1. The Secret behind Google Docs,
Google Wave and Zoho Suite:
Operational
Transformation

2. Who I am
Matteo Collina
Twitter: @matteocollina
Website: matteocollina.com

3. What do I do?

4. I study a lot..
CCAC North Library http://www.flickr.com/photos/ccacnorthlib/3554627894/in/photostream/ CC by 2.0

5. ...and today I'll
speak about what
I've studied!
CCAC North Library http://www.flickr.com/photos/ccacnorthlib/3554627894/in/photostream/ CC by 2.0

6. We will see...

7. We will see...
1. Why Real Time is cool
2. Why we are solving the wrong problem
3. An algorithm to rule them all

10. is all about
interaction..

11. ..between people,

12. that acts through
Browsers,

13. that communicate
through a server!

16. We can create
new forms of
collaboration!

18. There are LOTS of
frameworks

19. There are LOTS of
frameworks...

20. ...and companies!

21. ...and companies!
Thanks!

22. The frameworks
are solving
1. How we present the data to the user
2. How to transfer the data on the wire

23. Where is the
interaction between
people?

24. What happens when
they change the same
document?

26. Really?

27. Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/

28. How can we
handle
conflicts?
Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/

29. Can users
understand
this?
Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/

31. We usually
lock our
documents
to protect
them!

32. Only the
user that
locked the
document
can edit it!

33. Some people are
doing it correctly..

34. Some people are
doing it correctly..
..how?

35. What happens when
we edit a document?

37. Insert(0,"hello ")
Delete(6, 5)
Insert(6,"world")

38. s = "jsday"
Insert(0,"hello ")
s = "hello jsday"

39. s = "hello jsday"
Delete(6, 5)
s = "hello "

40. s = "hello "
Insert(6,"world")
s = "hello world"

41. The operations
are processed
as they arrive:
what happens if
there are more
users sending
them?

42. What happens if the
operations come from
two users?

44. sA = "hello world" sB = "hello world"

45. What happens if
operations get
delayed?
sA = "hello world" sB = "hello world"

47. sA = "hello jsday" sB = "hello world"

50. Operational
Transformation

51. Operational
Transformation
➡ has been a research topic for
more than 20 years
➡ is a family of algorithms
❖ Jupiter has lead to Google
Docs / Wave

52. Operational
Transformation
1. reorders the operations
2. handles the conflicts
between operations
3. garantees the same result
on all nodes

53. Reorder Problem

54. How can we reorder
the operations?

56. What is the
intention behind
the delete?

57. s = "hello jsday" The intention
behind the
Delete(6, 5) delete is to
remove the
"jsday" string
s = "hello "

58. Delete(6, 5) Delete'(12, 5)
Insert(6,"world")

59. Delete(6, 5) Delete'(12, 5)
Insert(6,"world")
OT transposes the Delete
through the Insert

61. s = "hello worldjsday"
Delete'(12, 5)
s = "hello world"

62. s = "hello worldjsday"
OT is about
changing where
Delete'(12, 5)
and how the ops
are = "hello uted
s exec world"

63. What happens
if two users delete
the same string?

64. What happens
if two users delete
the same string?
Delete(6, 5) NoOperation
Delete(6, 5)

65. Operational
Transformation
reorders the operations
handles the conflicts
between operations
garantees the same result
on all nodes

66. Unfortunately,
there is some nasty
math involved!

67. DEMO!!!
http://www.flickr.com/photos/oneaustin/1261907803

68. markdocs.com

69. TL;DR
http://www.flickr.com/photos/evilaugust/3307382858

70. TL;DR
Operational transformation:
• allows to build true real time
applications;
• is really hard;
• garantee the same results for
every users!
http://www.flickr.com/photos/evilaugust/3307382858

71. Check out realify.it!

72. ..but we started
with a question!

73. What do I do?

74. What do I do?
• Ph.D. Student
• Software Engineer @ Mavigex
• Conference Speaker (?)

75. Choose your tools wisely!
http://www.flickr.com/photos/chuffy/186676221

76. Thank You!

77. Any Questions?