Re: Calling host AppDomain from new AppDomain

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okaminer wrote:
I've tried what you've suggested
I've passed a delegate to the function but when i call that delegate
the function runs under the second Domain (new domain) and not the
host domain
This is the code

//Call back delegate
public delegate void CallBackDelegate(string str);
//Proxy class
public class ProxyClass:MarshalByRefObject
{
public void DoSomething(string str, CallBackDelegate callback)
{

System.Diagnostics.Debug.WriteLine(str + " from domain " +
AppDomain.CurrentDomain.Id);
//This function is called in the new AppDomain
callback("My Value");

You don't show the code that passes "callback", but whatever object the delegate is referring to must be a MarshalByRefObject created in the first AppDomain for the execution context to change. If it's serializable, the object will just be copied over to the new domain. Here's a complete sample:

class NewDomainObject : MarshalByRefObject {
public void DoCallback(Action callback) {
Console.WriteLine("NewDomainObject executing in domain " + AppDomain.CurrentDomain.FriendlyName);
callback();
}
}

class OldDomainObject : MarshalByRefObject {
public void PrintDomain() {
Console.WriteLine("OldDomainObject executing in domain " + AppDomain.CurrentDomain.FriendlyName);
}
}

class Program {
static void Main(string[] args) {
var newDomain = AppDomain.CreateDomain("New domain");
var oldDomainObject = new OldDomainObject();
var newDomainObject = (NewDomainObject) newDomain.CreateInstanceAndUnwrap(Assembly.GetExecutingAssembly().FullName, typeof(NewDomainObject).FullName);
newDomainObject.DoCallback(oldDomainObject.PrintDomain);
}
}

If you just need an isolated piece of code to execute in another AppDomain, you can also consider using AppDomain.DoCallBack(), but this approach is simpler.

--
J.
.

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