Legacy VC++, Com based Desktop application to Modern web with microservices

Question

I am in the process of moving my existing desktop application to web. The GUI is developed using MFC/VC++ and the buisness logic is written in COM enabled VC++ DLL. This Dll has various responsibilities. Currently this Dll is loaded as part of the desktop application memory.Now I am in the initial stage of moving this application to modern web application. Below is the thought process for design considered till now,

1. Converting monolithic business logic to micro services.
2. Deploy the micro services in a server.
3. My business logic VC++ Com layer can interface with microservices and get data.
4. Have a API gateway which can communicate to microservices and it can serve to the web client.

In this process I wanted to reuse VC++ Com business logic layer as much as possible. The current com Dll is not supporting multi threading or multi user sessions. This needs to be supported. The next thing would be reusing existing MFC GUI in web.

What are the technologies can be considered to reuse my buisness logic?

Answer 1

For the most code-reuse I think you're on the right track.

You definitely want to separate out the business logic into it's own service and you can expose that via any communication protocol you prefer. The biggest downside to this is that every time functionality needs to be added, it needs to be added in two places, or in this case three: the business logic server, the MFC server, and the web server.

As others have pointed out, MFC was really intended for desktop applications. A "modern web application" is one that is stateless and communicates via message-passing over http(s) with the web browser being the client. There's really no re-using the MFC GUI in the web. The architectures are just too disconnected.

Having said that, and I haven't looked into it too much, but Blazor is a WASM compiler. It has limited support for the .net framework, even less so around the communication portion of it, but it might be able to compile your project. I'd bet against it, however.

I think you'd be better off just focusing on a decent web experience with a SPA and abandoning the MFC/Desktop portion. Maybe later you can circle back and build a GUI through MAUI or WPF that consumes the web API.