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AppDomain Class

Definition

Represents an application domain, which is an isolated environment where applications execute. This class cannot be inherited.

public sealed class AppDomain : MarshalByRefObject
public class AppDomain : MarshalByRefObject
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
public sealed class AppDomain : MarshalByRefObject, _AppDomain, System.Security.IEvidenceFactory
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class AppDomain : MarshalByRefObject, _AppDomain, System.Security.IEvidenceFactory
Inheritance
Attributes
Implements

Examples

This example shows how to create a new AppDomain, instantiate a type in that new AppDomain, and communicate with that type's object. In addition, this example shows how to unload the AppDomain causing the object to be garbage collected.

using System;
using System.Reflection;
using System.Threading;

class Module1
{
    public static void Main()
    {
        // Get and display the friendly name of the default AppDomain.
        string callingDomainName = Thread.GetDomain().FriendlyName;
        Console.WriteLine(callingDomainName);

        // Get and display the full name of the EXE assembly.
        string exeAssembly = Assembly.GetEntryAssembly().FullName;
        Console.WriteLine(exeAssembly);

        // Construct and initialize settings for a second AppDomain.
        AppDomainSetup ads = new AppDomainSetup();
        ads.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory;

        ads.DisallowBindingRedirects = false;
        ads.DisallowCodeDownload = true;
        ads.ConfigurationFile =
            AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;

        // Create the second AppDomain.
        AppDomain ad2 = AppDomain.CreateDomain("AD #2", null, ads);

        // Create an instance of MarshalbyRefType in the second AppDomain.
        // A proxy to the object is returned.
        MarshalByRefType mbrt =
            (MarshalByRefType) ad2.CreateInstanceAndUnwrap(
                exeAssembly,
                typeof(MarshalByRefType).FullName
            );

        // Call a method on the object via the proxy, passing the
        // default AppDomain's friendly name in as a parameter.
        mbrt.SomeMethod(callingDomainName);

        // Unload the second AppDomain. This deletes its object and
        // invalidates the proxy object.
        AppDomain.Unload(ad2);
        try
        {
            // Call the method again. Note that this time it fails
            // because the second AppDomain was unloaded.
            mbrt.SomeMethod(callingDomainName);
            Console.WriteLine("Sucessful call.");
        }
        catch(AppDomainUnloadedException)
        {
            Console.WriteLine("Failed call; this is expected.");
        }
    }
}

// Because this class is derived from MarshalByRefObject, a proxy
// to a MarshalByRefType object can be returned across an AppDomain
// boundary.
public class MarshalByRefType : MarshalByRefObject
{
    //  Call this method via a proxy.
    public void SomeMethod(string callingDomainName)
    {
        // Get this AppDomain's settings and display some of them.
        AppDomainSetup ads = AppDomain.CurrentDomain.SetupInformation;
        Console.WriteLine("AppName={0}, AppBase={1}, ConfigFile={2}",
            ads.ApplicationName,
            ads.ApplicationBase,
            ads.ConfigurationFile
        );

        // Display the name of the calling AppDomain and the name
        // of the second domain.
        // NOTE: The application's thread has transitioned between
        // AppDomains.
        Console.WriteLine("Calling from '{0}' to '{1}'.",
            callingDomainName,
            Thread.GetDomain().FriendlyName
        );
    }
}

/* This code produces output similar to the following:

AppDomainX.exe
AppDomainX, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
AppName=, AppBase=C:\AppDomain\bin, ConfigFile=C:\AppDomain\bin\AppDomainX.exe.config
Calling from 'AppDomainX.exe' to 'AD #2'.
Failed call; this is expected.
 */

Remarks

Application domains, which are represented by AppDomain objects, help provide isolation, unloading, and security boundaries for executing managed code.

  • Use application domains to isolate tasks that might bring down a process. If the state of the AppDomain that's executing a task becomes unstable, the AppDomain can be unloaded without affecting the process. This is important when a process must run for long periods without restarting. You can also use application domains to isolate tasks that should not share data.

