MythBashers: An Adventure in Overlooked Technologies - Avdi Grimm

Transcript

1. MYTHBASHERS AVDI GRIMM 0
3. JAMIE HYNEMAN
4. TAKE A COMMON MYTH
5. DEVISE AN EXPERIMENT
6. BUILD A TEST RIG
7. TEST THE MYTH!
8. MAKE A DETERMINATION Confirmed Plausible Busted
9. COOL TOYS
10. ME TOO!
11. RUBY
12. LANGUAGES JavaScript Python Perl Java/C# Clojure/Erlang/Haskell/Scala PHP COBOL?
13. LINGUA FRANCA
14. SHELL!
15. BASH
16. THE MYTH "Bash isn't Webscale"
17. THE BUILD A single-page web chat application, backed by a Bash script
18. https://github.com/avdi/walrus
19. HIGHLIGHTS
20. SERVING HTTP
21. NETCAT Like cat(1) for TCP/UDP sockets.
22. A SIMPLE HTTP SERVER $ p r i n t f " H T T P / 1 . 1 2 0 0 O K \ r \ n \ r \ n H e l l o w o r l d \ n " | n c - l 8 0 8 0
23. CLIENT $ c u r l l o c a l h o s t : 8 0 8 0 H e l l o w o r l d
24. NETCAT OUTPUT $ p r i n t f " H T T P / 1 . 1 2 0 0 O K \ r \ n \ r \ n H e l l o w o r l d \ n " | n c - l 8 0 8 0 G E T / H T T P / 1 . 1 U s e r - A g e n t : c u r l / 7 . 3 2 . 0 H o s t : l o c a l h o s t : 8 0 8 0 A c c e p t : * / *
25. SERVING PAGES DYNAMICALLY
26. NETCAT IS READ/WRITE No callbacks.
27. DYNAMIC NETCAT Branching on input.
28. COPROCESSES
29. c o p r o c N A M E C O M M A N D
30. ROT13 COPROCESS $ c o p r o c r o t 1 3 { s t d b u f - o L t r ' [ A - Z a - z ] ' ' [ N - Z A - M n - z a - m ] ' ; [ 1 ] 2 6 8 1 2
31. COPROCESS FILEHANDLES $ e c h o $ { r o t 1 3 [ 0 ] } 6 3 $ e c h o $ { r o t 1 3 [ 1 ] } 6 0
32. WRITING AND READING $ e c h o " h e l l o , w o r l d " > & $ { r o t 1 3 [ 1 ] } $ e c h o " t h i s i s a s e c r e t " > & $ { r o t 1 3 [ 1 ] } $ r e a d l i n e < & $ { r o t 1 3 [ 0 ] } $ e c h o $ l i n e u r y y b , j b e y q $ r e a d l i n e < & $ { r o t 1 3 [ 0 ] } $ e c h o $ l i n e g u v f v f n f r p e r g
33. ENDING A COPROCESS THE RUDE WAY $ k i l l $ { r o t 1 3 _ P I D }
34. ENDING A COPROCESS THE POLITE WAY Closing a filehandle s o m e c o m m a n d 1 & > - Closing a filehandle without a command e x e c 6 0 & > -
35. Interpolating the coprocess STDIN e x e c $ { r o t 1 3 [ 1 ] } & > - (Doesn't parse correctly)
36. Using e v a l e v a l " e x e c $ { r o t 1 3 [ 1 ] } & > - " Simple, right?
37. IÄ! IÄ! CTHULHU FHTAGN! Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
38. NETCAT AS A COPROCESS # S t a r t n e t c a t c o p r o c n c ( n c - l 8 0 8 0 ) # P l u g i t i n t o a r e q u e s t h a n d l e r h a n d l e _ r e q u e s t $ { n c _ P I D } < & $ { n c [ 0 ] } > & $ { n c [ 1 ] } # C l o s e f i l e h a n d l e s e v a l " e x e c $ { n c [ 1 ] } > & - " e v a l " e x e c $ { n c [ 0 ] } < & - "
39. ORGANIZING THE PROGRAM
40. SHELL FUNCTIONS
41. MINIATURE SHELL SCRIPTS Positional params ($ 1 , $ 2 , $ * , etc.) Redirectable STDIN, STDOUT, and STDERR Return an integer exit status
42. NAIVE ROT13 FUNCTION r o t 1 3 ( ) { e c h o " $ 1 " | s t d b u f - o L t r ' [ A - Z a - z ] ' ' [ N - Z A - M n - z a - m ] ' } $ r o t 1 3 " p s s s t " c f f f g
43. PIPELINE ROT13 FUNCTION r o t 1 3 ( ) { s t d b u f - o L t r ' [ A - Z a - z ] ' ' [ N - Z A - M n - z a - m ] ' } $ e c h o " p s s s t " | r o t 1 3 c f f f g
44. LOCAL VARIABLES f o o ( ) { b a r = 4 2 # g l o b a l ! } $ f o o $ e c h o $ { b a r } 4 2 f o o ( ) { l o c a l b a r = 4 2 # l o c a l } $ f o o $ e c h o $ { b a r } # n o o u t p u t
45. DECLARING LOCALS BEFORE ASSIGNMENT g r e e t ( ) { l o c a l n a m e r e a d n a m e e c h o " H e l l o , $ n a m e " }
