Migrating VB 6 Applications to VB .Net

Nilotpal BhattacharyaPartner Technical Consultant| Microsoft

Agenda

►Why VB .NET?►Migration Decision Framework►Migration Strategies►Migration Tools►Demos

► Move towards Object Orientation► Many great language features► Better and powerful IDE► Awesome XML support► Disconnected data architecture► Web programming support► Easy deployment► Plenty of resources and full support

Why VB .NET?

Rewrite Migrate

Replace/Partner

Reuse

Application Quality

Ap

pli

cati

on

TY

pe Custom

Standard

HighLow

Migration Decision Framework

Migration Strategies

Client Tier

Business Tier

Data Tier

Component vs. Horizontal vs. Vertical Migration

Horizontal

Com InteropComponent

Vertical

Form

In

tero

p

Using COM from .NET

Potential issues with RCW

►Object RuntimeComponents that assume deterministic finalization may “leak” resourcesDestrcutors or Class_Terminate events will not execute untill the object is being collected

Marshalling TypesCustom marshalling/serlialization of complex types may be required

Try to expose simple types (string, integers, dates when possible

Runtime Callable Wrapper

DEMO

Using .NET from COM

Restrictions with CCW

Classes must have a default constructor (One that takes no parameter)Classes cannot expose shared methodsClasses cannot expose overloaded methods

Note: If you expose overloaded methods, then you’ll get non descriptive names in the CCW (e.g Hello and Hello_2

Using .Net from COM

DEMO

Interop Forms Toolkit 2.0Reduce risks by moving one form at a time instead of entire modules or tiersExtend existing VB Forms with VB .Net ControlsProvides guidance, tools and code to make phased upgrade easierNot a code converterVB 6 Application

VB6 Form(s)Com Interop

VB .NET Form(s)

Features in v2.0

Interop UserControlsNet Controls that look and feel like ActiveX controlsExtend VB6 apps within the same formCan be placed in MDI

Easy DeploymentRedistributableRegFree COM SupportMore Documentation

Interop ToolKit v2.0

DEMO

►Code AdvisorAdd-in for VB6Review code against pre-determined standardsIdentify migration issues

►Upgrade Assessment toolFile Dependency and Call graphsEstimates of cost and effort to migrateOther potential migration issues

MigrationTools

►EXE & DLL►Copies project►Creates reports► Links to Help► Four Levels

Issue No Automatic UpgradeToDo Requires Finishing Warning Possible Behavior ChangeNote Informational

MigrationMigration Wizard

Tools

DEMO

► Install Visual Basic 6.0 on the computer that you will be using for upgrading.

►Windows Forms is largely compatible barring few differences like► Non compatible Clipboard statements ► No support for the Name property for forms

and controls at run time► Setting 0 in Timer control to disable the

Timer.►Get an estimate by running Upgrade

Wizard

Some Pointers for migration

►Mainstream support ended March 31, 2005

7 years of free support is far longer than competitors

►Extended support is available through March 31, 2008. Custom support through 2012

► The VB6 Runtime is slated to ship as a part of Windows Vista

FAQ – VB Support policyHow much longer are you supporting VB6?

Resources

► “Upgrading VB6 to VB.NET” MS Press – FREE !http://msdn.microsoft.com/en-us/vbrun/ms788236.aspx

► Designing an Application Migration Strategy…http://msdn.microsoft.com/en-us/library/aa288720.aspx

► Upgrade Assessment tool and Upgrade guidehttp://msdn.microsoft.com/en-us/library/aa480541.aspx

► Preparing your Visual Basic 6 Applications for Upgrade

http://msdn.microsoft.com/en-us/library/aa260644.aspx

► Code Advisorhttp://www.microsoft.com/downloads/details.aspx?familyid=a656371a-b5c0-4d40-b015-0caa02634fae&displaylang=en

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