1 hour dive into Erlang/OTP
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The document provides an overview of Erlang and its features for building scalable and fault-tolerant systems. It discusses how Erlang uses lightweight processes, message passing, and supervision to allow for high concurrency. It also covers how Erlang enables hot code upgrading and distribution across nodes.
![You should see:
Erlang R16B (erts-5.10.1) [source] [64-bit]
[smp:2:2] [async-threads:10] [hipe] [kernel-
poll:false] [dtrace]
Eshell V5.10.1 (abort with ^G)
1](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-71-320.jpg)
![[List]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-95-320.jpg)
![[1,2,3,4,5,6]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-96-320.jpg)
![1 MyList = [1,2,3,4].
[1,2,3,4]
2 [Head|Tail] = MyList.
[1,2,3,4]
3 Head.
1
4 Tail.
[2,3,4]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-99-320.jpg)
![1 MyList = [1,2,3,4].
[1,2,3,4]
2 [Head|Tail] = MyList.
[1,2,3,4]
3 Head.
1
4 Tail.
[2,3,4]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-100-320.jpg)
![1 MyList = [1,2,3,4].
[1,2,3,4]
2 [Head|Tail] = MyList.
[1,2,3,4]
3 Head.
1
4 Tail.
[2,3,4]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-101-320.jpg)
![1 MyList = [1, 2, 3, 4].
[1,2,3,4]
2 [X + 2 || X - MyList, X 2].
[5,6]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-103-320.jpg)
![[Strings]](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-104-320.jpg)
![1 MyString = Erlang is not Ruby.
Erlang is not Ruby
2 [Head2|Tail2] = MyString.
Erlang is not Ruby
3 Head2.
69 ASC](https://image.slidesharecdn.com/1hourdiveintoerlangotp-130322030112-phpapp02/85/1-hour-dive-into-Erlang-OTP-108-320.jpg)
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1 hour dive into Erlang/OTP
- 1. 1 hour dive into Erlang/OTP @jvalduvieco @jordillonch
- 5. 24x7x365
- 6. 24x7x365
- 7. Lots of critical concurrent transactions
- 8. Lots of critical concurrent transactions
- 9. Hardware or software breaks
- 10. Hardware or software breaks
- 11. Lots of code changes
- 12. Lots of code changes
- 13. Unscalable Unmaintainable } code
- 14. Unscalable Unmaintainable } code
- 15. Maintenance/Debug in production system
- 16. Maintenance/Debug in production system
- 17. Does it sound to you?
- 19. Simplicity...
- 20. Minimize defensive programming
- 23. t-shirt function size If
- 24. a
- 25. function
- 26. does
- 27. not
- 28. fit
- 29. on
- 30. your
- 31. t-shirt
- 32. it
- 33. is
- 34. too
- 35. long!
- 36. Single responsibility principle
- 37. No shared state between entities
- 38. High Concurrency
- 40. Light threads
- 41. Light threads hundreds of thousands of threads in one machine with a good cpu scheduler
- 42. Light threads hundreds of thousands of threads in one machine with a good cpu scheduler Lt Lt Lt
- 43. Message passing Lt Lt Lt
- 44. Message passing A shared nothing architecture that communicates through message passing Lt Lt Lt
- 45. Message passing A shared nothing architecture that communicates through message passing Lt Lt Lt
- 46. Process Mailbox Lt Lt Lt
- 47. Process Mailbox Every process has a mailbox with incoming messages, process take on convenience Lt Lt Lt
- 48. No shared state Lt S Lt S Lt S
- 49. No shared state Every process its own internal state stored in a variable avoiding lock contention Lt S Lt S Lt S
- 50. Soft realtime
- 51. Soft realtime You have no strict guarantees on latency but language is designed to have low latency
- 53. High availability High availability
- 54. Supervised processes Pa Pb
- 55. Supervised processes processes can be monitored by other processes, handling its termination Pa Pb
- 56. Fail early Pa Pb S
- 57. Fail early Fail as soon as possible and let someone handle bad data, someone will restart you Pa Pb S
- 58. Fail early Fail as soon as possible and let someone handle bad data, someone will restart you Pa Pb2 S
- 59. Hot code update Pb Pa v1 S Pc
- 60. Hot code update processes code and data can be replaced without loosing service Pb Pa v1 S Pc
- 61. Hot code update processes code and data can be replaced without loosing service Pb Pa v1 v2 S Pc
- 62. Distribution Node Node P P P P P P P P P P P P
- 63. Distribution Processes run on nodes and can be located wherever they are Node Node P P P P P P P P P P P P
- 64. How does it look like?
