Loading DLL into separate AppDomain

Question

I am writing a plugin architecture. My plugin dlls are located in a sub directory from where the plugin manager is running. I am loading the plugins into a separate AppDomain as the following:

string subDir;//initialized to the path of the module's directory.
AppDomainSetup setup = new AppDomainSetup();
setup.PrivateBinPath = subDir;
setup.ApplicationBase = subDir;

AppDomain newDomain= AppDomain.CreateDomain(subDir, null, setup);

byte[] file = File.ReadAllBytes(dllPath);//dll path is a dll inside subDir
newDomain.Load(file);

However. newDomain.Load returns an assembly which the currently domain attempts to load. Because the plugin dlls are in a sub directory, the current domain cannot and should not see these dlls and the current domain throws a FileLoadException "ex = {"Could not load file or assembly ... or one of its dependencies."

The question is, can we load an assembly into a separate AppDomain without it returning the loaded assembly?

I know I can add a handler for the AssemblyResolve event in the current domain and return a null, but I would prefer to not to go this route.

Thanks in advance.

Look at this one : stackoverflow.com/questions/2715104/… and this one: stackoverflow.com/questions/2132649/… — decyclone
If you're building a plugin architecture, maybe this article would be useful: msdn.microsoft.com/en-us/magazine/cc163476.aspx — Simon Mourier

Aerik Aerik · Accepted Answer · 2012-01-27T00:16:03

You can also use DoCallBack - here's something I put together after reading lots about it on SO. This creates an appdomain, checks that the assemblies have the same signature public key, loads the assembly, executes a static method, unloads the appdomain, then deletes the dll.

static void Main(string[] args)
    {
        string unknownAppPath = @"path-to-your-dll";

        Console.WriteLine("Testing");
        try
        {
            AppDomainSetup setup = new AppDomainSetup();
            setup.AppDomainInitializer = new AppDomainInitializer(TestAppDomain);
            setup.AppDomainInitializerArguments = new string[] { unknownAppPath };
            AppDomain testDomain = AppDomain.CreateDomain("test", AppDomain.CurrentDomain.Evidence, setup);
            AppDomain.Unload(testDomain);
            File.Delete(unknownAppPath);
        }
        catch (Exception x)
        {
            Console.WriteLine(x.Message);
        }
        Console.ReadKey(); 
    }

    public static void TestAppDomain(string[] args)
    {
        string unknownAppPath = args[0];
        AppDomain.CurrentDomain.DoCallBack(delegate()
        {
            //check that the new assembly is signed with the same public key
            Assembly unknownAsm = AppDomain.CurrentDomain.Load(AssemblyName.GetAssemblyName(unknownAppPath));
            //get the new assembly public key
            byte[] unknownKeyBytes = unknownAsm.GetName().GetPublicKey();
            string unknownKeyStr = BitConverter.ToString(unknownKeyBytes);
            //get the current public key
            Assembly asm = Assembly.GetExecutingAssembly();
            AssemblyName aname = asm.GetName();
            byte[] pubKey = aname.GetPublicKey();
            string hexKeyStr = BitConverter.ToString(pubKey);
            if (hexKeyStr == unknownKeyStr)
            {
                //keys match so execute a method
                Type classType = unknownAsm.GetType("namespace.classname");
                classType.InvokeMember("method-you-want-to-invoke", BindingFlags.InvokeMethod, null, null, null);
            }
        });
    }

Loading DLL into separate AppDomain

2 Answers