VB'NET

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Best Practices for Upgrading VB 6.0 Projects to
VB.NET Peter Ty Developer Evangelist .NET and
Developer Group
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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Code
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Introduction to VB.NETWhat is VB.NET?

• Next Generation of Visual Basic
• Two New Forms Packages
• Removed Legacy Keywords
• Improve Type Safety
• Exposing Low-Level Constructs for Advanced
  Developers
• Fully Integrated With Other Visual Studio.NET
  Languages

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Introduction to VB.NETDesign Goals of VB.NET

• Rapid .NET Application Creation
• Deliver the features you requested
• Modernize
• Simplify
• Reduce Programming Errors
• Solve the deployment problem
• Provide full access to the .NET Frameworks

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Introduction to VB.NETWhy is VB.NET not 100
compatible?

• Two Design Issues
• Retrofit existing code
• Building new code from ground up
• Interoperability
• A major goal to ensure Visual Basic code could
  fully interoperate with C or VC
• VB.NET is a true Object-Oriented Language
• Removed unintuitive and inconsistent features

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Introduction to VB.NETUpgrade Roadmap

• Upgrading Is Not A Requirement
• Leave Existing Code in VB 6.0
• Continue developing in VB 6.0
• Or interoperate between VB 6.0 and VB.NET
• Upgrade to VB.NET
• Considerations
• Application Architecture and Technologies
• Maintenance or New Development

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Introduction to VB.NETReasons To Upgrade

• Maximized Productivity
• Task List, Class View
• New project types
• NT Services
• Console Apps
• Error checking as-you-type
• First Class Object-Oriented Constructs
• Inheritance
• Structure exception handling
• Parameterized constructors

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Introduction to VB.NETReasons To Upgrade

• Windows Forms
• Visual inheritance
• Control anchoring, in-place menu editor
• Connected and disconnected databinding
• Web And Server Features
• Web forms
• Web services
• RAD for the server
• Better Deployment
• No DLL
• Builds .msi and .cab setup programs

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Introduction to VB.NETReasons To Upgrade

• Power Features
• Multi-threading
• Debugging across all languages
• Built From The Ground-up on .NET Framework
• Direct access to .NET classes
• Code access security
• ADO.NET and XML

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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Code
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Upgrading to VB.NETUsing The Upgrade Wizard

• Included With Visual Basic.NET
• Upgrades VB 6.0 Projects Opened in VB.NET
• Creates new Visual Basic.NET project
• Existing VB 6.0 project left unchanged
• Upgrade Tool Focus
• Language syntax changes
• VB 6.0 Forms, user controls
• Middle Tier Components
• WebClasses

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Upgrading to VB.NETManual Upgrade

• ActiveX Documents
• DHTML ActiveX Designer
• DAO and RDO Data Binding
• OLE, Shape Control
• Non horizontal, vertical lines
• Property Pages
• Add-In Extensibility
• Language Features
• LSet, ObjPtr, VarPtr, StrPtr
• GoSub Return, Computed Goto

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Upgrading to VB.NETTODO Comments

• Assist Developers When
• Items can not be automatically upgraded
• Behavior differences
• Summarized in Upgrade Report

'VB6 Dim o As Object Set o Me.Text1 o "Hello
World"
'Visual Basic.NET Dim o As Object O
Me.Text1 'UPGRADE_WARNING Couldn't resolve
default property of object o o "Hello World"
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Demonstration 1Using Visual Basic Upgrade
Wizard Step-By-Step Upgrade Wizard
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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Codes
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Leveraging Existing CodesRuntime Type System

• CLR Compilers use the Runtime Type System to
  produce type compatible components

Runtime Components
PlatformCompilers

C
VB
C
Runtime Type System
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Leveraging Existing CodesCOM Interoperability
Services
Type SystemStandard
BinaryStandard
Runtime Execution Sys
COM Binary Std
C
VB
MFC/ATL
MSVCRT
C
Runtime Type System
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Leveraging Existing CodesWhy Interop?

• Preserve/Utilize Your Investment
• No need to start over
• Continue to use exist code
• Incremental Migration Path
• Migrate your application step by step
• Reality Some Things Never Change
• Need to interop with code that cant change

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Leveraging Existing CodesBridging Different
Worlds

• Unmanaged Code
• Binary standard
• Type Libraries
• Immutable Types
• DLL Hell
• Interface based
• HResults
• Guids

• Managed Code
• Type Standard
• Metadata
• Resilient Bind
• Assemblies
• Object based
• Exceptions
• Strong Names

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Leveraging Existing CodesInterop Services

• COM Interop
• Use COM components from the runtime
• Use .NET Framework components from COM
• Platform Invoke
• Call static Entry Points in unmanaged DLLs
• Pass function pointers to unmanaged code for
  callback

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Leveraging Existing CodesBi-Directional COM
Interop

• .NET to COM
• Allows .NET types to access COM types
• COM to .NET
• Allows COM types to access .NET types

.NET
COM
COM
.NET
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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Codes
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Architectural GuidanceBrowser-based Applications