  • If an assembly is loaded into the default application domain, it cannot be unloaded from memory while the process is running. However, if you open a second application domain to load and execute the assembly, the assembly is unloaded when that application domain is unloaded. Use this technique to minimize the working set of long-running processes that occasionally use large DLLs.

Note

On .NET Core, the AppDomain implementation is limited by design and does not provide isolation, unloading, or security boundaries. For .NET Core, there is exactly one AppDomain. Isolation and unloading are provided through AssemblyLoadContext. Security boundaries should be provided by process boundaries and appropriate remoting techniques.

Multiple application domains can run in a single process; however, there is not a one-to-one correlation between application domains and threads. Several threads can belong to a single application domain, and while a given thread is not confined to a single application domain, at any given time, a thread executes in a single application domain.

Application domains are created using the CreateDomain method. AppDomain instances are used to load and execute assemblies (Assembly). When an AppDomain is no longer in use, it can be unloaded.

The AppDomain class implements a set of events that enable applications to respond when an assembly is loaded, when an application domain will be unloaded, or when an unhandled exception is thrown.

For more information on using application domains, see Application Domains.

This class implements the MarshalByRefObject, _AppDomain, and IEvidenceFactory interfaces.

You should never create a remotable wrapper for an AppDomain object. Doing so could publish a remote reference to that AppDomain, exposing methods such as CreateInstance to remote access and effectively destroying code access security for that AppDomain. Malicious clients connecting to the remoted AppDomain could obtain access to any resource the AppDomain itself has access to. Do not create remotable wrappers for any type that extends MarshalByRefObject and that implements methods that could be used by malicious clients to bypass the security system.

Caution

The default value for the AppDomainSetup.DisallowCodeDownload property is false. This setting is unsafe for services. To prevent services from downloading partially trusted code, set this property to true.

Properties

ActivationContext

Gets the activation context for the current application domain.

ApplicationIdentity

Gets the identity of the application in the application domain.

ApplicationTrust

Gets information describing permissions granted to an application and whether the application has a trust level that allows it to run.

BaseDirectory

Gets the base directory that the assembly resolver uses to probe for assemblies.

CurrentDomain

Gets the current application domain for the current Thread.

DomainManager

Gets the domain manager that was provided by the host when the application domain was initialized.

DynamicDirectory

Gets the directory that the assembly resolver uses to probe for dynamically created assemblies.

Evidence

Gets the Evidence associated with this application domain.

FriendlyName

Gets the friendly name of this application domain.

Id

Gets an integer that uniquely identifies the application domain within the process.

IsFullyTrusted

Gets a value that indicates whether assemblies that are loaded into the current application domain execute with full trust.

IsHomogenous

Gets a value that indicates whether the current application domain has a set of permissions that is granted to all assemblies that are loaded into the application domain.

MonitoringIsEnabled

Gets or sets a value that indicates whether CPU and memory monitoring of application domains is enabled for the current process. Once monitoring is enabled for a process, it cannot be disabled.

MonitoringSurvivedMemorySize

Gets the number of bytes that survived the last collection and that are known to be referenced by the current application domain.

MonitoringSurvivedProcessMemorySize

Gets the total bytes that survived from the last collection for all application domains in the process.

MonitoringTotalAllocatedMemorySize

Gets the total size, in bytes, of all memory allocations that have been made by the application domain since it was created, without subtracting memory that has been collected.

MonitoringTotalProcessorTime

Gets the total processor time that has been used by all threads while executing in the current application domain, since the process started.

PermissionSet
Obsolete.

Gets the permission set of a sandboxed application domain.

RelativeSearchPath

Gets the path under the base directory where the assembly resolver should probe for private assemblies.

SetupInformation

Gets the application domain configuration information for this instance.

ShadowCopyFiles

Gets an indication whether the application domain is configured to shadow copy files.

