Measurement Metrics for Object Oriented Design

1. A Metric Suite for Object Oriented Design Shyam R. Chidamber and Chris F. Kemerer Ari Wibisono BambangAdhi AchmadRohman

2. Outline

3. Contribution

4. Research Probelms

5. Theoritical Criticism

6. OO design and development.

7. Objective

8. Theory Base for OO Metrics

9. Measurement Theory Base

10. Empirical Data Collection

11. Software Dev Organization

12. Results

13. Metric 1 : Weighted Method Per Class

14. Character Graphics

15. Matrix 1 : Weight Method per Class Case Study : Character Graphics Number of Class Observed : 8 Number of Method Observed : 59

16. How TO ObserveD

17. Cyclomatic complexity

18. Weight Method per Class (Statistics)

19. Weight Method per Class (Character Graphics)

20. WMC Result Cyclomatic Complexity Testability Understandability (SATC 1995)

21. Matrix 3 : Depth of Inheritance Tree DIT is the maximum length from a node to the root (base class) Viewpoints: Lower level subclasses inherit a number of methods making behavior harder to predict Deeper trees indicate greater design complexity

22. Matrix 2 : Depth of inheritance Tree

23. Matrix 2 : Depth of inheritance Tree

25. Viewpoints:

26. As NOC grows, reuse increases - but the abstraction may be diluted

27. Depth is generally better than breadth in class hierarchy, since it promotes reuse of methods through inheritance

28. Classes higher up in the hierarchy should have more sub-classes then those lower down

31. the number of other classes that are referenced in the class C (a reference to another class, A, is an reference to a method or a data member of class A)

32. Viewpoints:

33. As collaboration increases reuse decreases

34. High fan-outs represent class coupling to other classes/objects and thus are undesirable

35. High fan-ins represent good object designs and high level of reuse

37. Matrix 4 : Class between objects

38. Metric 5: Response For a Class (RFC)

40. Dan jikabanyak method dapatdipanggiluntukmeresponspesan yang diterimaolehsebuahobyekdarisuatu class besarkemungkinanpemeliharaandan testing menjadilebihkompleks.

41. Responsuntukmetriks class bertujuanuntukmengukurbanyaknya method lokaldanbanyaknya method yang dipanggiloleh method lokal

43. RFC = |RS| dimana RS adalah himpunan respons untuk class yang diberikan

44. RS = {M} Uall i {Ri}

45. dimana {Ri} = himpunan method-method yang dipanggil oleh method i dan

46. {M} = himpunan semua method-method dalam class

47. Ilustrasi definisi di atas :

48. A::f1() memanggil B::f2()

49. A::f2() memanggil C::f1()

50. A::f3() memanggil A::f4()

51. A::f4() tidak memanggil method lain

52. Then RS = {A::f1, A::f2, A::f3, A::f4} U {B::f2} U {C::f1} U {A::f4}

54. Metric 5: Response For a Class (RFC)

55. Metric 6: Lack of Cohesion in Methods (LCOM)

57. Metriks LCOM adalahnilaiketidaksamaan method-method dalamsebuah class

59. Terdapatsebuah class C1 dengan n method M1, M2, …, Mn. Dengan {Ij} = himpunanvariabel instance yang digunakanoleh method Mi. Terdapatsebanyak n himpunan {I1}, …, {In}. Dengan P = {(Ii, Ij) | Ii ∩ Ij = ø} dan Q = {(Ii, Ij) | Ii ∩ Ij ≠ ø}. Jikasemuahimpunan n {I1}, …, {In} adalah ø makakemudian P = ø.

60. LCOM = |P| - |Q|, if |P| > |Q|. Otherwise LCOM = 0

63. Metric 6: Lack of Cohesion in Methods (LCOM)

65. FabrizioRiguzzi:"A Survey of Software Metrics", UniversitàdegliStudidi Bologna, July 1996

66. Lionel Briand, Khaled El Emam, SandroMorasca :"On the Application of Measurement Theory in Software Engineering",International Software Engineering Research Network technical report #ISERN-95-04

68. Norman Fenton:"Software Measurement: A Necessary Scientific Basis", IEEE TRANSACTIONS ON SOFTWARE ENGINEERING. VOL. 20, NO. 3, MARCH I994 I99

69. Everald E. Mills : “ Software Metrics”, SEI Curriculum Module SEI-CM-12-1.1, Software Engineering Institute, Carnegie Mellon University, December 1988

71. Conclusion Dalampengevaluasianmetrikinidenganmencocokandengankriteriastandar, hal yang dicocokanyaitu : Memilikisejumlahproperti yang diinginkan. Menyarankanbeberapacaradimanapendekatan OO mungkinberbedadalamhalfiturdesain yang diinginkanataudiperlukandaripendekatantradisional.

72. Conclusion Clearly, future or further research are designed to further investigate these apparent differences seem necessary.