• ASP.NET
• Services for all web applications
• Authentication, Caching, State Services
• Web Services
• Web Forms
• The best of Web Classes and ASP
• Separates UI and code
• Familiar development model
• Full, compiled Visual Basic language
• Target any browser on any platform

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Demonstration 2Browser Based Application
Create a Hello World Web Application
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Architectural GuidanceClient/Server Applications

• Visually Compose Business Objects
• Manage Enterprise Wide Programmer Resources
• Easy Scalable, Transacted, Cross-Machine, And
  Cross-Platform Messaging
• Easily Create Windows Services
• Configure And Diagnose Your Production
  Applications

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Architectural GuidanceSingle-tier Applications

• Visual Inheritance
• Delivers features you have asked for
• Visual inheritance, in-place menu editor,
  printing
• Accessibility
• Anchoring and docking, MDI enhancements
• Interoperability through the .NET Framework
• Designed for expansion
• Extender controls

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Architectural GuidanceData Model

• Scalability, Interoperability By Default
• DataAdapter
• Pulls data into a DataSet
• Pushes data modifications back to database
• Full programmatic control over queries
• DataSet
• No knowledge (or limitation) of data source
• Disconnected and move between tiers as XML
• Program against strongly-typed objects
• Design time support for multi-tier data access

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Demonstration 3Data Model Using ADO.NET
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Architectural GuidanceWeb Services

• First VBXs, Then COM, Now Web Services
• Creation Is Easy
• WebMethod Subs and Functions
• VS automatically publishes to the Web
• Drag-And-Drop Consumption
• Discovery via Web References, Server Explorer
• As simple as calling a method

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Demonstration 4Web Service Hello World Web
Service
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Architectural GuidanceDeployment

• No More DLL Hell
• Enabled by the .NET Framework
• Side-by-side, XCOPY, no restarting IIS,
  versioning
• Windows Installer Technology
• Self repairing installations, advertising,
  rollback, digital signing
• Transacted, custom action authoring
• Remote Install Of Web Applications, Services,
  Server Resources

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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Codes
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Programming Recommendations Variant to Object

• VB 6
• Variant special universal data type

• VB.NET
• Object the universal data type used by Common
  Language Runtime

Dim x As Variant
Dim x As Object
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Programming RecommendationsVariant Conversion

• VB 6
• Should Var1 and Var2 be added as strings or
  integers?

• VB.NET
• Avoid using variant
• Use explicit conversions

Var3 Var1 Var2
Var3 CInt(Var1) CInt(Var2)
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Programming Recommendations Integer To Short ,
Long To Integer

• VB 6
• Long 32-bit
• Integer 16-bit

• VB.NET
• Long 64-bit
• Integer 32-bit
• Short 16-bit

Dim x As Integer Dim y As Long
Dim x As Short Dim y As Integer
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Programming Recommendations Currency To Decimal

• VB 6
• Currency 64-bit hybrid

• VB.NET
• Decimal provides better accuracy

Dim x As Currency
Dim x As Decimal
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Programming Recommendations Date To Date

• VB 6
• Date stored internally in Double format

• VB.NET
• Date 64-bit integers

Dim dbl As Double Dim dt as Date dbl dt
Dim dbl As Double Dim dt as Date dbl dt.ToOADate
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Programming Recommendations Property Syntax

• VB 6
• GET, LET and SET can be declared with different
  level of accessibility

• VB.NET
• GET and SET must have the same level of
  accessibility

Property Get .. Public Property Let .. Friend
Property Get .. Private Property Set .. Private
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Programming Recommendations VB Forms to Windows
Forms

• VB 6
• Has own forms package for creating graphical
  applications

• VB.NET
• Windows Forms generic forms package for Common
  Language Runtime

Visual Basic Forms
Windows Forms
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Programming RecommendationsEarly-Binding

• VB 6
• Declaring a variable as Object datatype and
  assigning it at run time

• VB.NET
• Declare variables of the appropriate object type

Dim o As Object Set o Me.Label1 o.Caption
"SomeText"
Dim o As Label Set o Me.Label1 o.Caption
"SomeText"
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Programming Recommendations Parameterless
Default Properties

• VB 6
• Declaring a variable as Object datatype and
  assigning it at run time

• VB.NET
• Declare variables of the appropriate object type

MsgBox Me.Text1 rs("CompanyName") "SomeCompany"
MsgBox Me.Text1.Text rs("CompanyName").Value
"SomeCompany"
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Programming Recommendations Avoid Null
Propagation

• VB 6
• Supports Null propagation

• VB.NET
• Does not support Null propagation
• Always check for Null

V 1 Null V Null Right("SomeText", 1) V
Right("SomeText", 0)
IsNull()
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Programming RecommendationsUse Zero Bound Arrays

• VB 6
• Can define arrays with lower and upper bounds of
  any whole number

• VB.NET
• Must have a lower bound of 0
• Cant use ReDim unless the variable was
  previously declared

Dim a(1 To 10) As Integer Dim v ReDim v(10)
Dim b(10) As Integer ReDim b(5) As Integer
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Programming RecommendationsConstants vs.
Underlying Values

