Francesco Balena's speech at Basta! 2010 conference in Germany on September 22nd: VB6-to-NET Migration: Myth, Truth, and Real-World Experiences

1. Francesco Balena – Code Architects, Italy VB6 Migration: Myth, truth, and real-world experiences

3. MSDN Regional director, Italy

4. VB Migration Partner

6. the only Microsoft ISVNXT partner specialized in conversion and modernization of VB6 apps

7. customers in Europe, United States & Canada, Australia and Asia

8. dozens of millions of lines of code migrated

10. port & extend

11. rewrite

12. “language impedance”

13. functional equivalence

15. “language impedance”  data types  type-char suffix  Array lower bounds  Optional params  As New variables  Byval argument passing  Defxxx  array rank  missing As  As Any parameters  block variables  date as double  array assignments  callbacks in Declare  As New arrays  UDT initialization  Variants  default parameterless members  Gosub  On Goto/GoSub  Byref ParamArray  Fixed-length strings  UDT assignments  byte-oriented string functions  enum/number conversions  IsMissing  Empty value  Null propagation  VarPtr, ObjPtr, StrPtr  class termination  IDisposable objects  default members in late-binding  OLE control  Line and Shape controls  control arrays  graphic methods  ScaleMode property  DrawMode property  DAO and RDO data-binding  ADO data-binding  ADO data-bound classes  DataEnvironment  VBControlExtender object  PropertyPages  UserDocuments  “classic” drag-and-drop  OLE drag-and-drop  Extender and Ambient properties  DDE  WebClasses  DHTML Pages  Sub Main in DLLs  SingleUse classes  Global classes  COM+ components  class persistence  Print and Printers  App, Screen, Forms objects  ActiveX EXEs  popup menus 

16. “language impedance” (UW)  data types  type-char suffix array lower bounds Optional params As New variables  Byval argument passing  Defxxx array rank  missing As  As Any parameters  block variables  date as double  array assignments  callbacks in Declare  As New arrays  UDT initialization  Variants  default parameterless members  Gosub  On Goto/GoSub  ByrefParamArray  Fixed-length strings  UDT assignments  byte-oriented string functions  enum/number conversions  IsMissing  Empty value  Null propagation  VarPtr, ObjPtr, StrPtr class termination  IDisposable objects  default members in late-binding  OLE control  Line and Shape controls  control arrays  ScaleMode property  DrawMode property  DAO and RDO data-binding  ADO data-binding  ADO data-bound classes  DataEnvironment VBControlExtender object  PropertyPages  UserDocuments  “classic” drag-and-drop  OLE drag-and-drop  Extender and Ambient properties  DDE  WebClasses  DHTML Pages  Sub Main in DLLs  SingleUse classes  Global classes  COM+ components  class persistence  Print and Printers  App, Screen, Forms objects  ActiveX EXEs  popup menus 

17. “language impedance” (VBMP)  data types  type-char suffix  array lower bounds  Optional params  As New variables  Byval argument passing  Defxxx  array rank  missing As  As Any parameters  block variables  date as double  array assignments  callbacks in Declare  As New arrays  UDT initialization  Variants  default parameterless members  Gosub  On Goto/GoSub  ByrefParamArray  Fixed-length strings  UDT assignments  byte-oriented string functions  enum/number conversions  IsMissing  Empty value  Null propagation  VarPtr, ObjPtr, StrPtr  class termination  IDisposable objects  default members in late-binding  OLE control  Line and Shape controls  control arrays  graphic methods  ScaleMode property  DAO and RDO data-binding  ADO data-binding  ADO data-bound classes  DataEnvironment  VBControlExtender object  PropertyPages  UserDocuments  “classic” drag-and-drop  OLE drag-and-drop  Extender and Ambient properties  DDE  WebClasses  DHTML Pages  Sub Main in DLLs  SingleUse classes  Global classes  COM+ components  class persistence  Print and Printers  App, Screen, Forms objects  ActiveX EXEs  popup menus 

18. truth rewriting from scratch can deliver the best quality code ( sad but true  )

19. myth rewriting from scratch always delivers the best quality code

20. truth the sooner we start, the better

21. myth the sooner we start, the better, therefore let’s run the Upgrade Wizard, remove all compilation errors, debug the .net code, do some tests, fix bugs, polish the UI, create the setup, write the manual, and tell the boss we’re ready to ship 

22. myth nearly all migration projects fail miserably

23. truth nearly all migration projects fail miserably if they weren’t planned accurately ( like any software project... )

24. what you need, what you have a goal what goes to .NET, what stays in VB6 architectural changes target language, 3rd-party controls a migration tool (if any) a deadline a team VB & .NET expertise, familiarity with the code base, migration skills

27. myth all .NET language are equally powerful, therefore it doesn’t really matter whether we select VB.NET or C# in our migration projects

28. VB.NET challenges Variants Null propagation in expressions ActiveX EXE components Gosub, VarPtr, StrPtr, ObjPtr

29. C# challenges Variants Null propagation in expressions ActiveX EXE components Gosub, VarPtr, StrPtr, ObjPtr optional parameters (fixed in 2010) late binding (almost fixed in 2010) error handling

30. C# challenges On Error Resume Next DoSomething(x) If CheckExpr(x) Then DoSomethingElse(x) try { DoSomething(x); } catch (Exception ex) { SetError(ex); } bool test; try { test = CheckExpr(x); } catch (Exception ex) { SetError(ex); } try { if (test) DoSomethingElse(x); } catch (Exception ex) { SetError(ex); }

31. myth (revised) all .NET language are equally powerful, therefore it doesn’t really matter whether we select VB.NET or C# in our migration projects ...unless you are paid by the hour 

32. myth migrated code runs slower than hand-written code

33. (half) truth migrated apps should never use a support library

34. myth migrated apps must never, ever use a support library

35. a support library can dramaticallyreduce compile and runtime errors closely mimic VB6 behavior and UI hide the complexity of .NET produce concise and neater code optimize your app for size/speed simplify bug fixes offer interoperability with VB6 apps ... (read more reasons here)

37. slidesavailable atwww.slideshare.net/VBMigrationPartner

38. blogwww.vbmigration.com/blog

39. LinkedIn Group on VB6 Migrationwww.linkedin.com/groups?gid=3074090

41. To learn more about your VB6 applications, run VB6 Analyzer on your source code and send us the generated text file.

42. You will receive a detailed report on your VB6 applications and how VB Migration Partner can help you to quickly and effectively migrate it to .NET.www.vbmigration.com/getfreeadvice.aspx