1. Reverse Engineering and Design Recovery Informatics 122 Alex Baker

2. Definitions Reverse Engineering: Analyzing a system to: 1. Identify its components and their relationships 2. Create representations in another form  Usually refers to redocumentation Design Recovery  A subset of reverse engineering  A higher level understanding (Chikofsky and Cross, 1990)

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

4. What is the Design? The basics  Beast and Superbeast classes  AI classes  Data structure  Engine structure

5. What is the Design? We want a game based on Beast We want it to be expandable We must be able to add more monsters To enact this we want to use interfaces A lot of this is enacted through pushable Pushable is used by the engine to…

6. What if we want to… Change the double-beast-push behavior Add a new monster type Let the player climb on top of blocks Simplify the design

7. What is the Design? The basics  Beast and Superbeast classes  AI classes  Data structure  Engine structure

8. What is the Design? We want a game based on Beast We want it to be expandable We must be able to add more monsters To enact this we want to use interfaces A lot of this is enacted through pushable Pushable is used by the engine to…

9. What do we use? Reverse engineering recreates design abstractions from  Code  Existing design documentation (if available)  Personal experience / general knowledge about problem and application domains  Talking to people (Biggerstaff, 1989)

10. What do we Create? Recovered abstractions need:  Formal specifications  Module breakdowns  Data abstractions  Dataflows  Informal knowledge All information required to understand  What  How  Why (Biggerstaff, 1989)

11. Why do we have to do this?

12. Working with others’ code…  Debugging  Maintenance  Modification  Reuse Working with your own code You will work with code in the absence of a design

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

14. Motivation: Design Drift

15. Design not followed

16. Motivation: Design Drift Design deviations

17. Motivation: Design Drift Design deviations

18. Motivation: Design Drift Design deviations ?

19. Motivation: Design Drift Design deviations

20. ??? Motivation: Design Drift Design deviations ???

21. Motivation: Design Drift Design deviations ???

22. Motivation: Design Drift Design deviations ???

23. Motivation: Design Drift Design deviations ???

24. Motivation: Design Drift You’re often recovering, in some sense

25. Deviations happen Sometimes you’re formally making a spec Sometimes you’re just trying to figure out what the heck someone was thinking…

26. What are the Goals of RE Cope with complexity Generate alternate views Recover lost information Detect side effects Synthesize higher abstractions Facilitate Reuse (Chikofsky and Cross, 1990)

27. What are the Goals of RE Cope with complexity Generate alternate views Recover lost information Detect side effects Synthesize higher abstractions Facilitate Reuse Redocumentation Design Recovery

28. All this code What does it mean?

29. So lets start with the basics Recreating the structure (redocumentation) Existing SystemTarget System Implementation Design Requirements Con- ceptual Con- ceptual Design Implementation re-think re-specify re-design re-build Alteration Reverse Engineering Abstraction Forward Engineering Refinement

30. Object Orientation Something of an advantage  Class names, function names  Established relationships (inheritance, members, etc.) Cohesion

31. The Ideal Program (again) … vs.

32. Finding the structure Entities  Classes  Methods  Variables Relationships  Inheritance  Member Objects  Method calls

33. Approaches Reverse engineering tools  E.g. Omondo Reading documentation Reading class names Code reading Talking to people

34. Also, remember Existing artifacts, but also  Personal experience  General knowledge about problem  General knowledge about solution

35. goals In terms of our process model them Ideas (languages) representations (languages) you Ideas (languages) if(condition) functionCall(X); else functionCall(Y); goals knowledge

36. An example: Jetris http://jetris.sourceforge.net/

37. Reverse Engineering Jetris Multiple “passes”  Run the game  Reading names  What is HTMLLink? PublishHiScore?  What is Figures.java? FigureFactory?  TetrisGrid (wait, what’s with those arrays?)  AddFigure, dropNext, addFigureToGrid…  Actual loop? (nextMove)  UI

38. Goals and Knowledge Of Tetris Based on other artifacts (running program) Of tendencies? Patterns?

39. Lets get philosophical again!

40. Design Recovery in our Models Feasible Desirable Conceivable Outcome Space Design Space

41. Design Recovery (Product) Feasible Desirable Conceivable Outcome Space Design Space

42. Design Recovery (Product) Feasible Desirable Conceivable Outcome Space Design Space

43. Design Recovery (Product) Feasible Desirable Conceivable Outcome Space Design Space

44. Not Just the UML What principles were applied? What were their priorities? What patterns emerged? What actual patterns were used? What would developers making changes need to consider? This will save you a lot of trouble

45. Another (Small) Example addAllPixels(Image image){ for(int i = 0; i < image.getWidth(); i++){ for(int j = 0; j < image.getHeight(); j++){ Color c = image.getColor(i, j); addPixel(new Pixel(i, j, c)); addToColumn(i, new Pixel(i, j, c)); updateColorTotals(c); }}}

