A short presentation about Erlang, specifically designed for concurrency characteristics. For the course: Scientific Writing and Communication (KTH Royal Institute of Technology)

1. Erlang
in 10 minutes
Maria Stylianou
November 19th, 2012
Scientific Writing and Communication

2. Outline
● What is Erlang
● What Erlang offers
● Concurrent Programming
● Four things to remember!
2

3. What is Erlang (1/4)
"The world is concurrent.
Things in the world don't share data.
Things communicate with messages.
Things fail. "
- Joe Armstrong
3

4. What is Erlang (2/4)
● Type: Programming Language
● Date of Birth: ~1986
● Place of Birth: Ericsson, Sweden
● Father: Joe Armstrong
● Aim of Existence:
Target robust apps
in telecom world
4

5. What is Erlang (3/4)
● Functional Programming Language i++
● OS Independent
● Actor Model
?
spawn
A1:6
A1:5 A2:1
5

6. What is Erlang (3/4)
● Functional Programming Language i++
● OS Independent
● Actor Model
?
spawn
A1:6
A1:5 A2:1
msg
msg
msg
msg
5

7. What is Erlang (4/4)
● Build real-time systems
○ scalable
○ highly available
○ reliable
● Built-in support for
○ concurrency
○ distribution
○ fault tolerance
6

8. What Erlang offers
Among many others...
● Sequential Programming
● Concurrent Programming
7

9. Concurrent Programming
● Process Creation
● Process Communication
● Timeouts
● Fault Tolerance
8

10. Concurrent Process
Programming Creation
Light weight processes
-module(say). % say.erl
-export([start/0, say_something/2]).
say_something(What, 0) -> Pattern Matching
done;
say_something(What, Times) -> if-then-else
io:format("~p~n", [What]),
say_something(What, Times - 1).
start() ->
spawn(say, say_something, [emdc, 3]), Create 2
spawn(say, say_something, [rocks, 3]). processes
9

11. Concurrent Process
Programming Creation
Light weight processes
-module(say). % say.erl
-export([start/0, say_something/2]).
say_something(What, 0) -> Pattern Matching
done;
say_something(What, Times) -> if-then-else
io:format("~p~n", [What]),
say_something(What, Times - 1).
start() ->
spawn(say, say_something, [emdc, 3]), Create 2
spawn(say, say_something, [rocks, 3]). processes
9

12. Concurrent Process
Programming Communication
Asynchronous Message Passing
"Send and Pray"
A B
B! {msg, [1,2]} receive
{msg, List} ->
handle(List)
end.
10

13. Concurrent
Programming Timeouts
To avoid locking processes
A B
B! {msg, [1,2]} receive
{msg, List} ->
handle(List)
after 1000 ->
handle_timeout()
end.
11

14. Concurrent Fault
Programming Tolerance
● Exits
● Exit signals
A B link(A)
link
● Trapping Exits
A B
process_flag(trap_exit, true)
12

15. Four Things to remember!
Erlang's Most Valuable Characteristics
1 Concurrency
2 Scalability
3 High Performance
4 Fault Tolerance
13

16. http://learnyousomeerlang.com 14

17. References
1. Erlang/OTP, http://www.erlang.se
2. Erlang programming language, http://www.erlang.org
3. Learn you some Erlang, http://learnyousomeerlang.com
4. Joe Armstrong, "Programming Erlang, Software for a
Concurrent World"
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18. Erlang
in 10 minutes
Maria Stylianou
November 19th, 2012
Scientific Writing and Communication