This document discusses migrating a Visual Smalltalk application to VisualWorks. It outlines the migration process, including creating a baseline, translating code to run in VisualWorks, testing to ensure the same behavior, building the runtime, and improving the codebase. Key steps are resolving undeclared references, addressing differences in the GUI and base classes, writing tests, and taking advantage of VisualWorks features once the migration is complete.

1. Migration from VSE to VW with Pollock
Christian Haider

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Overview
• Motivation
• Migration Process
• The Baseline
• Migration details
• Conclusions

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Why this talk?
• Smalltalk market
• VSE is dead
• Pollock comes
• As a checklist for VSE projects
• Tell you that it is easy and worth it
• My experience
• 2 private projects
• 1 consulting project

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Why migrate?
• Why migrate
• Worry about support for new Windows versions
• “System gets cracks”
• New features
• More Platforms
• Increase Productivity
• Why not to migrate
• Cost of VisualWorks
• Cost of migration
• GUI migration is now easier with Pollock
• Cost of change
• Migrate to where?
• VW, VA, Java, C#

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How to migrate
• Only migrate – don’t improve!
• The Project is migrating, not just the Code
• Get a Consultant
• Customer will do everything!
• Consultant will explain, guide and help where appropriate
(and keep the fingers off the keyboard :-)
• Setting
• One Table with one Keyboard and Mouse
• Display with a Beamer
• Start with visual.im
• Enhance the VisualWorks environment as needed
• Consultant provides help and explanations when useful

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Situation
Visual Smalltalk
App
Superclass
-Instvars
-classvars Globals
External
Classes
Classes
Classes
Database Comm.
VisualWorks
App
Superclass
-Instvars
-classvars Globals
External
Classes
Classes
Classes
Database Comm.

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Porting Steps - Overview
1. Create a Baseline (same source)
2. Translate Code (runnable code)
3. Test (same behavior)
4. Build Runtime (same product)
5. Make it Nice (new possibilities)

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Baseline
• Defined state
• Equivalent Source
• Same module structure and versions
• All sources and texts are integrated and
published in Store
• Loads without serious warnings
• All work can be done in VisualWorks

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Towards the Baseline
Get all Sources into VisualWorks
• Module Structure…
• Namespace Name
• External Interfaces…
• FileIn Modules…
• Publish Baseline
• Load in fresh image

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Store Bundle Structure
• The Store structure should reflect the development process
• If a Team/V repository exists, the same structure should be used
• Suggestion:
Application Development
(VSE Porting)
Application Runtime
Common
Module 1
…
Module n
Tools
Tests
• Define a version format (1.0.0.0 <major.minor.revision.build>)
• An Access DB can be used nicely as light weight Store

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External Interfaces
• DLL calls
• <api: name args return>
• Sockets
• Use VW
• Database
• Use VW
• COM?
• SmallCOM/X?
• Other?

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Environment
• Tool to fileOut XML VW sources
• VSE Porting package
• VSE namespace
• VSE.Class
• VSE.DynamicLinkLibrary with api parser
• Tools package
• Browser list icons

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FileIn
1. Open GHChangeList
• Precondition: Undeclareds are empty
• Set default namespace and encoding
2. Load all sources for one package
3. Replay all
• Missing superclasses -> define as VSE.Class
• External interfaces -> define as VSE.DynamicLinkLibrary
4. Resolve Undeclared…
5. Add text file comments to Pundles, Classes and Globals
6. Publish to Store

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Resolving Undeclareds
• Referenced class
• Subclass VSE.Class
• Global, pool constant
• Add Shared Variable in VSE (move to porting package)
• Instvar, class instvar, class var
• add in VSE.Class subclass
• Global in system extension
• Shared variable in referring Class (move to porting package)
• Instvar in system overwrite
• Add as temp var and add a comment/marker

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The Migrant
• Missing references are resolved (empty porting package)
• Message send but not implemented issues are resolved
• The code loads without warnings
• Clean-up
• The code critic reports no bugs or possible bugs.
• There are no unnecessary system extensions or overrides
• There is no unused code
• The system and the applications run basically correct.
• Problem areas are identified, recorded and patched
• The behavior of the VSE system is basically preserved

