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MarshalByRefObject Class

Enables access to objects across application domain boundaries in applications that support remoting.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class MarshalByRefObject

An application domain is a partition in an operating system process where one or more applications reside. Objects in the same application domain communicate directly. Objects in different application domains communicate either by transporting copies of objects across application domain boundaries, or by using a proxy to exchange messages.

MarshalByRefObject is the base class for objects that communicate across application domain boundaries by exchanging messages using a proxy. Objects that do not inherit from MarshalByRefObject are implicitly marshal by value. When a remote application references a marshal by value object, a copy of the object is passed across application domain boundaries.

MarshalByRefObject objects are accessed directly within the boundaries of the local application domain. The first time an application in a remote application domain accesses a MarshalByRefObject, a proxy is passed to the remote application. Subsequent calls on the proxy are marshaled back to the object residing in the local application domain.

Types must inherit from MarshalByRefObject when the type is used across application domain boundaries, and the state of the object must not be copied because the members of the object are not usable outside the application domain where they were created.

This section contains two code examples. The first code example shows how to create an instance of a class in another application domain. The second code example shows a simple class that can be used for remoting.

Example 1

The following code example shows the simplest way to execute code in another application domain. The example defines a class named Worker that inherits MarshalByRefObject, with a method that displays the name of the application domain in which it is executing. The example creates instances of Worker in the default application domain and in a new application domain.

NoteNote:

The assembly that contains Worker must be loaded into both application domains, but it could load other assemblies that would exist only in the new application domain.

using System;
using System.Reflection;

public class Worker : MarshalByRefObject
{
    public void PrintDomain() 
    { 
        Console.WriteLine("Object is executing in AppDomain \"{0}\"",
            AppDomain.CurrentDomain.FriendlyName); 
    }
}

class Example
{
    public static void Main()
    {
        // Create an ordinary instance in the current AppDomain
        Worker localWorker = new Worker();
        localWorker.PrintDomain();

        // Create a new application domain, create an instance 
        // of Worker in the application domain, and execute code 
        // there.
        AppDomain ad = AppDomain.CreateDomain("New domain");
        Worker remoteWorker = (Worker) ad.CreateInstanceAndUnwrap(
            Assembly.GetExecutingAssembly().FullName,
            "Worker");
        remoteWorker.PrintDomain();
    }
}

/* This code produces output similar to the following:

Object is executing in AppDomain "source.exe"
Object is executing in AppDomain "New domain"
 */

Example 2

The following example demonstrates a class derived from MarshalByRefObject that is used later in remoting.

using System;
using System.Runtime.Remoting;
using System.Security.Permissions;

public class SetObjectUriForMarshalTest  {

    class TestClass : MarshalByRefObject {
    }

    [SecurityPermission(SecurityAction.Demand, Flags=SecurityPermissionFlag.RemotingConfiguration)] 
    public static void Main()  {

        TestClass obj = new TestClass();    

        RemotingServices.SetObjectUriForMarshal(obj, "testUri");
        RemotingServices.Marshal(obj);

        Console.WriteLine(RemotingServices.GetObjectUri(obj));
    }
}
System.Object
  System.MarshalByRefObject
    IEHost.Execute.IEExecuteRemote
    Microsoft.Build.Utilities.AppDomainIsolatedTask
    Microsoft.Build.Utilities.TaskItem
    Microsoft.Build.Utilities.TaskLoggingHelper
    Microsoft.ManagementConsole.Internal.Request
    Microsoft.Win32.RegistryKey
    System.AddIn.Pipeline.ContractBase
    System.AppDomain
    System.AppDomainManager
    System.ComponentModel.Component
    System.ContextBoundObject
    System.Data.Common.DataColumnMapping
    System.Data.Common.DataColumnMappingCollection
    System.Data.Common.DataTableMapping
    System.Data.Common.DataTableMappingCollection
    System.Data.Common.DbDataReader
    System.Data.Common.DbParameter
    System.Data.Common.DbParameterCollection
    System.Data.Common.DbTransaction
    System.Diagnostics.TraceListener
    System.DirectoryServices.SearchResultCollection
    System.Drawing.Brush
    System.Drawing.Drawing2D.CustomLineCap
    System.Drawing.Drawing2D.GraphicsContainer
    System.Drawing.Drawing2D.GraphicsPath
    System.Drawing.Drawing2D.GraphicsPathIterator
    System.Drawing.Drawing2D.GraphicsState
    System.Drawing.Drawing2D.Matrix
    System.Drawing.Font
    System.Drawing.FontFamily
    System.Drawing.Graphics
    System.Drawing.Icon
    System.Drawing.Image
    System.Drawing.Pen
    System.Drawing.Region
    System.Drawing.StringFormat
    System.EnterpriseServices.Internal.AssemblyLocator
    System.EnterpriseServices.RegistrationHelper
    System.IO.FileSystemInfo
    System.IO.IsolatedStorage.IsolatedStorage
    System.IO.Stream
    System.IO.TextReader
    System.IO.TextWriter
    System.Messaging.MessageEnumerator
    System.Messaging.MessageQueueEnumerator
    System.Net.WebRequest
    System.Net.WebResponse
    System.Reflection.AssemblyNameProxy
    System.Runtime.InteropServices.StandardOleMarshalObject
    System.Runtime.Remoting.Lifetime.ClientSponsor
    System.Runtime.Remoting.ObjectHandle
    System.Speech.Recognition.SrgsGrammar.SrgsElement
    System.Threading.RegisteredWaitHandle
    System.Threading.Timer
    System.Threading.WaitHandle
    System.Web.Compilation.ClientBuildManager
    System.Web.Compilation.ClientBuildManagerCallback
    System.Web.Hosting.ApplicationManager
    System.Web.Hosting.HostingEnvironment
    System.Web.Hosting.ISAPIRuntime
    System.Web.Hosting.VirtualFileBase
    System.Web.Hosting.VirtualPathProvider
    System.Windows.Forms.BaseCollection
    System.Windows.Forms.NativeWindow
    System.Windows.Forms.NumericUpDownAccelerationCollection
    System.Windows.Forms.OwnerDrawPropertyBag
    System.Windows.Forms.TreeNode
    System.Windows.Interop.DocObjHost
    System.Workflow.Runtime.DebugEngine.DebugController
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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