with Erlang installed we can move through this part quicker.

Install Erlang
Watch Erlang the Movie while it downloads/installs
Start and stop the shell (Ctrl+C and Ctrl+G)
io:format("Hello world!")

Overview of an Erlang system

20 minutes

Get a first look at modules, applications, processes and supervision trees.

erlang:loaded()
application:loaded_applications()
i()
observer:start()
Diagram summarizing a distributed Erlang system

Basic syntax and types

60 minutes

We will cover the following types which are necessary to follow the training, and skip the few types we won't need.

integer
atom
list
tuple
pid
reference
fun

We will cover the following syntax.

Module
Function definition
Function clauses
Guards
Pattern matching in function clauses
Exports
Local function calls
Remote function calls
Case .. of
Pattern matching with =

Recursion

40 minutes

We will cover the following recursion concepts:

Recursing through a list
Accumulator
Map
Program loop

Concurrency and message passing

120 minutes

What makes Erlang so special.

Overview of processes
Spawn
Order of execution is undefined
Processes are cheap
Processes are isolated
Message passing
Receive
Receive .. after
Selective receive
Server processes
RPC
Process registry

Remote error handling

60 minutes

First taste of high availability.

Monitors
Safe RPC
Links
What to do when processes crash?
Supervisor
Supervision trees

Quick look at distribution

30 minutes

Connect nodes, make them speak together.

Nodes
Node names
Connecting nodes
Global process registry

Highly available systems