46. SERVING STATIC FILES H T T P / 1 . 1 G E T / i n d e x . h t m l
47. CONTENT TYPE t e x t / h t m l , a p p l i c a t i o n / j s o n , etc.
48. ASSOCIATIVE ARRAYS (AKA Map, Dictionary, Hash) d e c l a r e - A c o n t e n t _ t y p e s = ( [ j s ] = t e x t / j a v a s c r i p t [ h t m l ] = t e x t / h t m l )
49. FIND CONTENT TYPE FOR EXTENSION $ e c h o $ { c o n t e n t _ t y p e s [ h t m l ] } t e x t / h t m l With default: $ e c h o $ { c o n t e n t _ t y p e s [ f o o ] - t e x t / p l a i n } t e x t / p l a i n
50. GET FILE EXTENSION $ f i l e = p u b l i c / i n d e x . h t m l $ e c h o $ { f i l e # # * . } h t m l
51. SERVING A FILE l o c a l f i l e = " p u b l i c / $ { p a t h } " i f [ - f " $ { f i l e } " ] ; d o l o c a l e x t = " $ { f i l e # # * . } " l o c a l t y p e = " $ { c o n t e n t _ t y p e s [ $ { e x t } ] } " p r i n t f " H T T P / 1 . 1 2 0 0 O K \ r \ n " p r i n t f " C o n t e n t - T y p e : $ { t y p e } \ r \ n \ r \ n " c a t " $ { f i l e } " f i
52. ACTOR MODEL 1. Asynchronous process 2. Queue for communication
53. But this is Bash...
55. JOHN AGAR B-List Actor
58. B‑MOVIE ACTOR MODEL 1. Asynchronous process: a subshell 2. Queue for communication: a named pipe (FIFO)
59. CREATE AN ACTOR a g a r ( ) { # . . . }
60. GET ACTOR NAME AND ARGS l o c a l n a m e = $ 1 l o c a l a r g s = $ { @ : 1 }
61. CREATE PIPE m k d i r - p f i f o s l o c a l f i f o n a m e = f i f o s / $ { n a m e } m k f i f o $ { f i f o n a m e }
62. SPAWN ACTOR { q u e u e = $ { f i f o n a m e } $ { n a m e } $ { a r g s [ @ ] } r m - f $ { f i f o n a m e } } &
63. "SEND" HELPER s e n d ( ) { l o c a l d e s t = $ 1 l o c a l m e s s a g e = $ { * : 1 } e c h o " $ { m e s s a g e } " > f i f o s / $ { d e s t } & }
64. CREATE AN ACTOR a g a r m a i n
65. "MAIN" FUNCTION m a i n ( ) { w h i l e t r u e ; d o s e r v e _ w i t h _ c o p r o c & r e a d < $ { q u e u e } d o n e }
66. SIGNALING MAIN # . . . r e a d r e q _ l i n e s e n d m a i n " c o n t i n u e " # . . .
67. TAKE THAT, ERLANG!
68. REALTIME UPDATES
69. SERVER‑SENT EVENTS (SSE) W3C Standards Track Supported: Firefox/Chrome/Safari/Opera
70. CLIENT SIDE v a r s o u r c e = n e w E v e n t S o u r c e ( ' / u p d a t e s ' ) ; s o u r c e . o n m e s s a g e = f u n c t i o n ( e v e n t ) { a l e r t ( e v e n t . d a t a ) ; } ;
71. SERVER SIDE H T T P / 1 . 1 2 0 0 O K C o n t e n t - T y p e : t e x t / e v e n t - s t r e a m d a t a : T h i s i s m e s s a g e 1 d a t a : T h i s i s m e s s a g e 2 . . .
72. Hooray for plain text!
73. w h i l e r e a d d a t a < f i f o / u p d a t e s ; d o p r i n t f " d a t a : $ { d a t a } \ n \ n " d o n e
74. THE MYTH "Bash isn't Webscale"
75. I got it working... barely.
76. ANALYSIS Slow Unreliable Only works in Firefox (?!) Leaks Processes FIFOs are a pain to work with So is netcat
77. This was a terrible idea!
78. MYTH: CONFIRMED
79. EXPERIMENTATION, NOT DEMONSTRATION
80. When we experiment—when we try things, and we fail—we start to ask why, and that’s when we learn. –Jamie Hyneman
81. A story to tell
82. Abstractions stripped away SQL HTTP
83. Greater familiarity with tools Netcat psql
84. Increased comfort with Bash scripting
85. It was fun
86. EXPERIMENT!
87. THANK YOU! Code: https://github.com/avdi/walrus I make screencasts: RubyTapas.com @avdi / avdi@avdi.org
88. MythBusters: © 2014 Discovery Communications, LLC. Photo of Tom Cruise by Gareth Cattermole © 2010 Getty Images "The Mole People" poster © Universal Pictures All others either unknown or in the public domain