ApplicationActivator Class

Note: This class is new in the .NET Framework version 2.0.

Provides the base class for the activation of manifest-based assemblies.

Namespace: System.Runtime.Hosting
Assembly: mscorlib (in mscorlib.dll)

public class ApplicationActivator
/** @attribute ComVisibleAttribute(true) */ 
public class ApplicationActivator
public class ApplicationActivator

There is a single designated instance of the ApplicationActivator class in each AppDomain to which all activation calls are routed. The AppDomainManager for the current AppDomain can provide its own custom ApplicationActivator for this purpose. If a custom ApplicationActivator is not provided, an instance of the default ApplicationActivator is created.

The following steps describe the behavior of the default CreateInstance method implementation:

  1. Checks if the ActivationContext of the add-in to be activated matches the ActivationContext of the current domain; if not, proceeds to step 2. Otherwise, executes the assembly and returns the result wrapped in an object handle.

  2. Activates the add-in in a new AppDomain. The following steps are taken to initialize a new AppDomain using the ActivationArguments for the add-in.

    1. Creates a new AppDomainSetup object using an ActivationArguments object containing the activation context for the add-in.

    2. Calls the CreateInstanceHelper method to create a new domain using the AppDomainSetup object.

    3. The CreateInstanceHelper method calls the HostSecurityManager.DetermineApplicationTrust method to acquire an ApplicationTrust object for the add-in. If the IsApplicationTrustedToRun property returns true, the add-in is executed. If not, CreateInstanceHelper throws a PolicyException indicating that execution permission could not be acquired.

    4. If the add-in is trusted to run, then a new AppDomain is created and configured for the ActivationContext of the add-in, and the add-in is loaded and executed.

    5. The result of the activation of the add-in is returned, wrapped in an object handle.

A custom activator can tailor the activation of an add-in to a particular set of circumstances. For example, a custom activator could find an existing AppDomain to activate this add-in instead of creating a new domain every time.

The following steps describe the behavior of a custom ApplicationActivator that activates an add-in in an existing AppDomain:

  1. The custom activator finds a domain that has the same ActivationContext as the add-in that is being activated.

  2. If the ActivationContext has never been seen before in the process, the custom activator creates a new AppDomain for this ActivationContext by calling the CreateDomain method directly, or delegating this activity to the CreateInstanceHelper in the base class.

  3. If there is an existing domain with the same ActivationContext, then the activator can delegate the CreateInstance method call to the ApplicationActivator in the target domain. Note that this would be a cross-domain call to an ApplicationActivator that resides in the target AppDomain.

The following code example shows how to obtain an ApplicationActivator object from the current DomainManager for a manifest-based application.

using System;
using System.Collections;
using System.Text;
using System.Security.Policy;
using System.Reflection;
using System.Security;
using System.Security.Permissions;
using System.Runtime.Hosting;

namespace ActivationContextSample
    public class Program : MarshalByRefObject
        [SecurityPermission(SecurityAction.LinkDemand, ControlDomainPolicy=true)]
        public static void Main(string[] args)
            // Get the AppDomainManager from the current domain.
            AppDomainManager domainMgr = AppDomain.CurrentDomain.DomainManager;
            // Get the ApplicationActivator from the AppDomainManager.
            ApplicationActivator appActivator = domainMgr.ApplicationActivator;
            Console.WriteLine("Assembly qualified name from the application activator.");
            // Get the ActivationArguments from the SetupInformation property of the domain.
            ActivationArguments activationArgs = AppDomain.CurrentDomain.SetupInformation.ActivationArguments;
            // Get the ActivationContext from the ActivationArguments.
            ActivationContext actContext = activationArgs.ActivationContext;
            Console.WriteLine("The ActivationContext.Form property value is: " +
	[SecurityPermission(SecurityAction.LinkDemand, ControlDomainPolicy=true)]
        public void Run()
            Main(new string[] { });


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 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0

Community Additions