Methods

AppendPrivatePath(String)
Obsolete.
Obsolete.
Obsolete.

Appends the specified directory name to the private path list.

ApplyPolicy(String)

Returns the assembly display name after policy has been applied.

ClearPrivatePath()
Obsolete.
Obsolete.
Obsolete.

Resets the path that specifies the location of private assemblies to the empty string ("").

ClearShadowCopyPath()
Obsolete.
Obsolete.
Obsolete.

Resets the list of directories containing shadow copied assemblies to the empty string ("").

CreateComInstanceFrom(String, String, Byte[], AssemblyHashAlgorithm)

Creates a new instance of a specified COM type. Parameters specify the name of a file that contains an assembly containing the type and the name of the type.

CreateComInstanceFrom(String, String)

Creates a new instance of a specified COM type. Parameters specify the name of a file that contains an assembly containing the type and the name of the type.

CreateDomain(String, Evidence, AppDomainSetup, PermissionSet, StrongName[])

Creates a new application domain using the specified name, evidence, application domain setup information, default permission set, and array of fully trusted assemblies.

CreateDomain(String, Evidence, AppDomainSetup)

Creates a new application domain using the specified name, evidence, and application domain setup information.

CreateDomain(String, Evidence, String, String, Boolean, AppDomainInitializer, String[])

Creates a new application domain with the given name, using evidence, application base path, relative search path, and a parameter that specifies whether a shadow copy of an assembly is to be loaded into the application domain. Specifies a callback method that is invoked when the application domain is initialized, and an array of string arguments to pass the callback method.

CreateDomain(String, Evidence, String, String, Boolean)

Creates a new application domain with the given name, using evidence, application base path, relative search path, and a parameter that specifies whether a shadow copy of an assembly is to be loaded into the application domain.

CreateDomain(String, Evidence)

Creates a new application domain with the given name using the supplied evidence.

CreateDomain(String)
Obsolete.

Creates a new application domain with the specified name.

CreateInstance(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[], Evidence)
Obsolete.

Creates a new instance of the specified type defined in the specified assembly. Parameters specify a binder, binding flags, constructor arguments, culture-specific information used to interpret arguments, activation attributes, and authorization to create the type.

CreateInstance(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[])

Creates a new instance of the specified type defined in the specified assembly. Parameters specify a binder, binding flags, constructor arguments, culture-specific information used to interpret arguments, and optional activation attributes.

CreateInstance(String, String, Object[])

Creates a new instance of the specified type defined in the specified assembly. A parameter specifies an array of activation attributes.

CreateInstance(String, String)

Creates a new instance of the specified type defined in the specified assembly.

CreateInstanceAndUnwrap(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[], Evidence)
Obsolete.

Creates a new instance of the specified type. Parameters specify the name of the type, and how it is found and created.

CreateInstanceAndUnwrap(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[])

Creates a new instance of the specified type defined in the specified assembly, specifying whether the case of the type name is ignored; the binding attributes and the binder that are used to select the type to be created; the arguments of the constructor; the culture; and the activation attributes.

CreateInstanceAndUnwrap(String, String, Object[])

Creates a new instance of the specified type. Parameters specify the assembly where the type is defined, the name of the type, and an array of activation attributes.

CreateInstanceAndUnwrap(String, String)

Creates a new instance of the specified type. Parameters specify the assembly where the type is defined, and the name of the type.

CreateInstanceFrom(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[], Evidence)
Obsolete.

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFrom(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[])

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFrom(String, String, Object[])

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFrom(String, String)

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFromAndUnwrap(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[], Evidence)
Obsolete.

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFromAndUnwrap(String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[])

Creates a new instance of the specified type defined in the specified assembly file, specifying whether the case of the type name is ignored; the binding attributes and the binder that are used to select the type to be created; the arguments of the constructor; the culture; and the activation attributes.

CreateInstanceFromAndUnwrap(String, String, Object[])

Creates a new instance of the specified type defined in the specified assembly file.

