Short OCRuby talk for Rubyists on how Crystal came in very handy

1. CRYSTAL IS A RUBYISTS FRIEND
(QUICK ANECDOTE)
FORREST CHANG (OCRUBY)
FKCHANG2000@YAHOO.COM

2. BEFORE WE START
Which of the following caode samples is Ruby?

3. APPLICATION 1
class App < Roda
plugin :streaming
plugin :basic_auth, authenticator: proc {|user, pass| [user, pass] == %w[client password]}
route do |r|
r.basic_auth {
stream do |out|
puts "streaming"
IO.popen("tail -f #{SYSTEM_LOG}") do |io|
io.each { |s|
out << s
}
end
end
}
end
end
run App.freeze.app

4. APPLICATION 2
ws "/ws" do |socket|
socket.on_message { |message|
puts "Streaming #{SYSTEM_LOG}"
if message == "TopSecret1234!"
Process.run("tail", {"-f", SYSTEM_LOG} ) { |proc |
proc.output.each_line { |line|
socket.send line
}
}
end
}
end
Kemal.run

5. HARD TO TELL WHICH IS RUBY?
That's the point
The 2nd one is Crystal
Easy/Comfortable for Rubyists
A subset compiles for both language

6. BACKGROUND
Wanted to stream syslog entries real time for visualization in browser
based app
Host machine, old, small - want a corresponding lightweight solution
Wanted to try Roda
Combined need (bullet 1) and desire (bullet 3)

7. RODA
Small and light
Uses a routing tree for routes (key distinguisher)
Faster than Sinatra 15042.26 rps vs 4441.61 rps
Reasons Why
http://roda.jeremyevans.net/index.html
https://github.com/luislavena/bench-micro#requestssec
http://roda.jeremyevans.net/why.html

8. RODA EXPERIENCE
Fairly easy to use (though routing tree is different)
Supported streaming output pretty easily
Maybe an hour plus to get running

9. PROBLEM
Browser supports streaming output
Javascript does not - D'oh!
Need Server Side Events or Websockets for same effect
Darn! Back to the drawing board

10. RODA WEBSOCKET SUPPORT
Built in plugin (Roda designed for and heavily uses plugins) - Yay!
Requires faye, Event Machine, mutexes – Hmm.
Quick and small solution getting more complex and larger
http://roda.jeremyevans.net/rdoc/classes/Roda/RodaPlugins/Websockets.htm

11. SO HOW ABOUT CRYSTAL?
Want a framework vs writing raw calls
Enter Kemal - "sinatra for Crystal"
Crystal about as fast and as small as Golang
But is a "statically typed, type inferenced Ruby that compiles to native
code"
So all the bene ts of Golang, with the Joy of Ruby
http://kemalcr.com/

12. KEMAL SPEED
44X faster that Sinatra
Framework Request Per Second Avg. Response Time
Kemal (Production) 100238 0.395ms
Sinatra (Thin) 2274 43.82ms

13. KEMAL WEBSOCKETS SUPPORT
Built in
Fast
Thor is used to run the benchmark.
thor -A 10000
Crystal (Kemal) CPU 1.85 Memory 11.2 MB
Node.js (ws) CPU 38.95 Memory 906.3 MB
This benchmark was performed on a 2013 Late Macbook
Pro with 2Ghz i7 and 8G ram.
P.S: Less is better
http://localhost:3000/

14. One of the prime reasons people left Ruby for node was real time push (i.e.
websockets), or performance/resources
This shows Crystal exceeds node in all 3 of those, w/the joy of Ruby

15. KEMAL EXPERIENCE
took about 15 min to get it working
Kemal author @sdogruyol super responsive/helpful on gitter
Since added functionality to that initial code
Success! Got the job done, on to the app
https://gitter.im/crystal-lang/crystal

16. SUMMARY
Crystal easy/comfortable for Rubyists
Fast and small
Kemal instead of sinatra, roda, cuba, etc.
For Rubyists, Crystal can be better t than Golang esp. if starting from
scratch
Community/Gitter active and helpful
Be Happy and Productive