Load ASP.NET Web API plugin assemblies in separate AppDomain

Question

I'm creating a CMS-like application under MVC.

To handle backend code for plugins I use Web API, so putting my API DLLs in /bin folder enables me to access plugin service methods by a specific route - /api/{namespace}/{controller}/{id}.

I would like to load the assemblies from another location, then be able to unload them in case of new module install/upgrade/delete.

People suggest to override the DefaultAssembliesResolver to include plugin assemblies:

public class PluginAssembliesResolver : DefaultAssembliesResolver
{
    public override ICollection<Assembly> GetAssemblies()
    {
        List<Assembly> assemblies = new List<Assembly>(base.GetAssemblies());

        foreach (string assemblyPath in ModuleManager.GetAllAssemblyPaths(HttpContext.Current.Server))
        {
            if (File.Exists(assemblyPath))
            {
                assemblies.Add(Assembly.LoadFrom(assemblyPath));
            }
        }

        return assemblies;
    }
}

But in this case I am loading the assemblies into the current domain and I am not able to unload them.

Trying to load assemblies from another location throws an error (it recognizes my assembly, but tries to look for the same DLL under /bin or /bin/myPlugin folders):

AppDomain domain = AppDomain.CreateDomain("myDomain", null);     

Assembly assembly = Assembly.LoadFrom(@"C:\myPluginPath\myPlugin.dll");

domain.Load(assembly.GetName());

How can I load them into a separate AppDomain?

Thank you.

Nick Nick · Accepted Answer · 2016-11-25T13:30:43

You need to overwrite the DefaultHttpControllerSelector. Here is a very nice article on the subject: link Hope this helps

Load ASP.NET Web API plugin assemblies in separate AppDomain

2 Answers