From Desktop to Web : Revamping a Legacy Application with ASP.NET Core MVC

The world of software development is constantly evolving. Legacy desktop applications, while once at the forefront, can become cumbersome and limit accessibility. In this article, I'll share my experience revamping a legacy desktop application into a ASP.NET Core MVC web application. I'll also discuss the challenges I faced and the solutions I implemented to overcome them.

Challenge 1: Understanding Legacy Code

Problem: The original Windows application was built using outdated technologies and had extensive code dependencies, making it difficult to understand the existing logic and workflows.

Solution: I conducted a thorough code review, creating detailed documentation to map out the application's functionality. Pairing this with refactoring techniques allowed me to break down complex functions into manageable parts. This process not only clarified the existing code but also helped in identifying areas for improvement.

Challenge 2: Authentication Transition

Problem: The legacy Windows application posed a challenge as it functioned as a single-instance, single-user system, relying on a basic sign-in form that simply checked credentials against a database. Migrating to a web environment necessitated a complete overhaul of the authentication process.

Solution: I implemented ASP.NET Web API along with JWT (JSON Web Tokens) for secure authentication. This not only improved security but also allowed for stateless user sessions, enhancing scalability.

Challenge 3: User Experience Overhaul

Problem: The user interface of the legacy application was not user-friendly, lacking responsive design principles.

Solution: I redesigned the UI using Razor Pages in ASP.NET Core MVC, incorporating responsive design frameworks (Bootstrap). This transition provided a seamless experience across devices. User feedback was invaluable during this process, guiding iterative design improvements. (Some simple functionalities required multiple user interactions on legacy system which was improved in revamped web application)

Challenge 4: Data Handling and Migration

Problem: Migrating from MySQL to PostgreSQL presented several challenges, particularly regarding data type schema changes. MySQL and PostgreSQL handle certain data types differently, which led to potential incompatibilities during the migration process. For instance, MySQL’s AUTO_INCREMENT was replaced with PostgreSQL’s SERIAL, and there were differences in handling BOOLEAN and TEXT types.

Solution: I created a comprehensive mapping document that outlined the differences between MySQL and PostgreSQL data types. This helped in systematically converting data types during migration. During the migration, I utilized the pgLoader tool, which automatically converted the MySQL schema into PostgreSQL-compatible formats, adjusting data types as necessary.

Conclusion

Revamping a legacy Windows application into an ASP.NET Core MVC application is not without its challenges. However, with a structured approach to understanding the legacy code, enhancing security, improving user experience, managing data migration, and incorporating modern web features, I was able to create a robust and scalable application. This project not only enhanced my technical skills but also deepened my appreciation for the importance of modern development practices.