- 66. Show me the code!
- 67. Demo 1
- 68. Hands on
- 69. The shell
- 70. Type on your console: erl
- 71. You should see: Erlang R16B (erts-5.10.1) [source] [64-bit] [smp:2:2] [async-threads:10] [hipe] [kernel- poll:false] [dtrace] Eshell V5.10.1 (abort with ^G) 1
- 72. Variables
- 75. Can contain any type
- 76. You can do things like...
- 77. 1 Foo = 1. 1 2 Foo = 2. ** exception error: no match of right hand side value 2
- 78. Foo
- 79. is
- 80. bounded
- 81. to
- 82. 1 1 Foo = 1. 1 2 Foo = 2. ** exception error: no match of right hand side value 2
- 83. Foo
- 84. is
- 85. bounded
- 86. to
- 87. 1 1 Foo = 1. 1 Foo
- 88. ==
- 89. 2
- 90. ? 2 Foo = 2. ** exception error: no match of right hand side value 2
- 91. 1 Foo = 1. 1 2 Bar = 2. 2 3 Foo = Bar. ** exception error: no match of right hand side value 2
- 92. This is GREAT!
- 93. Now you have your basic error checking system implemented
- 94. Advanced types
- 95. [List]
- 96. [1,2,3,4,5,6]
- 97. You can do things like...
- 99. 1 MyList = [1,2,3,4]. [1,2,3,4] 2 [Head|Tail] = MyList. [1,2,3,4] 3 Head. 1 4 Tail. [2,3,4]
- 100. 1 MyList = [1,2,3,4]. [1,2,3,4] 2 [Head|Tail] = MyList. [1,2,3,4] 3 Head. 1 4 Tail. [2,3,4]
- 101. 1 MyList = [1,2,3,4]. [1,2,3,4] 2 [Head|Tail] = MyList. [1,2,3,4] 3 Head. 1 4 Tail. [2,3,4]
- 102. Do something to all or some items on a list (list comprehensions)
- 103. 1 MyList = [1, 2, 3, 4]. [1,2,3,4] 2 [X + 2 || X - MyList, X 2]. [5,6]
- 104. [Strings]
- 105. A list
- 106. You can do things like...
- 107. 1 MyString = Erlang is not Ruby. Erlang is not Ruby
- 108. 1 MyString = Erlang is not Ruby. Erlang is not Ruby 2 [Head2|Tail2] = MyString. Erlang is not Ruby 3 Head2. 69 ASC
- 109. =
- 110. “E” 4 Tail2. rlang is not Ruby
- 111. {Tuples}
- 112. {1,2,3}
- 113. Basic data container
- 114. random access
- 115. matcheable
- 116. You can do things like...
- 117. 1 Mytuple = {1,2,3,4}. {1,2,3,4} 2 A = 1. 1 3 B = 2. 2 4 {A,B,C,D} = {1,2,3,4}. {1,2,3,4} 5 C. 3 6 D. 4
- 118. 1 Mytuple = {1,2,3,4}. {1,2,3,4} 2 A = 1. 1 A
- 119. and
- 120. B
- 121. are 3 B = 2. bounded
- 122. variables 2 4 {A,B,C,D} = {1,2,3,4}. {1,2,3,4} 5 C. 3 6 D. 4
- 123. 1 Mytuple = {1,2,3,4}. {1,2,3,4} 2 A = 1. 1 A
- 124. and
- 125. B
- 126. are 3 B = 2. bounded
- 127. variables 2 4 {A,B,C,D} = {1,2,3,4}. {1,2,3,4} 5 C. pattern
- 128. matching 3 A==1? 6 D. B==2? 4
- 129. 1 Mytuple = {1,2,3,4}. {1,2,3,4} 2 A = 1. 1 A
- 130. and
- 131. B
- 132. are 3 B = 2. bounded
- 133. variables 2 4 {A,B,C,D} = {1,2,3,4}. C
- 134. and
- 135. D
- 136. are
- 137. {1,2,3,4} unbounded
- 138. 5 C. pattern
- 139. matching variables 3 A==1? 6 D. B==2? 4
- 140. functions
- 141. functions are types
- 142. single exit point
- 143. You can do things like...
