How to migrate a VB6 application

This post is a quick overview of an Abto Software blog article.

Visual Basic – a well-known programming language that’s losing its popularity and slowly getting abandoned. Despite enjoying enormous application across industries – healthcare, retail, finance & banking, construction – the environment has been already marked for death.

In this detailed guide, we’ll discuss the process of moving from legacy VB6 applications to modern .NET code.

Migrating legacy VB6 applications: getting started

Step 1: don’t underestimate internal evaluation

A thought-out VB6 to .NET migration strategy begins with initial internal evaluation, typically including:

Codebase analysis

At first, you have to perform codebase analysis to understand application complexity and maintainability:

• Assess the code size & structure
• Assess the code complexity
• Identify any external libraries, COM components, ActiveX controls, as well as other third-party services
• Look for code duplicates/redundancy – these areas are candidates for refactoring

Performance assessment

Next thing, you have to conduct performance assessment to identify code bottlenecks and malfunctions:

• Measure the application’s efficiency in its current state
• These metrics can serve as benchmarks to compare application versions
• Assess the application’s efficiency speaking about resource utilization
• Detected problems might signal the areas for optimization

User feedback

Moving further, gather feedback to highlight usability issues, desired improvements, underused functionality, and other common problems:

1. Identify your user groups
2. Include your key stakeholders
3. Analyze historical support tickets, bug reports, or complaints
4. From collected user feedback, identify common pain points
5. Ensure the user feedback is aligned with your strategic goals
6. Evaluate feasibility
7. Group the user feedback
8. Prioritize the user feedback

Feature Assessment

And finally, remember conducting feature assessment to categorize existing functionality:

1. Create a detailed inventory of all the features
2. Analyze the usage patterns
3. Identify any obsolete features that must be retired
4. Determine any missing features that have been requested
5. Ensure the business logic behind features is relevant
6. Assess dependency between features and components

Step 2: think about business needs & objectives

A successful VB6 to .NET migration strategy unfolds with addressing business goals, which means:

• Ensuring the application migration supports broader business goals, for example, better performance
• Including key business stakeholders to clarify the expectations
• Analyzing inefficiencies & frustrations with the current system to address in the migration process
• Defining needs & objectives to prioritize in the migration process
• Estimate time and costs, allocate resources, and determine the milestones
• Identify risks, create detailed mitigation plans, and plan for rollback

Step 3: moving further – the strategy

When approaching VB6 to .NET conversion, you will be choosing between strategies, for example:

• Code migration – code conversion making minimal code changes
• Code rewriting – code rebuilding from scratch without reusing code parts
• Code rearchitecting – only partial code redesign while retaining core functions
• And many other options

Step 4: what about resource allocation?

When planning VB6 to .NET conversion, you just cannot skip resource-allocation planning, so calculate:

• What is the current application complexity?
• What is the business-critical application functionality that must be preserved?
• What is our budget for the migration project?
• What is the timeline for the prospective project, and what are the critical milestones?
• How will we ensure business continuity during migration?
• What are the needs for maintenance and support after migration?

Migrating legacy VB6 applications: our approach

Code assessment and inventory

When handling VB6 migration, we start with initial code analysis – size, structure, code complexity, and more. This enables scope estimation, meaning outlining the budget and timeline, tasks, roles, deliverables, activities, and potential project challenges.

For successful VB6 conversion, we catalog the elements – forms, classes, COM components, ActiveX controls. This enables the identification of components that don’t have equivalents.

Code conversion

To handle the transition, we’ll utilize specialized tools, which requires us to carefully review:

• .NET support
• Legacy APIs
• Conversion strategy and accuracy
• And other critical characteristics

And having done that, we’ll proceed with the following tasks:

• Initial setup & configuration
• Automated conversion
• Careful review
• Manual intervention

Thorough testing and trouble-shooting

At this project stage, we cover extensive testing and debugging to ensure the software is working as expected.

In particular, we assess:

• Data integrity
• Business logic
• Database queries and interactions
• Error messages and alerts
• Performance benchmarks
• Exception handling

Additional optimization and refactoring

At this project stage, we cover code optimization and refactoring to ensure its performance in the first place.

In particular, we address:

1. Network latency
2. Resource overuse
3. Slow queries and interactions
4. Excessive connections
5. Inefficient algorithms
6. Inefficient looping or recursion

Application deployment

After covering code assessment and inventory, code conversion, and other critical stages, we get to deploy. Data disparity, broken integrations, runtime errors, system downtime, layout issues, authentication problems – arising challenges are handled right away.

Post-migration maintenance and support

And finally, after delivering the product, we might also provide ongoing support and maintenance if required. That means security updates and patching, compatibility checks, and more.

Summing up

Abto Software offers expertise in transitioning mission-critical applications, no matter the industry and scope.

Our engineers can manage every stage, including discovery and planning, code assessment and preparation. Our clients forget about operational and performance issues, security vulnerabilities, compatibility problems, and other common shortcoming coming with outdated technology.

We cover:

• Business analysis and consulting
• Project setup and kick-off
• Code migration
• Code finalization
• Acceptance testing and improvement
• Quality assurance and deployment

You enjoy:

• Higher performance and efficiency
• Expanded functionality and scalability
• Improved security through updates and patches
• Enhanced compatibility across platforms and devices
• Long-term support and maintenance
• Cloud compatibility