46. We might be able to guess that: Need for a pixel class Different instances for  addPixel  addToColumn Concerned about speed  Not so much about space Concerned about changability?  Or just following convention

47. Could have just been addAllValues(ImageNumber n){ for(int i = 0; i < image.height; i++){ for(int j = 0; j < image.height; j++){ colorArray[n][i][j] = image.colorAt(i, j); }}}

48. The other side of the coin… How easy is your program to understand?  The dual nature of code How is your:  Documentation  Naming  Code  Metaphor  Principles

49. Finally: What’s Actually Created? It depends:  How difficult?  Who else?  The future… Getting philosophical one last time

50. Design Recovery (Process) activities Ideas (languages) activities Ideas (languages) representations (languages) if(condition) functionCall(X); else functionCall(Y);

51. Design Recovery (Process) activities Ideas (languages) representations (languages) activities Ideas (languages) representations (languages) if(condition) functionCall(X); else functionCall(Y);

52. Design Recovery (Process) activities Ideas (languages) representations (languages) activities Ideas (languages) representations (languages) if(condition) functionCall(X); else functionCall(Y); goals knowledge

53. Finally: What’s Actually Created? It depends:  How difficult?  Who else?  The future… We could make  UML  UI map  Program flow  Description/Depiction of array metaphors  …

54. Assignment 3 – Design Recovery Recover the design of Palantír  Tool for awareness in configuration management systems developed at UCI  You may use any tools you like  Do not ask anyone about it (despite that normally being a good resource) Get the Palantír code from the subversion repository, detailed instructions follow

55. Assignment 3 – Design Recovery Each group must turn in:  A Complete* UML (-ish) Diagram  At least 1 additional diagram of your choice (might be informal)‏  A document describing the design of Palantír (at least 4 pages)‏  Your audience is someone unfamiliar with Palantír who needs to make very significant changes to it  The code may no longer compile!  Your submission graded on completeness, clarity, accuracy Each person also needs to submit a team evaluation (forms available on class webpage)‏ Paper copy due Monday, February 9 th, at start of class * see next slide

56. Assignment 3 – A Caveat on “Complete” Concentrate on (give complete design of) four packages:  edu.isr.palantir  edu.isr.palantir.core  edu.isr.palantir.server  edu.isr.palantir.ui Other packages and libraries are in the repository! (12)‏  They will be useful references in recovering the design.  You must check them out and use them in your analysis.  You do not need to fully recover their internal structure.  Represent them as amorphous blocks in your UML.  Be sure to show, e.g., calls that are made to them, from the four main packages.

57. Suggestions for Group Work Everyone start by taking their own look at the whole system  Multiple perspectives will be very useful Work out the high level architecture Concentrate on the four main packages Understand program flows Look out for subtle details

58. Further tips There are papers available on Palantír on André's website; feel free to consult them Use representations of classes to organize Rote completeness is not the answer, will need to be elegant

59. Team Assignments Team 1 Tomas Ruiz-Lopez Lance Cacho Daniel Morgan Scott Ditch Joshua Villamarzo Derek Lee Team 2 Alton Chislom Jeffrey Gaskill Matt Fritz James Rose Robert Duncan Team 3 David Schramm Leslie Liu Chad Curtis Alex Kaiser Ben Kahn Team 4 Jay Bacuetes Robert Jolly James Milewski Lance Zepeda Aylwin Villanueva Team 5 Alexander Doan Jordan Sinclair Rakesh Rajput Matt Shigekawa Scott Roeder

60. Detailed Checkout Instructions Two Steps: 1) Install Subclipse plugin for Eclipse 2) Check out the Palantír repository NB: this assumes that you're using Eclipse and are otherwise comfortable with it.

61. Detailed Checkout Instructions 1. In Eclipse, go to Help > Software Updates > “Available Software” tab

62. Detailed Checkout Instructions 2. Hit “add site”, enter location: http://subclipse.tigris.org/update_1.4.x

63. Detailed Checkout Instructions 3. Hit “OK” => Check the Subclipse main box => hit “Install”

64. Detailed Checkout Instructions 4. Make sure everything is checked off and hit “Finish”

65. Detailed Checkout Instructions 5. Let the libraries download => hit “Yes” at this dialogue box

66. Detailed Checkout Instructions 6. Make a new Project (NOT Java Project) and choose this

67. Detailed Checkout Instructions 7. Make a new repository location

68. Detailed Checkout Instructions 8. Enter http://tps.ics.uci.edu/svn/projects/palantir/trunk/ and hit “next”http://tps.ics.uci.edu/svn/projects/palantir/trunk/

69. Detailed Checkout Instructions 9. Select the root of the tree => hit “Next” (NOT “Finish”)‏

70. Detailed Checkout Instructions 10. Check out in the workspace => give it a name => hit “Finish”