Question

if i use

Assembly assembly = Assembly.LoadFrom(file);

and later try to use the file , i get an exception stating that the file is in use .

i need to load it on to a new appdomain .

all i seem to find is examples of how to create an instance with in the Assembly ,
is there a way to load the entire assembly.

what i need is to :

 (1) load the assembly into a new AppDomain from a file . 
 (2) extract an embedded  resource (xml file) from the Dll .
 (3) extract a type of class which implements an interface (which i know the interface type) .
 (4) unload the entire appdomain in order to free the file .  

2-4 is not a problem

i just can’t seem to find how to load the Assembly into a new AppDomin , only examples of
create instance , which gives me an instace of the class from with in the Dll .

i need the entire thing.

like in this question : another example of Create instance .

Loading DLLs into a separate AppDomain

Answer 1

The most basic multidomain scenario is

static void Main()
{
    AppDomain newDomain = AppDomain.CreateDomain("New Domain");
    newDomain.ExecuteAssembly("file.exe");
    AppDomain.Unload(newDomain);
}

Calling ExecuteAssembly on a seperate domain is convienient but does not offer the ability to interact with the domain itself. It also requires the target assembly to be an executable and forces the caller to a single entry point. To incorporate some flexibility you could also pass a string or args to the .exe.

I hope this helps.

Extension: Try something like the following then

AppDomainSetup setup = new AppDomainSetup();
setup.AppDomainInitializer = new AppDomainInitializer(ConfigureAppDomain);
setup.AppDomainInitializerArguments = new string[] { unknownAppPath };
AppDomain testDomain = AppDomain.CreateDomain("test", AppDomain.CurrentDomain.Evidence, setup);
AppDomain.Unload(testDomain);
File.Delete(unknownAppPath);

where the AppDomain can be initilised as follows

public static void ConfigureAppDomain(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("MethodNameToInvoke", BindingFlags.InvokeMethod, null, null, null);
        }
    });
}