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ObjectHandle Class

Wraps marshal by value object references, allowing them to be returned through an indirection.

For a list of all members of this type, see ObjectHandle Members.

System.Object
   System.MarshalByRefObject
      System.Runtime.Remoting.ObjectHandle

[Visual Basic]
<ClassInterface(ClassInterfaceType.AutoDual)>
Public Class ObjectHandle
   Inherits MarshalByRefObject
   Implements IObjectHandle
[C#]
[ClassInterface(ClassInterfaceType.AutoDual)]
public class ObjectHandle : MarshalByRefObject, IObjectHandle
[C++]
[ClassInterface(ClassInterfaceType::AutoDual)]
public __gc class ObjectHandle : public MarshalByRefObject,
   IObjectHandle
[JScript]
public
   ClassInterface(ClassInterfaceType.AutoDual)
class ObjectHandle extends MarshalByRefObject implements
   IObjectHandle

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

The ObjectHandle class is used to pass an object (in a wrapped state) between multiple application domains without loading the metadata for the wrapped object in each AppDomain through which the ObjectHandle travels. Thus, the ObjectHandle class gives the caller control of when the Type of the remote object is loaded into a domain.

Example

[Visual Basic, C#, C++] The following code example shows how to create an object in another AppDomain, and retrieve a proxy to the object from an ObjectHandle. In this example, you can assume that the code of the MyType class is compiled into an assembly called "ObjectHandleAssembly".

[Visual Basic] 
Imports System
Imports System.Runtime.Remoting


Public Class MyType
   Inherits MarshalByRefObject
      
   Public Sub New()
      Console.Write("Created an instance of MyType in an AppDomain with the ")
      Console.WriteLine("hashcode {0}", AppDomain.CurrentDomain.GetHashCode())
      Console.WriteLine("")
   End Sub 'New
   
   
   Public Function GetAppDomainHashCode() As Integer
      Return AppDomain.CurrentDomain.GetHashCode()
   End Function 'GetAppDomainHashCode

End Class 'MyType


Class Test
     
   Public Shared Sub Main()
      
      Console.WriteLine("The hash code of the default AppDomain is {0}.", AppDomain.CurrentDomain.GetHashCode())
      Console.WriteLine("")
      
      ' Creates another AppDomain.
      Dim domain As AppDomain = AppDomain.CreateDomain("AnotherDomain", Nothing, CType(Nothing, AppDomainSetup))
      
      ' Creates an instance of MyType defined in the assembly called ObjectHandleAssembly.
      Dim obj As ObjectHandle = domain.CreateInstance("ObjectHandleAssembly", "MyType")
      
      ' Unwrapps the proxy to the MyType object created in the other AppDomain.
      Dim testObj As MyType = CType(obj.Unwrap(), MyType)
      
      If RemotingServices.IsTransparentProxy(testObj) Then
         Console.WriteLine("The unwrapped object is a proxy.")
      Else
         Console.WriteLine("The unwrapped object is not a proxy!")
      End If 
      Console.WriteLine("")
      Console.Write("Calling a method on the object located in an AppDomain with the hash code ")
      Console.WriteLine(testObj.GetAppDomainHashCode())

   End Sub 'Main 

End Class 'Test 

[C#] 
using System;
using System.Runtime.Remoting;


public class MyType : MarshalByRefObject {

   public MyType()  {
      Console.Write("Created an instance of MyType in an AppDomain with the ");
      Console.WriteLine("hash code {0}",AppDomain.CurrentDomain.GetHashCode());
      Console.WriteLine("");
   }

   public int GetAppDomainHashCode() {
      return AppDomain.CurrentDomain.GetHashCode();
   }
}


class Test {

   public static void Main() {

      Console.WriteLine("The hash code of the default AppDomain is {0}.", 
                        AppDomain.CurrentDomain.GetHashCode());
      Console.WriteLine("");

      // Creates another AppDomain.
      AppDomain domain = AppDomain.CreateDomain("AnotherDomain", 
                                                null, 
                                                (AppDomainSetup)null);

      // Creates an instance of MyType defined in the assembly called ObjectHandleAssembly.
      ObjectHandle obj = domain.CreateInstance("ObjectHandleAssembly", "MyType");

      // Unwrapps the proxy to the MyType object created in the other AppDomain.
      MyType testObj = (MyType)obj.Unwrap();

      if(RemotingServices.IsTransparentProxy(testObj))
         Console.WriteLine("The unwrapped object is a proxy.");
      else
         Console.WriteLine("The unwrapped object is not a proxy!");    

      Console.WriteLine("");
      Console.Write("Calling a method on the object located in an AppDomain with the hash code ");
      Console.WriteLine(testObj.GetAppDomainHashCode());
   }
}

[C++] 
#using <mscorlib.dll>

using namespace System;
using namespace System::Runtime::Remoting;


public __gc class MyType : public MarshalByRefObject {

public:
   MyType() {
      Console::Write(S"Created an instance of MyType in an AppDomain with the ");
      Console::WriteLine(S"hash code {0}", __box( AppDomain::CurrentDomain->GetHashCode()));
      Console::WriteLine(S"");
   }

public:
   int GetAppDomainHashCode() {
      return AppDomain::CurrentDomain->GetHashCode();
   }
};



int main() {

   Console::WriteLine(S"The hash code of the default AppDomain is {0}.",
      __box(                        AppDomain::CurrentDomain->GetHashCode()));
   Console::WriteLine(S"");

   // Creates another AppDomain.
   AppDomain*  domain = AppDomain::CreateDomain(S"AnotherDomain",
      0,
      (AppDomainSetup*)0);

   // Creates an instance of MyType defined in the assembly called ObjectHandleAssembly.
   ObjectHandle*  obj = domain->CreateInstance(S"ObjectHandleAssembly", S"MyType");

   // Unwraps the proxy to the MyType object created in the other AppDomain.
   MyType* testObj = dynamic_cast<MyType*>(obj->Unwrap());

   if (RemotingServices::IsTransparentProxy(testObj))
      Console::WriteLine(S"The unwrapped object is a proxy.");
   else
      Console::WriteLine(S"The unwrapped object is not a proxy!");

   Console::WriteLine(S"");
   Console::Write(S"Calling a method on the object located in an AppDomain with the hash code ");
   Console::WriteLine(testObj->GetAppDomainHashCode());
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Runtime.Remoting

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: Mscorlib (in Mscorlib.dll)

See Also

ObjectHandle Members | System.Runtime.Remoting Namespace

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