- 144. foo_bar_func(Foo, Bar) - Result = Foo + Bar, Result.
- 145. This
- 146. is
- 147. a
- 148. arity
- 149. 2
- 150. function
- 152. parameters) foo_bar_func(Foo, Bar) - Result = Foo + Bar, Result.
- 153. This
- 154. is
- 155. a
- 156. arity
- 157. 2
- 158. function
- 160. parameters) foo_bar_func(Foo, Bar) - Result = Foo + Bar, Result. means
- 161. that
- 162. more
- 164. is
- 165. to
- 166. come
- 167. This
- 168. is
- 169. a
- 170. arity
- 171. 2
- 172. function
- 174. parameters) foo_bar_func(Foo, Bar) - Result = Foo + Bar, Result. means
- 175. that
- 176. more
- 178. is
- 179. to
- 180. come means
- 181. the
- 182. function
- 184. has
- 185. ended
- 186. This
- 187. is
- 188. a
- 189. arity
- 190. 2
- 191. function
- 193. parameters) foo_bar_func(Foo, Bar) - Result = Foo + Bar, Result. means
- 194. that
- 195. more
- 197. is
- 198. to
- 199. come Single
- 200. exit
- 201. point Returns
- 202. Result means
- 203. the
- 204. function
- 206. has
- 207. ended
- 208. 1 FooBar = fun(Foo, Bar) - 1 Foo + Bar 1 end. #Funerl_eval.12.82930912 2 Result = FooBar(1, 2). 3
- 209. atoms
- 210. A constant with name
- 211. lowercase
- 212. You can do things like...
- 213. 1 ok. ok 2 ko. ko 3 ok =:= ko. false 4 ok =:= ok. true
- 214. 1 MyFuncOK = fun() - {ok, 33} end. #Funerl_eval.20.82930912 2 MyFuncFail = fun() - {error, bad_arg} end. #Funerl_eval.20.82930912 3 {ok, Result} = MyFuncOK(). {ok,33} 4 {ok, Result2} = MyFuncFail(). ** exception error: no match of right hand side value {error,bad_arg}
- 215. atoms 1 MyFuncOK = fun() - {ok, 33} end. #Funerl_eval.20.82930912 2 MyFuncFail = fun() - {error, bad_arg} end. #Funerl_eval.20.82930912 3 {ok, Result} = MyFuncOK(). {ok,33} 4 {ok, Result2} = MyFuncFail(). ** exception error: no match of right hand side value {error,bad_arg}
- 216. atoms 1 MyFuncOK = fun() - {ok, 33} end. #Funerl_eval.20.82930912 2 MyFuncFail = fun() - {error, bad_arg} end. #Funerl_eval.20.82930912 } 3 {ok, Result} = MyFuncOK(). {ok,33} error 4 {ok, Result2} = MyFuncFail(). checking ** exception error: no match of right hand side value {error,bad_arg}
- 217. atoms 1 MyFuncOK = fun() - {ok, 33} end. #Funerl_eval.20.82930912 2 MyFuncFail = fun() - {error, bad_arg} end. #Funerl_eval.20.82930912 } 3 {ok, Result} = MyFuncOK(). {ok,33} error 4 {ok, Result2} = MyFuncFail(). checking ** exception error: no match of right hand side value {error,bad_arg} do
- 218. they
- 219. match?
- 220. modules
- 221. basic name spacing
- 223. You can do things like...
- 224. On your ${EDITOR} create cool_func.erl -module(cool_func). -export([foo_bar_func/2]). foo_bar_func (Foo, Bar) - Result = Foo + Bar, {ok, Result}.
