1. Informatics 122 Alex Baker
Design Recovery 1
Informatics 122
Alex Baker

2. What is Design Recovery?
Sort of like reverse engineering

3. What is Design Recovery?
Design recovery recreates design abstractions from
Code
Existing design documentation (if available)
Personal experience / general knowledge about problem and application domains
Talking to people
(Biggerstaff, 1989)

4. What is Design Recovery?
Recovered abstractions need:
Formal specifications
Module breakdowns
Data abstractions
Dataflows
Informal knowledge
All information required to understand
What
How
Why
(Biggerstaff, 1989)

5. Also like a double-waterfall…
General model for recovery (Byrne, 1992)
Alteration
Reverse
Engineering
Abstraction
Con-
ceptual
re-think
Con-
ceptual
Forward
Engineering
Refinement
re-specify
Requirements
Requirements
re-design
Design
Design
re-build
Implementation
Implementation
Existing System
Target System

6. Why do we need to know this?
Working with others’ code…
Debugging
Maintenance
Reuse
Working with your own code

7. Motivation: No design Lost design Build-and-fixed Agile methodologies
Incomprehensible design

8. Motivation: Design Drift

9. Motivation: Design Drift
Design not followed

10. Motivation: Design Drift
Design not followed

11. Motivation: Design Drift
Design deviations

12. Motivation: Design Drift
Design deviations ?

13. Motivation: Design Drift
Design deviations

14. Motivation: Design Drift
Design deviations
???
???

15. Motivation: Design Drift
Design deviations
???
???

16. Motivation: Design Drift
Design deviations
???
???

17. Motivation: Design Drift
Design deviations

18. Motivation: Design Drift

19. Motivation: Design Drift
???

20. Motivation: Design Drift
???

21. Design Recovery in Diamond
Dom Materials
Domain of Use
Knowledge
Rep (Code)
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

22. Design Recovery in Diamond
Someone made a design…
Dom Materials
Domain of Use
Knowledge
Representation
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

23. Design Recovery in Diamond
Someone used that to create code (fairly rotely)
Dom Materials
Domain of Use
Knowledge
Rep (Design)
Rep (Code)
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

24. Design Recovery in Diamond
You get ideas from the code
But do the captures relationships hold?
Dom Materials
Domain of Use
Knowledge
Rep (Code)
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

25. Design Recovery in Diamond
So when you modify the code, who knows?
Dom Materials
Domain of Use
Knowledge
Rep (Code)
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

26. Could even be your own code
You’ve often recovering, in some sense
???

27. Also, remember Design recovery recreates design abstractions from Code
Existing design documentation (if available)
Personal experience
General knowledge about problem and application domains

28. Design Recovery in Diamond
Every part is involved
Dom Materials
Domain of Use
Knowledge
Representation
Ideas
Activity
concern
manipulates
informs
captures
Goal
enhances

29. Isn’t this Reverse Engineering?
Not just recreating the UML diagram…
Program flows
Rationale
Metaphor

30. Also like a double-waterfall…
General model for recovery (Byrne, 1992)
Alteration
Reverse
Engineering
Abstraction
Con-
ceptual
re-think
Con-
ceptual
Forward
Engineering
Refinement
re-specify
Requirements
Requirements
re-design
Design
Design
re-build
Implementation
Implementation
Existing System
Target System

31. Finding the structure (not the same as the design)
Entities
Classes
Methods
Variables
Relationships
Inheritance
Method calls
References

32. Approaches Reverse engineering tools Reading documentation
E.g. Omondo
Reading documentation
Code reading
Reading class names
Talking to people
Want to point out that you can learn a lot from just reading the file names, what patterns are used, what sorts of classes you’re using – and it’s a way to see everything at the high level – importance of making these good

33. But where’s the design? What principles were applied?
What were their priorities?
What patterns emerged?
What actual patterns were used?
This will save you a lot of trouble

34. An example: Jetris

35. Jetris Design Recovery
Run the game
Reading names
What is HTMLLink?
What is Figures.java?
What’s with those arrays?
What about the big classes?
Omondo

36. What will you actually create?
It depends:
How difficult?
Who else?
The future…

37. The other side of the coin…
How easy is your program to understand?
How is your:
Documentation
Naming
Code
Goes at the end somewhere

38. Assignment 4 Recover the design of Cake Each group: Each group member:
Layered design environment, uses Archstudio’s BnA Framework
You may use any tools you like
Each group:
A Complete UML (-ish) Diagram
Each group member:
A 4-6 page double-spaced paper explaining your understanding of the program’s design, including patterns, principles etc.
Must provide good high and low level explanation
Due Sunday at Midnight
to and
Paper copies in class on Monday

39. Possible subjects What types of classes appear
What do they do? What do they mean?
What do other specific classes do?
How to they all relate?
How is layering implemented?
What was the effect of using BnA in the design?
What principles might have guided the design?

40. Some tips
Won’t have room for rote completeness, will need to be elegant
Use representations of classes to organize
Look for implements relationships

41. Useful links Archstudio Source Descriptions for BnA Package Classes
Descriptions for BnA Package Classes
BNA Hierarchy