The slideshow I used to defend my Computer Science M.S. Thesis, which at the time of the defense had a terrible title that was later officially changed to Planning-Based Approach for Automating Sequence Diagram Generation.

1. Planning Messages in Sequence Diagrams and
Analyzing the Consistency of Use Cases and
Class Diagrams Automatically using Design by
Contract
MS Thesis Defense
Yaser Sulaiman
Advisor
Dr. Moataz Ahmed
December 29, 2012

2. title
“I made this [letter] very long, because I did not have the
leisure to make it shorter.”
—Blaise Pascal
2
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3. Under the right conditions,
sequence diagram generation is a
planning problem
3

4. 4
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5. Background
Sequence Diagram Generation as a Planning Problem
Literature Review
Research Questions
Communiqué: A Library for Planning Messages in Sequence Diagrams
Experiments
Conclusions
5
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6. Background
6
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7. Function
System
Structure Behavior
7

8. Use Cases
Sequence
Diagrams
System
State
Class
Transition
Diagrams
Diagrams
8

9. Class Sequence
Use Case
Diagram Diagram
vs.
Use Case
Sequence
Diagram
Class
Diagram
9

10. Design by Contract (DbC)
10

11. 11
Photo by my brother Maher

12. The C in DbC
Contracts (preconditions +
postconditions) semantically specify
the relation between routines & callers
12

13. DbC (Eiffel) in Action
-- A pop routine of a limited-capacity
-- stack.
pop(): T
require
not empty
do
..
ensure
not full
count = old count - 1
end
13

14. Object Constraint Language (OCL)
UML DbC OCL
14

15. OCL in Action
-- Assuming Stack has Boolean
-- isEmpty() & isFull() methods &
-- integer count attribute.
context Stack::pop(): T
pre: not self.isEmpty()
post: not self.isFull() and
self.count = self.count@pre - 1
15

16. Automated Planning
s0 a1 s1 a2 s2 a3 … ag sg
Σ = (𝑆, 𝐴, 𝛾)
16

17. s0 a1 s1 a2 s2 a3 … ag sg
17

18. Forward State-Space Search
s0 … sg
18

19. Backward State-Space Search
s0 … sg
19

20. Languages
Design by Contract Automated Planning
Stanford Research Institute Problem Solver
Eiffel
Action Description Language
Object Constraint Language
Planning Domain Definition Language
20

21. PDDL in Action
(:action pop
:parameters (?s Stack)
:precondition (> (count ?s) 0)
:effect (decrease (count ?s) 1)
)
21

22. Sequence Diagram Generation as a Planning Problem
22
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23. Correspondence between Planning
and DbC
Automated Planning Design by Contract
Initial State Use Case Preconditions
Goal Use Case Postconditions
Actions Methods
Action Preconditions Method Preconditions
Action Effects Method Postconditions
23

24. States as Object Diagrams
24

25. s0 a1 s1 a2 s2 a3 … ag sg
25

26. Literature Review
26
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27. Paper Focus Main Idea
A parser to translate a manually normalized use case to
Liwu Li (2000) Model Generation
message records
Köster, Six & Winter Using refined activity diagrams to couple use cases & class
Consistency Analysis
(2001) models
Using set theory & first-order logic to check consistency
Li, Liu & He (2005) Consistency Analysis
between the use case model & the conceptual class model
Using a queue & BFS to detect inconsistencies between well-
Long et al. (2005) Consistency Analysis
formed class & sequence diagrams
A context-free grammar for use case, activity & class
Chanda et al. (2009) Consistency Analysis
diagrams
Yue, Briand & A systematic review focusing on transforming textual
Model Generation
Labiche (2010) requirements to analysis models in the context of MDD
Yue, Briand & A technique to automatically derive analysis models from
Model Generation
Labiche (2010) use cases while maintaining traceability links
Ghezzi, Mocci & Using symbolic model checking to cross-validate algebraic
Consistency Analysis
Salvaneschi (2010) specifications against intensional behavior models
Using the B method to automatically analyze the consistency
de Sousa et al. (2010) Consistency Analysis
of requirements
RE & Automated
Vaquero et al. (2011) itSIMPLE: an IDE for automated planning applications
Planning
Sulaiman & Ahmed RE & Automated Using itSIMPLE to demonstrate treating sequence diagram
(2012) Planning generation as a planning problem
27