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Towards the Migrant
• Eliminate the porting package
• Resolve former Undeclareds
• Resolve ‘Methods send but not implemented’
• Options
• Rewrite Tool (!)
• Regex
• Reimplement
• Remove
• Publish and load in fresh image often

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Topics
• Translation by topics
• Files
• Registry
• TCP/IP
• Processes
• Exceptions
• Finalization
• C calls
• Dependency mechanism
• GUI…

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Differences in the Base
• (Smalltalk at: #...)
=> (‘namespace.global’ asQualifiedReference value)
• TimeStamp => Timestamp
• Colors: Color, RGBColor, logical colors => ColorValue
• Pool constants (Clr*, Cr, Lf) => ColorValue, Character, …
• File access: File, Directory, Disk => Filename
• ObjectFiler => BOSS
• Application startup: SessionModel, SmalltalkLibrary,
SmalltalkLibraryBinder => ObjectMemory, Parcel

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GUI Migration
• Emulate or replace?
• Port one existing GUI
• Get the topics with the debugger
• Change them generally with the rewrite tool

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Differences in the GUI
• CursorManager, MessageBox , Prompter
=> Dialog
• PrinterDialog [Windows Goodies],
FontDialog
• Display, Bitmap, Images, Icons
• Text, Fonts
• Window opening
• Windows messages: wm*

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GUI differences
AbstractPaneVisualPartSubPane
ControllerControllerWindows events
Window #opened(model)#needsContents
FormSubCanvasNesting: own pane
UserInterfaceApplicationModelViewManager
PollockWrapperDigitalk

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Pollock Model
Pane
Agent
Artist
Frame

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Widgets
--ImageList
--StatusWindow
--StatusField
PageTabControlPage
TreeViewTreeView
DropDownListComboBox
TextEditRichEdit
TextEditTextPane
InputFieldEntryField
DisplayTextStaticText
ToolItemSeparatorToolbarSeparator
ButtonButton
ToolbarButtonToolbarToggleButton
ToolbarButtonToolbarButton
ToolbarToolbar
TabControlTabControl
ListBoxListBox
RadioButtonRadioButton
CheckBoxCheckBox
GroupBoxGroupBox

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Adding a Widget
• VSE • Pollock
listBox := ListBox new.
listBox font: self defaultFont.
listBox printSelector: #printItem.
listBox when: #changed:
send: #setSelection: to: self.
listBox when: #needsContents
send: #setList: to: self.
frame := LayoutFrame
topLeftRatio: 0 @ 0
bottomRightRatio: 1 @ 1.
listBox layoutFrame: frame.
view addPane: listBox.
listBox := ListBox new.
listBox textStyle: self artist listStyle.
listBox displaySelector: #printString.
listBox when: #selectionChanged
send: #setSelection: to: self.
frame := FractionalFrame
fractionLeft: 0 top: 0
right: 1 bottom: 1.
listBox frame: frame.
window addComponent: listBox.

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Tests
Resolve the remaining differences
• Module tests
• SUnit test
•First in VSE
•Then migrate to VW
• Application tests

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Runtime and Performance
• Build Runtime
• RTP bug: exit on last window close
• Test Runtime
• Test Performance (WTS)

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Make it Nice
• Separate development from runtime
• Structure namespaces
• Define protocols (if not Team/V)
• Comment Pundles, Classes, Globals (if not Team/V)
• Write your formatter
• Make use of VW Features
• MultiProc-UI
• Opentalk, CORBA
• Net and Web Support
• .net and CE Support (in Beta)
• Pollock

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Conclusion
• It is easy and can be done in a few weeks
• All code is rewritten and looked at
• Duplications
• Nil disease
• Coding Style
• Forgotten code
• Direct variable access
• Branches
• Long methods

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Recommended Tools
• StoreForAccess (lightweight on disk)
• GHChangeList (adds Namespace and package support)
• Coding
• Refactoring Browser
• Rewrite Tool
• Regex Tool
• Code Critic
• SUnit (standard for module tests)
• Environment
• RBCodeHighlighter (highlights while typing)
• RBTabs (avoids too many browsers)
• AutoComplete
• RBSUnitExtensions (adds SUnit buttons to the browser)
• RBStoreExtensions (shows versions graphically)
• ExtraIcons (nice list icons, essential for testing)
• WinIcons (icons for VW tools)