MarshalByRefObject Class
Assembly: mscorlib (in mscorlib.dll)
'Declaration <SerializableAttribute> _ <ComVisibleAttribute(True)> _ Public MustInherit Class MarshalByRefObject 'Usage Dim instance As MarshalByRefObject
/** @attribute SerializableAttribute() */ /** @attribute ComVisibleAttribute(true) */ public abstract class MarshalByRefObject
SerializableAttribute ComVisibleAttribute(true) public abstract class MarshalByRefObject
Not applicable.
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.
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| 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. |
Imports System Imports System.Reflection Public Class Worker Inherits MarshalByRefObject Public Sub PrintDomain() Console.WriteLine("Object is executing in AppDomain ""{0}""", _ AppDomain.CurrentDomain.FriendlyName) End Sub End Class Class Example Public Shared Sub Main() ' Create an ordinary instance in the current AppDomain Dim localWorker As New Worker() localWorker.PrintDomain() ' Create a new application domain, create an instance ' of Worker in the application domain, and execute code ' there. Dim ad As AppDomain = AppDomain.CreateDomain("New domain") Dim remoteWorker As Worker = CType( _ ad.CreateInstanceAndUnwrap( _ [Assembly].GetExecutingAssembly().FullName, _ "Worker"), _ Worker) remoteWorker.PrintDomain() End Sub End Class ' 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.
Imports System Imports System.Runtime.Remoting Imports System.Security.Permissions Public Class SetObjectUriForMarshalTest Class TestClass Inherits MarshalByRefObject End Class <SecurityPermission(SecurityAction.LinkDemand)> _ Public Shared Sub Main() Dim obj As TestClass = New TestClass() RemotingServices.SetObjectUriForMarshal(obj, "testUri") RemotingServices.Marshal(obj) Console.WriteLine(RemotingServices.GetObjectUri(obj)) End Sub End Class
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.
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