why erlang

ERLANGSILICON VALLEY

MEETUP

April 14, 2014

AGENDA6:30 - Doors open

6:45 - Introduction / Announcements

7:00 - Why Erlang?

7:45 - Meetup Organization

8:15 - Erlang Intro

9:00 - Doors close

INTRODUCTION AND

ANNOUNCEMENTS

DOUG GOLDIE

Freelance developer, architect, consultant

Ruby, Rails stack

Boatbound, V.me at Visa, Paynearme

doug@codecauldron.com

WHY ERLANG?by Doug Goldie

WHATSAPP

• 465M monthly users

• 19B messages in & 40B out per day

• Small team (~10 on Erlang), handle development and ops

• ~ 550 servers + standby gear

• > 11,000 cores

A YEAR AGO…• I took the summer off….

•“Why Erlang?”

•Challenges of SOA

•Curious about Erlang.

•Learn a functional language again.

ERICSSON

TELECOM NEEDED• Concurrency• Distribution• Fault Tolerance• Soft real-time• Hot code upgrade• Incremental code loading• External interfaces

ERLANG

CONCURRENCY

• Isolated processes

•Asynchronous messaging passing

•Actor model

Distributed

FAULT TOLERANCE

Reliability

Redundancy

Nine nines 99.9999999%

SOFT REAL-TIME

Deadlines

Soft allows some slip

SOFT REAL-TIME

Lightweight processes.

Garbage collection

HOT CODE UPGRADE

INCREMENTAL CODE LOADING

EXTERNAL INTERFACES

–Robert Virding, OTP class, 2014

“It’s about building Systems.”

ERLANG LANGUAGE

FUNCTIONAL

fac(N) when N == 0 -> 1;fac(N) when N > 0 -> N*fac(N-1).

Recursion

double([H|T]) -> [2*H|double(T)]; double([]) -> [].

Pattern matching

MODULES, ETC.

• Modules

• Behaviours

ERLANG/OTP

OTP•Library of Design Patterns

•Supervision Tree

•Workers and supervisors

•Behaviours

CLIENT SERVER

gen_server

FINITE STATE MACHINE

gen_fsm

ELIXIR

• Jose Valim

• Light layer of syntactic sugar

• Pipes

• Macros

THE WEB

THE WEB

• Concurrent

• Soft real-time

• Asynchronous

• Omnipresent

• Internet of Things

REFERENCES• Erlang and the Web

http://ninenines.eu/docs/en/cowboy/HEAD/guide/erlang_web/

• Concurrency Oriented Programming in Erlanghttp://www.guug.de/veranstaltungen/ffg2003/papers/ffg2003-armstrong.pdf

• Why OO Suckshttp://www.sics.se/~joe/bluetail/vol1/v1_oo.html

• Erlang Centralhttps://erlangcentral.org/

• Erlang Historyhttp://www.erlang.org/faq/academic.html

• WhatsApp presentationhttp://www.erlang-factory.com/conference/show/conference-6/home/#rick-reed

DOUG GOLDIEdoug@codecauldron.com