28. Vaquero et al.
Requirements &
Automated
Knowledge
Planning
Engineering
Sulaiman & Ahmed
28

29. Message Receiver Parameter
0: (LOGIN PROFILE) [1]
1: (ACTIVATE ACCOUNT PROFILE) [1]
2: (WITHDRAW ACCOUNT PROFILE AMOUNT) [1]
3: (LOGOUT PROFILE) [1]
But what about the Sender?
29

30. Research Questions
30
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31. Q1: How can sequence diagrams be automatically
generated from DbC’ed use cases and class diagrams?
Q2: How can that process be used to analyze the
consistency between use cases and class diagrams?
Q3: Which contract language should be used to enable
those processes?
Q4: How do the automatically-generated sequence
diagrams compare to the manually-generated ones?
31

32. Communiqué: A Library for Planning Messages in Sequence Diagrams
32

33. Available on Github
http://git.io/communique
Implemented in
Ruby
Logo by Yukihiro Matsumoto 33

34. Use Case
Sequence
Communiqué
Diagram
Class Diagram
Instance
34

35. 35

36. Forward-search(s0, g)
n ← [s0, the empty plan]
Enqueue(n, f(n))
until queue is empty
s, π ← Dequeue-min()
if s satisfies g then return π
applicable ← {m | precond(m) is true in s}
if applicable = ϕ then next
for each m ϵ applicable
n ← [γ(s, m), π.m]
Enqueue(n, f(n))
return failure
36

37. s0
…
…
… …
… …
…
sg
37

38. The Evaluation (or Objective)
Function
Cost so far; depth of n; # of previous message passes
−& 𝑔 𝑛 , &&&&&&&&&&&&DFS
𝑓 𝑛 = &𝑔 𝑛 , &&&&&&&&&&&&BFS
&𝑔 𝑛 + ℎ 𝑛 , A∗
Estimated cost to goal; estimated # of remaining message passes
38

39. h(n) = # objects not satisfying their
goals
39

40. h(n) is not admissible: it may
overestimate the cost of reaching
the goal
40

41. h(n) non-admissibility
⇒
planner non-optimality
41

42. To determine the sender of a
message, Communiqué uses the
links between the objects along with
some rules of thumb
42

43. Sender-Selection Assumptions
The Actor initiates the use case
Boundary objects interact with the Actor
Dependent objects are responsible for the objects they
create
A sender must already be active
A sender must have a link to the receiver
43

44. OCL-Like Ruby Expressions for
Pre- & Postconditions
context Stack::pop(): T
pre: not self.isEmpty()
post: not self.isFull() and
self.count = self.count@pre - 1
pop = DbcMethod.new(:pop)
pop.precondition = Proc.new { self.is_empty? }
pop.postcondition = Proc.new { @count -= 1 }
44

45. Experiments
45
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46. The original models were not
DbC’ed; I added what I believed to
be commonsense contracts
46

47. Experiment #1
Simple Sequence Diagrams
47

48. Properties Management System* –
Class Diagram
* Aman et al. Senior Project 48

49. Add Property Modify Property
Select Featured Property Delete Property Modify Announcement
49

50. Experiment #2
More Complex Sequence Diagrams
50

51. Weather Station System* – Class
Diagram
* Ian Sommerville. Software Engineering 51

52. Weather Station System –
Sequence Diagram
Textbook’s Diagram Communiqué’s Output
52

53. 2Bwatch* – Class Diagram
* Bruegge and Dutoit. OOSE using UML, Patterns & Java 53

