Search code examples
c#.netsessiondynamicmodular

Modular System in .NET Able to be Altered at Runtime

Currently I'm working on a .NET hobby project that involves a complex system of objects which work in combination with eachother. However, I encountered a little problem, I am unable to find a mechanism in .NET to support replacing code at runtime, and be able to dispose of the old code, loaded previously. This means replacing a module/object dynamically and almost instantly displaying the changes to the user, for example, when he restarts a procedure, but not the whole program.

I have already taken into account the possibility of having separate AppDomain for each session and loading the necessary assemblies into it but this seems a little bit too expensive. I should also mention that every session benefits from a common base of assemblies, for instance, to connect to a database, so this means loading those classes into every single session. Marshalling data back and forth from the separate AppDomain also represents an additional overhead (could be used when data is sent to the client application through the network, code for this contained in the main AppDomain, which manages the sessions).

Is there a framework or way of replacing/unloading particular parts of code? How is it done in real-world applications? Can there be a workaround? Or have I picked the wrong set of tools?

Solution

  • You need some kind of plugin system with well defined interfaces. Then you load at runtime binaries (your plugin *.dll) and create objects from it and then execute methods on it. When you create a system where objects from your plugins must be created through your IPluginManager you have no problem with replacing code at runtime. :)

    Or

    You have something like a folder with *.cs files which will on demand compiled (in memory) and create the objects you want to use from them and call the methods on them. Which is basically the same like above, without compiling at run time.

    From there you can make further improvements.

    EDIT: Like you wrote the only problem without using AppDomain is that once loaded assemblies can't be unloaded. But that's not really a problem.