- 225. On erlang shell type: 1 c(cool_module). {ok,cool_module} 2 {ok, Result3} = cool_module:sum(33, 44). {ok,77} 3 Result3. 77
- 226. Too easy? Let’s add some pattern matching on parameters!
- 227. area({square, Side}) - {ok,Side * Side}; area({circle, Radius}) - % almost :-) {ok, 3 * Radius * Radius}; area({triangle, A, B, C}) - S = (A + B + C)/2, {ok, math:sqrt(S*(S-A)*(S-B)*(S-C))}; area(Other) - {error, invalid_object}.
- 228. area({square, Side}) - {ok,Side * Side}; means
- 229. that
- 230. there
- 231. is
- 232. area({circle, Radius}) - another
- 233. matching
- 234. % almost :-) posibility {ok, 3 * Radius * Radius}; area({triangle, A, B, C}) - S = (A + B + C)/2, {ok, math:sqrt(S*(S-A)*(S-B)*(S-C))}; area(Other) - {error, invalid_object}.
- 235. area({square, Side}) - {ok,Side * Side}; means
- 236. that
- 237. there
- 238. is
- 239. area({circle, Radius}) - another
- 240. matching
- 241. % almost :-) posibility {ok, 3 * Radius * Radius}; area({triangle, A, B, C}) - S = (A + B + C)/2, {ok, math:sqrt(S*(S-A)*(S-B)*(S-C))}; area(Other) - {error, invalid_object}. mymodule:area({square, 10}). mymodule:area({circle, 10}). mymodule:area({triangle, 2, 2, 3.5}).
- 242. Want more? Let’s add some recursion!
- 243. Want more? Let’s add some recursion! Erlang does not use loops
- 244. factorial(0) - 1; factorial(N) - N * factorial(N-1).
- 245. OTP
- 246. Oh, This is Perfect!
- 247. OTP is a set of rock solid architecture patterns, practices and tools
- 248. Improves the design, fault tolerance and deployment of your app
- 249. Erlang is just a language, OTP makes it great for the real world
- 251. Basic architecture patterns
- 252. Supervisor S P P P S P P
- 253. Supervisor S P P P S P P
- 254. Supervisor spawns processes and handles its death
- 255. gen_server P P gs P
- 256. gen_server P P gs P
- 257. Generic single threaded server
- 258. gen_fsm P P gf{S} P
- 259. gen_fsm P P gf{S} P
- 260. Generic Finite State Machine
- 261. gen_event P P P em P P P
- 262. gen_event P P P em P P P
- 263. Event handler, you can subscribe to events
- 264. More on OTP... • File hierarchy • Applications • Releases • Basic abstraction libraries (logging, system...)
- 265. Let’s see a gen_server in action!
- 266. Introducing Simple Key Value Store
- 267. A server that is able to store {Key, Value} and retrieve them by Key
- 268. Demo II
- 269. skvs diagram S P gs ets
- 270. skvs diagram S P gs ets
- 271. Starting skvs Go to skvs source directory Compile ./rebar compile Start the Erlang node erl -pa ebin Start the app application:start(skvs).
- 272. Some commands Set a value skvs_server:set(“Key”,”Value”). skvs_server:set(“Key2”,”Value2”). Get a value skvs_server:get(“Key2”).
- 273. Code on client: skvs_server.erl start_link() - gen_server:start_link({local, skvs}, skvs_server, [], []). get(Key) - gen_server:call(skvs, {get, Key}). set(Key,Value) - gen_server:call(skvs, {set, Key, Value}). set_fire_and_forget(Key,Value) - gen_server:cast(skvs, {set, Key, Value}).
- 274. Code on client: skvs_server.erl start
- 275. gen_server start_link() - gen_server:start_link({local, skvs}, skvs_server, [], []). get(Key) - gen_server:call(skvs, {get, Key}). set(Key,Value) - gen_server:call(skvs, {set, Key, Value}). set_fire_and_forget(Key,Value) - gen_server:cast(skvs, {set, Key, Value}).