CreateInstanceFromAndUnwrap(String, String)

Creates a new instance of the specified type defined in the specified assembly file.

CreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.

(Inherited from MarshalByRefObject)
DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, Evidence, PermissionSet, PermissionSet, PermissionSet)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, evidence, and permission requests.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, Evidence)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, and evidence.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, IEnumerable<CustomAttributeBuilder>, SecurityContextSource)

Defines a dynamic assembly with the specified name, access mode, and custom attributes, and using the specified source for its security context.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, IEnumerable<CustomAttributeBuilder>)

Defines a dynamic assembly with the specified name, access mode, and custom attributes.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, PermissionSet, PermissionSet, PermissionSet)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, and permission requests.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, Boolean, IEnumerable<CustomAttributeBuilder>)

Defines a dynamic assembly using the specified name, access mode, storage directory, and synchronization option.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, Evidence, PermissionSet, PermissionSet, PermissionSet, Boolean, IEnumerable<CustomAttributeBuilder>)
Obsolete.

Defines a dynamic assembly with the specified name, access mode, storage directory, evidence, permission requests, synchronization option, and custom attributes.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, Evidence, PermissionSet, PermissionSet, PermissionSet, Boolean)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, storage directory, evidence, permission requests, and synchronization option.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, Evidence, PermissionSet, PermissionSet, PermissionSet)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, storage directory, evidence, and permission requests.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, Evidence)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, storage directory, and evidence.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String, PermissionSet, PermissionSet, PermissionSet)
Obsolete.

Defines a dynamic assembly using the specified name, access mode, storage directory, and permission requests.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, String)

Defines a dynamic assembly using the specified name, access mode, and storage directory.

DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess)

Defines a dynamic assembly with the specified name and access mode.

DoCallBack(CrossAppDomainDelegate)

Executes the code in another application domain that is identified by the specified delegate.

Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
ExecuteAssembly(String, Evidence, String[], Byte[], AssemblyHashAlgorithm)
Obsolete.

Executes the assembly contained in the specified file, using the specified evidence, arguments, hash value, and hash algorithm.

ExecuteAssembly(String, Evidence, String[])
Obsolete.

Executes the assembly contained in the specified file, using the specified evidence and arguments.

ExecuteAssembly(String, Evidence)
Obsolete.

Executes the assembly contained in the specified file, using the specified evidence.

ExecuteAssembly(String, String[], Byte[], AssemblyHashAlgorithm)
Obsolete.

Executes the assembly contained in the specified file, using the specified arguments, hash value, and hash algorithm.

ExecuteAssembly(String, String[])

Executes the assembly contained in the specified file, using the specified arguments.

ExecuteAssembly(String)

Executes the assembly contained in the specified file.

ExecuteAssemblyByName(AssemblyName, Evidence, String[])
Obsolete.

Executes the assembly given an AssemblyName, using the specified evidence and arguments.

ExecuteAssemblyByName(AssemblyName, String[])

Executes the assembly given an AssemblyName, using the specified arguments.

ExecuteAssemblyByName(String, Evidence, String[])
Obsolete.

Executes the assembly given its display name, using the specified evidence and arguments.

ExecuteAssemblyByName(String, Evidence)
Obsolete.

Executes an assembly given its display name, using the specified evidence.

ExecuteAssemblyByName(String, String[])

Executes the assembly given its display name, using the specified arguments.

ExecuteAssemblyByName(String)

Executes an assembly given its display name.

GetAssemblies()

Gets the assemblies that have been loaded into the execution context of this application domain.

GetCurrentThreadId()
Obsolete.
Obsolete.
Obsolete.
Obsolete.

Gets the current thread identifier.

GetData(String)

Gets the value stored in the current application domain for the specified name.

GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetLifetimeService()
Obsolete.

Retrieves the current lifetime service object that controls the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
GetType()

Gets the type of the current instance.

GetType()

Gets the Type of the current instance.

