Interfaces are not created equal. Upon reaching the summit of a releasable product it is easy to lose site of where you started. The disconnect grows as you explore how to build a bridge from internals to end users. Developing interfaces for others is one of the hardest things we do, but thankfully you are not alone. I have spent the last two years interacting with and creating interfaces to cloud services with fog. By exploring examples we can see patterns and establish best practices for APIs, CLIs and even library code.

1. Common sense is the
“ collection of prejudices
acquired by age
eighteen.
Albert Einstein

2. Assumptions
Probably
Incorrect

3. Assumptions
Probably
Incorrect

4. Assumptions
Probably
Incorrect

5. Assumptions
Probably
Incorrect

6. The secret to creativity
“ is knowing how to
hide your sources.
Albert Einstein

7. Beg (colleagues)
Borrow (peers)
Steal (competitors)

8. Beg (colleagues)
Borrow (peers)
Steal (competitors)

9. Beg (colleagues)
Borrow (peers)
Steal (competitors)

10. Beg (colleagues)
Borrow (peers)
Steal (competitors)

11. We cannot solve our
“ problems with the same
thinking we used when
we created them.
Albert Einstein

12. Peer review
Use cases
Beginner’s mind

13. Peer review
Use cases
Beginner’s mind

14. Peer review
Use cases
Beginner’s mind

15. Peer review
Use cases
Beginner’s mind

16. Design is the art of
“ gradually applying
constraints until only
one solution remains.
Unknown Author

17. Constraints
Formats
Protocols

18. Constraints
Formats
Protocols

19. Constraints
Formats
Protocols

20. Constraints
Formats
Protocols

21. Concern for man and his fate
“ must always form the chief
interest of all technical endeavors.
Never forget this in the midst of
your diagrams and equations.
Albert Einstein

22. Easy
Practical
Appropriate

23. Easy
Practical
Appropriate

24. Easy
Practical
Appropriate

25. Easy
Practical
Appropriate

26. Intellectuals solve
“ problems, geniuses
prevent them.
Albert Einstein

27. Tamper proof
PLA
Sensible defaults

28. Tamper proof
PLA
Sensible defaults

29. Tamper proof
PLA
Sensible defaults

30. Tamper proof
PLA
Sensible defaults

31. Any intelligent fool can make
“ things bigger and more
complex... It takes a touch of
genius - and a lot of courage to
move in the opposite direction.
Albert Einstein

32. Consistency
Modularity
Documentation

33. Consistency
Modularity
Documentation

34. Consistency
Modularity
Documentation

35. Consistency
Modularity
Documentation

36. Make everything as
“ simple as possible,
but not simpler.
Albert Einstein

37. Abstractions
Generalizations
Extractions

38. Abstractions
Generalizations
Extractions

39. Abstractions
Generalizations
Extractions

40. Abstractions
Generalizations
Extractions

41. Any man who can drive safely
“ while kissing a pretty girl is
simply not giving the kiss the
attention it deserves.
Albert Einstein

42. Doubt? Leave it out
One thing well
Separate concerns

43. Doubt? Leave it out
One thing well
Separate concerns

44. Doubt? Leave it out
One thing well
Separate concerns

45. Doubt? Leave it out
One thing well
Separate concerns

46. No amount of
“ experimentation can ever
prove me right; a single
experiment can prove me
wrong.
Albert Einstein

47. Whiteboard
Taste (dog food)
Fail fast

48. Whiteboard
Taste (dog food)
Fail fast

49. Whiteboard
Taste (dog food)
Fail fast

50. Whiteboard
Taste (dog food)
Fail fast

51. If you can’t explain it
“ simply, you don’t
understand it well
enough.
Albert Einstein

52. Assert
Communicate
Mentor

53. Assert
Communicate
Mentor

54. Assert
Communicate
Mentor

55. Assert
Communicate
Mentor

56. It’s not that I’m so
“ smart, it’s just that I
stay with problems
longer.
Albert Einstein

57. Questions?
Exceptions?
Doubts?

58. Questions?
Exceptions?
Doubts?

59. Questions?
Exceptions?
Doubts?

60. Questions?
Exceptions?
Doubts?

61. Wesley Beary
@geemus
Engine Yard

62. @geemus
More examples|notes:
!gist.github.com/1187182