A Sip of Elixir

An internal talk I gave at work to present the Elixir language and the Phoenix Framework to my colleagues.

Transcript

1. October 2020 - 1 A SIP OF ELIXIR @simonedavico
2. October 2020 - 2 WHY AM I HERE? I have too many vacation days 2 October 2020 -
3. October 2020 - 3 WHY AM I HERE? I have too many vacation days 3 October 2020 - I am waiting for my colleague Nicola to come back from lunch
4. October 2020 - 4 MY VACATIONS IN NUMBERS • ~2 weeks • 1 book Programming Phoenix • 1 video course The Pragmatic Studio LiveView course • 1 small app, many mini apps Rumbl
5. October 2020 - 5 PROGRAM FOR TODAY • Erlang What it is and why it matters Who is using it, and how • Elixir Why it is better than plain Erlang A tour of syntax • Phoenix Framework High level presentation Demo: rumbl • Bonus: Phoenix LiveView
6. October 2020 - 6 IN THE BEGINNING THERE WAS ERLANG Erlang was created at Ericsson in 1986. • The erlang is a unit of traffic density in a telecommunications system. • Erlang also stands for Ericsson Language
7. October 2020 - 7 ERLANG RUNTIME SYSTEM DESIGN • Distributed Out of the box • Fault tolerant Let it crash • Massively scalable Actor model • Massively concurrent Lightweight processes
8. October 2020 - 8 BATTERIES INCLUDED (1) • ETS Key/Value in memory store • Mnesia Distributed database based on ETS The Erlang OS distribution includes OTP, a set of libraries to build highly concurrent and distributed systems
9. October 2020 - 9 BATTERIES INCLUDED (2) • Dialyzer Static code analysis tool “Discrepancy analyze for Erlang” • Observer System monitoring and inspection • …
10. October 2020 - 10 STUFF IMPLEMENTED WITH ERLANG (1) • League of Legends Chat servers • Call of Duty Multiplayer infrastructure • WhatsApp 900M users infra managed by 50 engineers 2 million connections on a single node
11. October 2020 - 11 STUFF IMPLEMENTED WITH ERLANG (2) • Discord 5M users with Erlang, 11M with Erlang + Rust • Heroku Router of their PaaS, plus other pieces • AXD-301 0.6 seconds of downtime in 20 years (!) Continuous Deployment with scp (!!!)
12. October 2020 - 12 WHY THE DETOUR? 12 October 2020 -
13. October 2020 - 13 STANDING ON THE SHOULDERS OF GIANTS (1) Elixir: runs on the same runtime • Builds on top of Erlang OTP • Provides some abstractions to handle concurrency: GenServer, GenStages, Agents • Modern language features: mix, ExUnit, Hex Docs, macros (!), progressive typing, formatter…
14. October 2020 - 14 LET’S HACK A look at Elixir syntax 14 October 2020 -
15. October 2020 - 15 STANDING ON THE SHOULDERS OF GIANTS (RESUMED) Elixir: runs on the same runtime • Builds on top of Erlang OTP • Provides some abstractions to handle concurrency: Tasks, GenServers, GenStages, Agents • Modern language features: mix, ExUnit, Hex Docs, macros (!), progressive typing, formatter…
16. October 2020 - 16 ACTOR MODEL IN ELIXIR Processes • think infinite loops • are independent • are location transparent • exchange messages • keep internal state Elixir is multiparadigm: this is OOP as envisioned by Alan Kay!
17. October 2020 - 17 STANDING ON THE SHOULDERS OF GIANTS (2) • Borrows from different communities • Nice tooling for building web applications • Nice tooling for building IoT applications Phoenix Framework Nerves IoT Platform
18. October 2020 - 18 STANDING ON THE SHOULDERS OF GIANTS (2) • Borrows from different communities • Nice tooling for building web applications • Nice tooling for building IoT applications Phoenix Framework Nerves IoT Platform
19. October 2020 - 19 THE PHOENIX FRAMEWORK • MVC • Both APIs and server rendered templates • Real time client server communication • Code generators • LiveDashboard • Convention over configuration
20. October 2020 - 20 HTTP LAYER Plug: a specification for composable modules for connection management • Front and center of Phoenix HTTP layer • Functional approach to request handling: @spec create(Plug.Conn.t(), map) :: Plug.Conn.t()
21. October 2020 - 21 DATA LAYER Ecto: data validation, persistence and querying • Changesets: data validation • Schemas: ORM mapping • Query: composable DSL for SQL Migrations, Data Seeding • Sandbox: run integration tests agains the DB without worrying about data integrity
22. October 2020 - 22 VIEW LAYER Phoenix Views: Phoenix templating system • Html with embeddable Elixir expressions • Utilities for binding forms to changesets • Can render anything, not only html
23. October 2020 - 23 REAL-TIME UTILITIES • PubSub: built in publish-subscribe mechanism • Channels: real time client-server communication • Presence: user presence tracking • LiveView: build real-time apps with only server side code GenServer PubSub Channels Presence LiveView
24. October 2020 - 24 LET’S HACK Let’s create a small web application 24 October 2020 -
25. October 2020 - 25 LEARNING RESOURCES • Programming Elixir • Programming Phoenix • Real Time Phoenix • Pragmatic Studio - Phoenix LiveView course • Elixir School • r/elixir reddit • Elixir forum • GOTO Conf 2019 - The Soul of Erlang and Elixir