We have a legacy desktop application that is built upon MFC way back and been used till date.
Using Desktop Bridge App Convertor I was now able to create appx for my legacy desktop app and I was able to install it and most of my functionalities are working as expected, except some.
How the converted app is working as my legacy app uses registries, which UWP apps will not have access as it is isolated environment? Also I don't see any registries post installation but the features work as expected, how is it done?
My legacy app finds certain devices using SNMP communication. Part of my functionalities which are through SNMP are working but one feature (Discovery) which also uses SNMP communication is not working. I doubt on capabilities as there is no scope here to declare while converting. Is that the only reason or any other issues?
If capabilities is the issue, how to declare those while doing conversion?
Your assumption that the converted MFC app lives in a sandboxed environment like a UWP app is wrong. See this:
Aside from the code that you use to light up Windows 10 experiences, your app remains unchanged and you can continue to distribute it to your existing Windows 7, Windows Vista, or Windows XP user base. On Windows 10, your app continues to run in full-trust user mode just like it’s doing today.
The converted app can still access file system and registry. There are some redirections involved. For details of the how DAC handle this, check Behind the scenes of the Desktop Bridge.
App packages contain a registry.dat file, which serves as the logical equivalent of HKLM\Software in the real registry...