Project Overview

The end client was using a business-critical desktop application developed in VB6 running on Windows 7. To improve maintainability, ensure scalability, and achieve compatibility with modern environments, we migrated the application to the VB.NET language.

This initiative has enabled the stable and continuous operation of the system.

Technology Stack and Development Tools

• Programming Languages: VB6, VB.NET
• Backend Framework: .NET Framework
• Database: PostgreSQL 9.3.4
• Database: Oracle
• Task Management Tool: Backlog
• Communication Tool: Backlog
• Other Tools: GrapeCity Spread, Inputman, Crystal Reports

The Client’s Challenges

• The application was designed for Windows 7, which is no longer supported, necessitating a migration to a system that could run on modern operating systems.
• Support for the VB6 development environment had ended, requiring a move to VB.NET to mitigate risks.

The Client’s Requirements

A Complete and Compliant Migration from the Existing System

The client’s key requirements for the system development partner were as follows:

• The new system must guarantee functionality equivalent to the current system, completely inheriting all existing features and business processes.
• The source code must adhere to the client’s established coding conventions.

Our Proposal and Approach

Automation of the Migration Process

To optimize cost and time, we automated the migration process. Specifically, we developed a proprietary migration support tool to efficiently and accurately convert the large volume of source code. This improved operational efficiency and shortened the implementation period.

This tool was able to streamline the entire workflow, from parsing VB6 syntax and auto-converting it to VB.NET, to verifying the code after conversion.

Migration Based on Business Understanding

We ran the existing system and conducted a detailed analysis of its business workflows to confirm that the new system could perfectly replicate all its functions.

Source Code Standardization and Optimization

The original VB6 system did not adhere to a unified programming standard. Therefore, in addition to directly converting the source code from VB6 to VB.NET, we also conducted code reviews, standardization, and refactoring after the conversion.

This process significantly improved the new system’s maintainability