The document presents an overview of distributed programming using Ruby, highlighting Remote Method Invocation (RMI) also known as DRuby. It demonstrates how to authenticate users through a simple service setup, showcasing the ease of implementation and the potential risks associated with running unsafe code. The author, Mark Bates, who is a long-time Rubyist, shares insights and practical examples of utilizing DRuby and Rinda for interprocess communication.

1. A Tour of Distributed
Programming with Ruby
with Mark Bates

2. Mark Bates

3. Mark Bates
Rubyist since 2005

4. Mark Bates
Rubyist since 2005
Freelance Consultant

5. Mark Bates
Rubyist since 2005
Freelance Consultant
Musician

6. Mark Bates
Rubyist since 2005
Freelance Consultant
Musician
Author

7. Distributed
Programming
with Ruby
Addison-Wesley (2010)
http://books.markbates.com

8. Programming
in CoffeeScript
Addison-Wesley (2012)
http://books.markbates.com

9. WHO? WHAT? WHEN? WHY?
NOT SO MUCH HOW

10. No HOW?
What’s the point?

11. RMI - REMOTE METHOD INVOCATION
KNOWN ALIASES: DRB, DRUBY, DISTRIBUTED RUBY

12. What?

13. What?
Call methods remotely

14. What?
Call methods remotely
Standard Library, no additional packages

15. What?
Call methods remotely
Standard Library, no additional packages
Easy and Powerful

16. What?
Call methods remotely
Standard Library, no additional packages
Easy and Powerful
EXTREMELY DANGEROUS!!

17. When/Why?

18. When/Why?
Fast and Easy

19. When/Why?
Fast and Easy
Built into standard library

20. When/Why?
Fast and Easy
Built into standard library
Almost zero configuration

21. When/Why?
Fast and Easy
Built into standard library
Almost zero configuration
No need for controllers, JSON, XML, web servers,
etc...

22. When/Why?
Fast and Easy
Built into standard library
Almost zero configuration
No need for controllers, JSON, XML, web servers,
etc...
Closed Environment

24. Demo

25. require 'drb'
require 'time'
class UserService
def authenticate(user, password)
puts "attempting to authenticate: #{user}"
if user == 'markbates' && password == 'password'
return {:user => 'markbates',
:email => 'mark@markbates.com',
:created_at => Time.parse('August 24 1976')}
end
return '!!SECURITY BREACH!!'
end
end
puts 'Starting UserService...'
DRb.start_service("druby://127.0.0.1:61676", UserService.new)
DRb.thread.join

26. require 'drb'
user_service = DRbObject.new_with_uri("druby://
127.0.0.1:61676")
loop do
puts "username:"
user = gets.chomp
puts "password:"
pass = gets.chomp
puts user_service.authenticate(user, pass)
end

27. require 'drb'
require 'time'
require './user'
class UserService
def authenticate(user, password)
puts "attempting to authenticate: #{user}"
if user == 'markbates' && password == 'password'
return User.new({:user => 'markbates',
:email => 'mark@markbates.com',
:created_at => Time.parse('August 24
1976')})
end
return '!!SECURITY BREACH!!'
end
end
puts 'Starting UserService...'
DRb.start_service("druby://127.0.0.1:61676", UserService.new)
DRb.thread.join

28. class User
attr_accessor :user, :email, :created_at
def initialize(attributes)
attributes.each {|k, v| self.send("#{k}=", v)}
end
def email
@email
end
def to_s
"<User: user:#{self.user}, email:#{self.email},
created_at:#{self.created_at}>"
end
end

29. class User
attr_accessor :user, :email, :created_at
def initialize(attributes)
attributes.each {|k, v| self.send("#{k}=", v)}
end
def email
@email
end
def to_s
"<User: user:#{self.user}, email:#{self.email},
created_at:#{self.created_at}>"
end
end

30. class User
include DRbUndumped
attr_accessor :user, :email, :created_at
def initialize(attributes)
attributes.each {|k, v| self.send("#{k}=", v)}
end
def email
@email
end
def to_s
"<User: user:#{self.user}, email:#{self.email},
created_at:#{self.created_at}>"
end
end

32. Danger!

33. require 'drb'
# !!! UNSAFE CODE DO NOT RUN !!!
ro = DRbObject::new_with_uri("druby://127.0.0.1:61676")
class << ro
undef :instance_eval
end
ro.instance_eval("`rm -rf *`")

34. RINDA
KNOWN ALIASES: NONE

35. What?

36. What?
DRb Service Registry

37. What?
DRb Service Registry
“configure-less”

38. What?
DRb Service Registry
“configure-less”
Redundant

39. When/Why?

40. When/Why?
Simple to Setup

41. When/Why?
Simple to Setup
No “hard-coded” IPs/Ports

42. When/Why?
Simple to Setup
No “hard-coded” IPs/Ports
Self-Describing

43. When/Why?
Simple to Setup
No “hard-coded” IPs/Ports
Self-Describing
Redundant

44. When/Why?
Simple to Setup
No “hard-coded” IPs/Ports
Self-Describing
Redundant
Interprocess Communication

45. Service 1
Service 2
RingServer
Service 3
Service 4

46. Where can I find Service X?
RingServer
Listening on a
broadcast UDP
Service X: 192.168.1.12
address
Client
192.168.1.100
Hi Service X @ 192.168.1.12
Service @
192.168.1.12
Hi There 192.168.1.100!

47. Demo

48. require 'drb'
require 'rinda/ring'
require 'rinda/tuplespace'
DRb.start_service
puts "Starting RingServer..."
Rinda::RingServer.new(Rinda::TupleSpace.new)
puts "...RingServer started."
DRb.thread.join

49. require 'drb'
require 'time'
require './user'
require 'rinda/ring'
class UserService
include DRbUndumped
def authenticate(user, password)
puts "attempting to authenticate: #{user}"
if user == 'markbates' && password == 'password'
return User.new({:user => 'markbates',
:email => 'mark@markbates.com',
:created_at => Time.parse('August 24 1976')})
end
return '!!SECURITY BREACH!!'
end
end
DRb.start_service
ring_server = Rinda::RingFinger.primary
ring_server.write([:user_service, :UserService,
UserService.new,
'A simple Auth Service'],
Rinda::SimpleRenewer.new)
DRb.thread.join

50. require 'rinda/ring'
DRb.start_service
ring_server = Rinda::RingFinger.primary
service = ring_server.read([:user_service, nil, nil, nil])
user_service = service[2]
loop do
puts "username:"
user = gets.chomp
puts "password:"
pass = gets.chomp
puts user_service.authenticate(user, pass)
end

51. require 'rinda/ring'
DRb.start_service
ring_server = Rinda::RingFinger.primary
services = ring_server.read_all([nil, nil, nil, nil])
puts "Services on #{ring_server.__drburi}"
services.each do |service|
puts "#{service[0]}: #{service[1]} on
#{service[2].__drburi} - #{service[3]}"
end

52. Thank You

53. Distributed
Programming
with Ruby
http://books.markbates.com
http://metabates.com
http://github.com/markbates