- 276. Code on client: skvs_server.erl start
- 277. gen_server start_link() - gen_server:start_link({local, skvs}, skvs_server, [], []). get(Key) - gen_server:call(skvs, {get, Key}). sync
- 278. call
- 279. to
- 280. server set(Key,Value) - (waits
- 281. for
- 282. reply) gen_server:call(skvs, {set, Key, Value}). set_fire_and_forget(Key,Value) - gen_server:cast(skvs, {set, Key, Value}).
- 283. Code on client: skvs_server.erl start
- 284. gen_server start_link() - gen_server:start_link({local, skvs}, skvs_server, [], []). get(Key) - gen_server:call(skvs, {get, Key}). sync
- 285. call
- 286. to
- 287. server set(Key,Value) - (waits
- 288. for
- 289. reply) gen_server:call(skvs, {set, Key, Value}). set_fire_and_forget(Key,Value) - gen_server:cast(skvs, {set, Key, Value}). async
- 290. call
- 291. to
- 292. server (fire
- 294. forget)
- 295. Callback code: skvs_server.erl %% Client Callbacks on server %% Sync calls, expects response handle_call({set, Key, Value}, _From,State) - {reply, set_value(Key,Value), State}; handle_call({get, Key}, _From, State) - {reply, get_value(Key), State}. %% Async calls, do not expect response handle_cast({set, Key, Value}, State) - set_value(Key,Value), {noreply, State}.
- 296. Callback code: skvs_server.erl %% Client Callbacks on server %% Sync calls, expects response handle_call({set, Key, Value}, _From,State) - {reply, set_value(Key,Value), State}; handle_call({get, Key}, _From, State) - {reply, get_value(Key), State}. %% Async calls, do not expect response handle_cast({set, Key, Value}, State) - set_value(Key,Value), {noreply, State}. return
- 297. value
- 298. Callback code: skvs_server.erl %% Client Callbacks on server %% Sync calls, expects response handle_call({set, Key, Value}, _From,State) - {reply, set_value(Key,Value), State}; handle_call({get, Key}, _From, State) - {reply, get_value(Key), State}. %% Async calls, do not expect response handle_cast({set, Key, Value}, State) - set_value(Key,Value), {noreply, State}. Survives
- 299. between
- 301. value requests
- 302. Actual work...: skvs_server.erl %% Private functions set_value(Key, Value) - % Insert Key, Value into ETS. % Fail early {ok,Result}=case ets:insert(data_store,{Key,Value}) of true - {ok, {Key,Value}}; {error, Reason} - {error, Reason} end, Result.
- 303. Actual work...: skvs_server.erl %% Private functions set_value(Key, Value) - % Insert Key, Value into ETS. % Fail early {ok,Result}=case ets:insert(data_store,{Key,Value}) of true - {ok, {Key,Value}}; {error, Reason} - {error, Reason} end, ETS
- 304. is
- 305. a
- 306. Key
- 307. value
- 308. store
- 310. RAM
- 311. Use cases
- 312. Gaming Industry
- 313. Gaming Industry
- 314. Messaging / IM
- 315. Messaging / IM
- 316. Payments
- 317. Payments
- 318. Databases
- 319. Databases
- 320. Others
- 321. Others
- 322. Some day...
- 323. Every highly interactive website? ;)
- 324. Pay Hello Ouch! Every highly interactive website? ;) Would you... Hey NO! ! Hi Buf
- 325. Internet of things
- 326. And now what?
- 328. Use a great IDE • IntelliJ + Erlang (plugin) • Sublime Text + SublimErl • Emacs
- 329. Read some books
- 331. Join mailing lists • Official Erlang mailing list • http://erlang.org/mailman/listinfo/erlang- questions • Join Barcelona Erlang user group on google groups
- 332. Find know-how • Check http://www.erlang-factory.com/ videos • Search for Erlang conferences on slideshare • Pray for an http://erlangcamp.com/ near your city
- 333. Read some code
- 334. This is the result of 6 months of fun learning Erlang/OTP
- 335. We are looking for awesome projects http://es.linkedin.com/in/jvalduvieco http://es.linkedin.com/in/jllonch
- 337. Thank you! https://github.com/jvalduvieco/betabeers_201303 we
- 338. hope
- 339. you
- 340. feel
- 342. him
- 343. :) (we
- 344. did)