Question

Edit: I would like to keep the infrastructure as is, so while the framework ideas are appreciated, please keep your suggestions centered on the context I have provided.

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Background

I’m building a web-based application that dynamically loads plugins. Each plugin comes with a manifest file that contains its dll location, namespace, and type.

Right now I’m using System.Reflection.Assembly.LoadFile to load up the dlls based off the locations provided in the manifest files. Then I load the types and so on.

As an Aside:
I may wind up changing to System.Reflection.Assembly.LoadFrom since I’ll eventually be loading files from outside the bin directory. But if their is a better way (Assembly.Load or something), feel free to add that in as well

Problem

The problem is that Multiple plugins can potentially run off the same dll. So I wind up executing System.Reflection.Assembly.LoadFile("Identical.dll") multiple times.

I have the idea to check if my assembly has already been loaded by iterating through AppDomain.CurrentDomain.GetAssemblies(), but I don’t know if that will help with performance (or if it will work period, I haven’t tried it).

Also, I can’t keep a list of loaded assemblies due to the project’s design constraints (though you may argue that it’s a poor design: I can’t change it, even if I wanted to OR agreed with you… so please don’t press the issue……. please….. unless you really feel that strongly about it, I guess you can add that in as a suggestion).

Ultimately my goals are:

1. Don’t ever re-load the same assembly twice.
2. Performance is key.

Answer 1

If you use LoadFrom for all of your calls, it will only load the assembly once per AppDomain. See the MSDN topic and Suzanne Cook’s Choosing a Binding Context for more details.