(Inherited from Object)
InitializeLifetimeService()

Gives the AppDomain an infinite lifetime by preventing a lease from being created.

InitializeLifetimeService()
Obsolete.

Obtains a lifetime service object to control the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
IsCompatibilitySwitchSet(String)

Gets a nullable Boolean value that indicates whether any compatibility switches are set, and if so, whether the specified compatibility switch is set.

IsDefaultAppDomain()

Returns a value that indicates whether the application domain is the default application domain for the process.

IsFinalizingForUnload()

Indicates whether this application domain is unloading, and the objects it contains are being finalized by the common language runtime.

Load(AssemblyName, Evidence)
Obsolete.

Loads an Assembly given its AssemblyName.

Load(AssemblyName)

Loads an Assembly given its AssemblyName.

Load(Byte[], Byte[], Evidence)
Obsolete.

Loads the Assembly with a common object file format (COFF) based image containing an emitted Assembly. The raw bytes representing the symbols for the Assembly are also loaded.

Load(Byte[], Byte[])

Loads the Assembly with a common object file format (COFF) based image containing an emitted Assembly. The raw bytes representing the symbols for the Assembly are also loaded.

Load(Byte[])

Loads the Assembly with a common object file format (COFF) based image containing an emitted Assembly.

Load(String, Evidence)
Obsolete.

Loads an Assembly given its display name.

Load(String)

Loads an Assembly given its display name.

MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
MemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.

(Inherited from MarshalByRefObject)
ReflectionOnlyGetAssemblies()

Returns the assemblies that have been loaded into the reflection-only context of the application domain.

SetAppDomainPolicy(PolicyLevel)
Obsolete.

Establishes the security policy level for this application domain.

SetCachePath(String)
Obsolete.
Obsolete.
Obsolete.

Establishes the specified directory path as the location where assemblies are shadow copied.

SetData(String, Object, IPermission)

Assigns the specified value to the specified application domain property, with a specified permission to demand of the caller when the property is retrieved.

SetData(String, Object)

Assigns the specified value to the specified application domain property.

SetDynamicBase(String)
Obsolete.
Obsolete.
Obsolete.

Establishes the specified directory path as the base directory for subdirectories where dynamically generated files are stored and accessed.

SetPrincipalPolicy(PrincipalPolicy)

Specifies how principal and identity objects should be attached to a thread if the thread attempts to bind to a principal while executing in this application domain.

SetShadowCopyFiles()
Obsolete.
Obsolete.
Obsolete.

Turns on shadow copying.

SetShadowCopyPath(String)
Obsolete.
Obsolete.
Obsolete.

Establishes the specified directory path as the location of assemblies to be shadow copied.

SetThreadPrincipal(IPrincipal)

Sets the default principal object to be attached to threads if they attempt to bind to a principal while executing in this application domain.

ToString()

Obtains a string representation that includes the friendly name of the application domain and any context policies.

Unload(AppDomain)
Obsolete.

Unloads the specified application domain.

Events

AssemblyLoad

Occurs when an assembly is loaded.

AssemblyResolve

Occurs when the resolution of an assembly fails.

DomainUnload

Occurs when an AppDomain is about to be unloaded.

FirstChanceException

Occurs when an exception is thrown in managed code, before the runtime searches the call stack for an exception handler in the application domain.

ProcessExit

Occurs when the default application domain's parent process exits.

ReflectionOnlyAssemblyResolve

Occurs when the resolution of an assembly fails in the reflection-only context.

ResourceResolve

Occurs when the resolution of a resource fails because the resource is not a valid linked or embedded resource in the assembly.

TypeResolve

Occurs when the resolution of a type fails.

UnhandledException

Occurs when an exception is not caught.

Explicit Interface Implementations

_AppDomain.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

_AppDomain.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can then be used to get the type information for an interface.

_AppDomain.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

_AppDomain.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

Applies to

Product Versions
.NET Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1

See also