System.InvalidCastException: 'Unable to cast transparent proxy to type 'newdomaintest0912.Animal'.' when pass an object from default appdomain to child appdomain

Question

I create a child domain, if I set ApplicationBase as the other directory which is not the same as the main application , I create an object which is inherit from MarshalByRefObject in default domain then transmit it to child domain, child domain cannot cast it as actual type, it throw System.InvalidCastException: 'Unable to cast transparent proxy to type 'newdomaintest0912.Animal'.' exception, but if I set ApplicationBase as AppDomain.CurrentDomain.BaseDirectory, the problem will go away.

I need to set it as a different directory, is there a way to implement it.

below is the code.

class Program
    {
        static void Main(string[] args)
        {

            var adl = new ScriptDynamicLoader();

            var _ = new Animal();
            _.Name = "Cat";
            _.Ege = 2;
            var hand = new System.Runtime.Remoting.ObjectHandle(_);
            adl.remoteLoader.printObject(new System.Runtime.Remoting.ObjectHandle(_));

        }
    }

namespace newdomaintest0912
{
    public class ScriptDynamicLoader
    {
        private AppDomain appDomain;

        public readonly RemoteLoader remoteLoader;
        public ScriptDynamicLoader()
        {
            AppDomainSetup setup = new AppDomainSetup();
            setup.ApplicationBase = @"C:\Users\zjiae07737\source\repos\Scripting20Spike\Script2\bin\Debug";
            //setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory;

            appDomain = AppDomain.CreateDomain("ScriptDomain", null, setup);
            remoteLoader = appDomain.CreateInstanceFromAndUnwrap(typeof(RemoteLoader).Assembly.Location, typeof(RemoteLoader).FullName) as RemoteLoader;

        }
    }

    public class RemoteLoader : MarshalByRefObject
    {
        public ObjectHandle getObject()
        {
            var _ = new Animal();
            _.Name = "Dog";
            _.Ege = 10;
            Console.WriteLine(AppDomain.CurrentDomain.Id);
            return new ObjectHandle(_);
        }

        public void printObject (ObjectHandle objectHandle)
        {
            var wrap = objectHandle.Unwrap();
            var ami = (Animal)wrap;

            ami.print();
        }
    }


    public class Animal : MarshalByRefObject
    {
        public string Name;
        public int Ege;


        public void print()
        {
            Console.WriteLine($"The name is {Name}, the age is {Ege}. The domain id is {AppDomain.CurrentDomain.Id}.");
        }

    }
}

Answer 1

Hi @Jiang, Zhiyou , Welcome to Microsoft Q&A,

In code, when you set a different directory as a subdirectory, the .NET runtime treats the child class as a different type than the class in the parent class, even though they have the same name and namespace.

Do you mean this?

using System;

namespace _9_13_x
{
    internal class Program
    {
        static void Main(string[] args)
        {
            var adl = new ScriptDynamicLoader();

            // Use IAnimal interface instead of Animal.
            var animal = adl.remoteLoader.getObject();
            adl.remoteLoader.printObject(animal);
            Console.ReadLine();
        }
    }

    public class ScriptDynamicLoader
    {
        private AppDomain appDomain;

        public readonly RemoteLoader remoteLoader;
        public ScriptDynamicLoader()
        {
            AppDomainSetup setup = new AppDomainSetup();
            setup.ApplicationBase = @"C:\Users\Administrator\Desktop\";
            appDomain = AppDomain.CreateDomain("ScriptDomain", null, setup);
            remoteLoader = appDomain.CreateInstanceFromAndUnwrap(typeof(RemoteLoader).Assembly.Location, typeof(RemoteLoader).FullName) as RemoteLoader;
        }
    }

    public class RemoteLoader : MarshalByRefObject
    {
        public IAnimal getObject()
        {
            var animal = new Animal();
            animal.Name = "Dog";
            animal.Ege = 10;
            Console.WriteLine(AppDomain.CurrentDomain.Id);
            return animal;
        }

        public void printObject(IAnimal animal)
        {
            animal.print();
        }
    }

    // Define a shared interface without MarshalByRefObject.
    public interface IAnimal
    {
        void print();
    }

    // Modify the Animal class to inherit from MarshalByRefObject and implement the shared interface.
    public class Animal : MarshalByRefObject, IAnimal
    {
        public string Name;
        public int Ege;

        public void print()
        {
            Console.WriteLine($"The name is {Name}, the age is {Ege}. The domain id is {AppDomain.CurrentDomain.Id}.");
        }
    }
}

Best Regards,

Jiale

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