How to implement properly plugins in C#?

I'm trying to add plugins to my game and what I'm trying to implement is this:

Plugins will be either mine or 3rd party's so I would like a solution where crashing of the plugin would not mean crashing of the main application.
Methods of plugins are called very often (for example because of drawing of game objects).

What I've found so far:

1) http://www.codeproject.com/KB/cs/pluginsincsharp.aspx - simple concept that seems like it should work nicely. Since plugins are used in my game for every round I would suffice to add the Restart() method and if a plugin is no longer needed Unload() method + GC should take care of that.
2) http://mef.codeplex.com/Wikipage - Managed Extensibility Framework - my program should work on .NET 3.5 and I don't want to add any other framework separately I want to write my plugin system myself. Therefore this solution is out of question.
3) Microsoft provides: http://msdn.microsoft.com/en-us/library/system.addin.aspx but according to a few articles I've read it is very complex.
4) Different AppDomains for plugins. According to Marc Gravell ( Usage of AppDomain in C# ) different AppDomains allow isolation. Unloading of plugins would be easy. What would the performance load be? I need to call methods of plugins very often (to draw objects for example).
- Using Application Domains - http://msdn.microsoft.com/en-us/library/yb506139.aspx
- c# plugins

Edit Report

1 Answer

I used this tutorial as the basis for my own plug-in architecture a couple of years ago. My architecture was, I believe, a relatively simple architecture, but I hit some problems when it came to passing messages between plug-ins.

If you're intent on writing your own architecture, then fair enough, but I would warn against it. It's no small undertaking, and sooner or later you're going to run into some major design considerations, like message passing, which are non-trivial to solve (if admittedly simultaneously quite interesting and frustrating). There is a tremendous amount of value in using something like MEF that solves these problems for you, and provides a really nice API and framework upon which you can build you plug-ins.

Furthermore, MEF will end up being distributed as part of your application, so you don't need to get your users to download it separately; it's an "invisible" dependency as far as they're concerned, and a light-weight one for developers, including yourself. It's also the official plug-in architecture for Visual Studio 2010, so it has a lot of weight in the .NET community, and there will only ever be more developers able to write plug-ins for your app if you use it too.

Hope that makes some sense.

answered 2010-04-15T09:47:00.007

How to implement properly plugins in C#?

1 Answer

Your Answer