动态切换配置文件（Web或app config）

Question

I have a web application that refers to a DLL. This DLL has certain config values, which are normally part of the web.config.

There is a requirement to invoke this DLL under different configurations, from the web application. The DLL is third-party and cannot be changed.

Have tried the below and failed.

1. Have different copies of DLL (named a.dll, b.dll) and load it by reflection. The problem here is that it'll still look for the web.config and not the a.dll.config. Also, since same Types are referenced in the main program as well as the reflected assembly, it goes crazy.
2. Change the config on the fly using AppDomain.CurrentDomain.SetData("WEB_CONFIG_FILE", @"Config\\Path") and switch it back after the call. The problem here is that after the first time, it doesn't load the config section again even if I switch.
3. Use ConfigurationManager.RefreshSection(@"configuration\\mysection") to force a refresh. This doesn't seem to work and people say this call is buggy in .NET
4. I've seen some recommendation to update the web.config, but this may not be a good choice for me because the switching of values would happen fairly frequently

Is there anything else I can do?

Answer 1

Host the DLL in a separate process and communicate using COM (or .Net remoting or a web service or similar).

Ie create a host process a.exe using C# (say) which exposes classes as COM objects, the classes in turn calling the DLL methods/classes. Register as COM objects.

Then create b.exe the same (but with different CLSIDs).

You can now have different configuration files for a.exe and b.exe (in different folders), yet both can use the DLL services.

You could also do something similar by having two internal web apps and using SOAP or something to talk to them.

But the bottom line is if the DLL works on web.config, you have to put at least one of them into a separate process in a separate folder.