• VB 6
• Can assign any constants or values

• VB.NET
• Use constants rather than relying on their
  underlying values

Me.WindowStyle 2
Me.WindowState vbMaximized
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Programming RecommendationsArrays and
Fixed-Length Strings

• VB 6
• Fixed-length strings are supported in the language

• VB.NET
• Fixed-length strings are no longer supported in
  the language

Private Type MyType MyArray(5) As Integer
MyFixedString As String 100 End Type
Private Type MyType MyArray() As Integer
MyFixedString As String End Type
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Programming RecommendationsAvoid Legacy Features

• Removed from the language
• Deflttypegt
• Computed GoTo/GoSub
• GoSub/Return
• Option Base 01
• VarPtr, ObjPtr, StrPtr
• LSet

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Programming RecommendationsWindows APIs

• Most API can be used exactly as they were in VB
  6.0
• Remove the As Any by replacing the Declare with
  two versions
• Upgrade APIs to .NET components manually

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Programming RecommendationsForms and Controls

• Does Not Support OLE Container Control
• No Shape, Line Control
• New Graphics Commands Replacing Old Form Methods
• 2 Menu Controls MainMenu and ContextMenu
• Does Not Support DDE

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Programming RecommendationsForms and Controls

• Does Not Support Form.PrintForm Method
• VB 6.0 Drag-And-Drop Properties and Methods
  Cannot Be Upgraded
• Clipboard Statements Cannot Be Automatically
  Upgraded
• Windows Forms Does Not Support Name Property
• Use Default ScaleMode Of Twips

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Agenda

• Introduction to VB.NET
• Upgrading to VB.NET
• Leveraging Existing Codes
• Architectural Guidance
• Programming Recommendations
• Taking the Next Step

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Taking The Next StepFree Threading

• All Objects Can Be Called From Any Thread
• Similar to multi-threaded appt objects
• Types Of Synchronization Mechanisms
• SyncLock control structure
• Use of framework synchronization classes
• Synchronized Context
• Only one method of the set of objects within the
  same synchronized context can execute at a time
• Thread Synchronized Context
• Same but methods are always executed on the same
  thread

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Taking The Next StepDelegate

• Object Oriented Function Pointer
• Can Reference Both Static and Instance Methods
• Points To A Specific Method Of A Specific
  Instance
• Type Safe and Secure

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Taking The Next StepAttributes

• A way associating extra information with
  assemblies, classes, class members, parameters,
  and return types
• Many Predefined Attributes
• Function ltWebPublic()gt Deposit()
• Class ltObsolete()gt HumanTeller
• ltAssembly AssemblyVersion(1.0.0)gt
• New Attributes Can Be Defined By Classes That
  Inherit From System.Attribute

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Taking The Next StepStructure Error Handling

• Eliminates need for GoTo
• Throw Statement
• Generates typed exception Supports typed
  exceptions
• Try Construct
• Guarded code between Try and first Catch
  statement
• Catch Statements
• Filters on type or general condition
• Finally Block
• Always executed

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Taking The Next StepInheritance

• Inheriting Classes Easily Broken When Base Class
  Changes
• By Default Methods Are Not Overridable
• Overriding Is Explicit Using Overrides Keyword
• Shadows Keyword Used To Hide Inherited Members
• Classes Can Be Declared As NotInheritable

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Taking The Next StepOverloading

• Two Or More Methods With Same Name But Different
  Parameter Types
• Subs and Functions
• Shared and Instance Methods
• Two Or More Properties With Same Name But
  Different Parameter Types
• Overloading Can Be Done In Structures, Classes,
  And Interfaces

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Taking The Next StepOverriding

• Overriding Replaces Inherited Implementation Of
  Method Or Property
• An Overriding Methods Parameter Types Must Match
  Exactly
• Even when cast to base class, Calling Method
  Executes New Implementation (Polymorphism)

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Taking The Next StepShadowing

• Member Of Derived Class Can Shadow All Members Of
  Base Class With Same Name
• This is the default behavior but a warning is
  generated
• Shadows keyword makes it explicit
• The kinds of the members in the base and derived
  classes dont matter

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Demonstration 5Inheritance and Override
Inheritance Example 1Inheritance Example 2
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Taking The Next StepReduce Programming Errors

• Parameterized constructors
• Variables can be initialized where declared
• Circular References
• Garbage collector recovers instances in reference
  cycles
• Decimal type replaces Currency

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Taking The Next StepObject Performance

• Reference Assignment For Arrays
• Array1 Array2
• Instance Size Much Smaller
• Faster Object Manipulation
• Faster creation
• Faster assignment
• Supports direct data member access

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Session Summary

• VB.NET offers new features
• A true object-oriented programming language
• Closely integrated with the .NET Framework
• Interoperable with existing VB 6.0 projects

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For More Information

• MSDN Web Site at
• msdn.microsoft.com
• VB.NET Upgrade Information Sites at
• msdn.microsoft.com/vstudio/nextgen/Technology/vbup
  grade.asp
• msdn.microsoft.com/library/techart/vb6tovbdotnet.h
  tm
• msdn.microsoft.com/vbasic/technical/upgrade/downlo
  ad.asp

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