Elixir at Work

Erick Camacho @ecamacho

November 2016

ex - Nubleer (a mexican startup)

What we did

1. Support for ebooks
2. Support for a new payment gateway (Stripe)
3. A recommendation system (recommends magazines, comics, ebooks, videos and news)

A bit of background

We were using Go

Great performance an a small memory footprint

But the language...

It isn't dynamic

It's hard to model complex objects hierarchies

Fault tolerance has to be managed by hand

1 year later it has been a success

This is what I learned

1. Embrace OTP

OTP apps encapsulate common functionality

and group processes together

Each OTP app should have a Supervisor

mix new recommendations --module Recommendations --sup
mix new payments --module Payments --sup
					

					#In your phoenix app
defp deps do
    [{:phoenix, "~> 1.2.1"},
     ...
     {:payments, 
     git: "git@yourgitserver.com:nubleer/payments.git", 
     checkout: "0.0.1"},
     {:recommendations, 
     git: "git@yourgitserver.com:nubleer/payments.git", 
     checkout: "0.0.1"},
   ]
end
					

					#In your phoenix app
def application do
    [mod: {Services, []},
     applications: [:phoenix, ...,
     :payments, :recommendations]]
end
					

2. Use Umbrella projects

							mix new nubleer --umbrella 
						

							#inside apps folder
mix phoenix.new services
mix new recommendations --module Recommendations --sup
mix new payments --module Payments --sup
						

In your phoenix app

						defp deps do
    [{:phoenix, "~> 1.2.1"},
     ...
     {:payments, in_umbrella: true},
     {:recommendations, in_umbrella: true},
   ]
end
					

No need to update mix dependencies

All on the same repo

reload() works!

3.

Supervisor strategies

One for one

Global GenServer

Example: A gen server that calculates the trending magazines for each day

Simple one for one

Creates a Gen Server each time a request is made

One process per user

Example: We create a GenServer each time a user requests her personalized recommended ebooks

Poolboy

Creates a pool of GenServers and load balance messages among them

Example: We create a set of RabbitMQ listeners per each RabbitMQ exchange

And more...

Plugs are awesome

Ecto rocks

Invest on training

With Elixir...

Q & A

Erick Camacho @ecamacho

https://ecamacho.github.io/elixir_at_work