54. 2Bwatch – Sequence Diagram
54

55. Did you notice something wrong?
55

56. 56

57. I didn’t*.. until I saw Communiqué’s
output
* After all, I’m not a software engineer 57

58. Textbook’s Diagram Communiqué’s Output
58

59. There is no association to support sending refresh() as
it appears in the book’s sequence diagram
59

60. Now, what would Communiqué do?
60

61. Textbook’s Diagram Communiqué’s New Output
61

62. “You’re doing
it wrong!”
62
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63. Textbook’s Diagram Communiqué’s New Output
63

64. “Success!”
64
Photo used with permission from Laney G

65. Experiment #3
Effects of Noise
“Irrelevant” methods
65

66. Always applicable
Does nothing
66

67. These methods has an effect similar
to that of a large class diagram
67

68. MeetingsMate* – Class Diagram
* Al Akel et al. Senior Project 68

69. MeetingsMate – Sequence Diagram
69

70. 70

71. 71

72. 72

73. # of noise methods
DFS explored 𝑂(𝑚) states, but the solution was of
length 𝑂(𝑚)
BFS found the optimal solution, but it explored
𝑂(𝑐 𝑚 ) states
Best-first search explored 𝑂(𝑚) and found the
optimal solution
73

74. Experiment #4
Non-Optimality of Communiqué’s
Best-First Search
74

75. h(n) non-admissibility
⇒
planner non-optimality
75

76. 76

77. Optimal Diagram Communiqué’s Output
77

78. f(n) = g(n) + h(n)
s0 0+3
prepare_to_satisfy_all_objects_at_once() satisfy_objects_1_and_2()
1+3 s1 s2 1+1
satisfy_all_objects_at_once() prepare_to_satisfy_object_3()
2+0 sg1 s3 2+1
satisfy_object_3()
sg2 3+0
78

79. f(n) = g(n) + h(n)
s0 0+3
prepare_to_satisfy_all_objects_at_once() satisfy_objects_1_and_2()
1+3 s1 s2 1+1
satisfy_all_objects_at_once() prepare_to_satisfy_object_3()
2+0 sg1 s3 2+1
satisfy_object_3()
sg2 3+0
79

80. Experiment #5
Object Instantiation
80

81. Oh how meta!
81

82. 82

83. Experiment #6
Failure Handling
83

84. If Communiqué fails to find a
solution, it points to possible
sources of inconsistencies
84

85. 85

86. 86

87. Conclusions
87
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88. Action Planners Message-Passing
Communiqué
Action Planners
Planner
Typically, predefined
State Representation A set of objects
state variables
Specification OCL-like
OCL-like Ruby
STRIPS, ADL, or PDDL
Language expressions
Preconditions plus
Constraints Preconditions only semantic class
relationships
Creation of New State
Typically, not supported Object instantiations*
Components
88

89. Limitations*
* “It’s not a bug; it’s a feature.” 89

90. Instantaneous State Transitions
90

91. Sender-Selection Inaccuracies
Textbook’s Diagram Communiqué’s Output
91

92. Other Limitations
Non-Optimality of Communiqué’s Best-First Search
Limited Message Types
Limited Actor Support
No Support for Combined Fragments
Not Comparing States for Equality
Possible Bias in Experiments
Using Ruby for Inputs and Raw Outputs
92

93. Future Work
Handle Time Explicitly
Design a Better Heuristic
Try Other Planning Algorithms &
Approaches
Use XMI for Inputs and Outputs
93

94. …</presentation>
<questions>…
94

95. Sender-Selection Rules
1. If the message is the 1st in the sequence of
message passes, select the Actor.
2. If the receiver of the message is a boundary
object, select the Actor.
3. If the receiver of the message is a dependency
object, select the object’s creator.
4. If the message has more than one candidate
sender, select the most recently activated
candidate sender.
5. If the message does not have any candidate
sender, select the Actor.
95