AppDomain | C # in a Nutshell, Second Edition

AppDomain

CF 1.0, ECMA 1.0, marshal by reference

System (mscorlib.dll)

sealed class

This class represents an abstract separation within the executing process, which mimics the separation between processes running on a single machine. As a result, a single .NET process can host multiple other processes that offer the isolation found between processes, while keeping the low overhead of a single process.

Every .NET process created has at least one AppDomain , even when running a simple command shell-driven application, such as Hello, world , created by the shim code at the start of a .NET executable file. Applications that act as containers, however, can create multiple AppDomains , loading assemblies into each AppDomain independently of one another. This is, in fact, precisely how ASP.NET keeps multiple web applications separate from one another, so that an exception thrown from within one won't tear down the entire IIS process.

Creating a new AppDomain involves using the static CreateDomain( ) method. This method is overloaded four ways, but the most common use is simply to pass in a friendly name for the AppDomain . When finished with a given AppDomain , use the Unload( ) method to close down the AppDomain and all objects stored within it. Should a .NET programmer wish to obtain a reference to the AppDomain she is currently executing within, the static property CurrentDomain returns the current AppDomain .

Each AppDomain contains an entirely separate list of loaded assemblies accessible via the GetAssemblies( ) method, which returns the list of assemblies loaded for this particular AppDomain . AppDomains can also create instances of types within the given AppDomain , using the CreateInstance( ) family of methods . An AppDomain can also load and execute the entry point of an assembly using the ExecuteAssembly( ) method, or it can load an assembly directly using one of the Load( ) methods. AppDomains even support the ability to create dynamic (that is, transient or temporary) assemblies through the DefineDynamicAssembly( ) method.

AppDomains also offer a number of .NET events for interested consumers, notifying .NET programmers when an assembly has been loaded ( AssemblyLoad ), when an exception has been thrown out of a thread within that assembly ( UnhandledException ), or when the AppDomain or the process containing itis being unloaded and torn down ( DomainUnload and ProcessExit ). .NET programmers can use these events to perform necessary actions, such as loading an assembly from an alternative location when an assembly fails to load ( AssemblyResolve ).

AppDomain also contains a number of properties, which act in a role similar to environment variables within a process. These AppDomain properties are, like environment variables, simple name-value mapping pairs, retrievable in one of two ways: via the GetData( ) method or via a set of predefined properties on the AppDomain class (such as BaseDirectory ).

 public sealed class  AppDomain  : MarshalByRefObject,  _AppDomain, System.Security.IEvidenceFactory {  // Public Static Properties  public static AppDomain  CurrentDomain  {get; }  // Public Instance Properties  public string  BaseDirectory  {get; }  // implements _AppDomain  public string  DynamicDirectory  {get; }  // implements _AppDomain  public Evidence  Evidence  {get; }  // implements System.Security.IEvidenceFactory  public string  FriendlyName  {get; }  // implements _AppDomain  public string  RelativeSearchPath  {get; }  // implements _AppDomain  public AppDomainSetup  SetupInformation  {get; }    public bool  ShadowCopyFiles  {get; }  // implements _AppDomain   // Public Static Methods  public static AppDomain  CreateDomain  (string   friendlyName   );    public static AppDomain  CreateDomain  (string   friendlyName   , System.Security.Policy.Evidence   securityInfo   );    public static AppDomain  CreateDomain  (string   friendlyName   , System.Security.Policy.Evidence   securityInfo   ,          AppDomainSetup   info   );    public static AppDomain  CreateDomain  (string   friendlyName   , System.Security.Policy.Evidence   securityInfo   ,          string   appBasePath   , string   appRelativeSearchPath   , bool   shadowCopyFiles   );    public static int  GetCurrentThreadId  ( );    public static void  Unload  (AppDomain   domain   );  // Public Instance Methods  public void  AppendPrivatePath  (string   path   );  // implements _AppDomain  public void  ClearPrivatePath  ( );  // implements _AppDomain  public void  ClearShadowCopyPath  ( );  // implements _AppDomain  public ObjectHandle  CreateComInstanceFrom  (string   assemblyName   , string   typeName   );    public ObjectHandle  CreateComInstanceFrom  (string   assemblyFile   , string   typeName   , byte[ ]   hashValue   ,          System.Configuration.Assemblies.AssemblyHashAlgorithm   hashAlgorithm   );    public ObjectHandle  CreateInstance  (string   assemblyName   , string   typeName   )  // implements _AppDomain  public ObjectHandle  CreateInstance  (string   assemblyName   , string   typeName   , bool   ignoreCase   ,           System.Reflection.BindingFlags   bindingAttr   , System.Reflection.Binder   binder   , object[ ]   args   ,          System.Globalization.CultureInfo   culture   , object[ ]   activationAttributes   ,          System.Security.Policy.Evidence   securityAttributes   )  // implements _AppDomain  public ObjectHandle  CreateInstance  (string   assemblyName   , string   typeName   ,          object[ ]   activationAttributes   )  // implements _AppDomain  public object  CreateInstanceAndUnwrap  (string   assemblyName   , string   typeName   );    public object  CreateInstanceAndUnwrap  (string   assemblyName   , string   typeName   , bool   ignoreCase   ,          System.Reflection.BindingFlags   bindingAttr   , System.Reflection.Binder   binder   , object[ ]   args   ,          System.Globalization.CultureInfo   culture   , object[ ]   activationAttributes   ,          System.Security.Policy.Evidence   securityAttributes   );    public object  CreateInstanceAndUnwrap  (string   assemblyName   , string   typeName   , object[ ]   activationAttributes   );    public ObjectHandle  CreateInstanceFrom  (string   assemblyFile   , string   typeName   );  // implements _AppDomain  public ObjectHandle  CreateInstanceFrom  (string   assemblyFile   , string   typeName   , bool   ignoreCase   ,          System.Reflection.BindingFlags   bindingAttr   , System.Reflection.Binder   binder   , object[ ]   args   ,          System.Globalization.CultureInfo   culture   , object[ ]   activationAttributes   ,          System.Security.Policy.Evidence   securityAttributes   )  // implements _AppDomain  public ObjectHandle  CreateInstanceFrom  (string   assemblyFile   , string   typeName   ,          object[ ]   activationAttributes   )  // implements _AppDomain  public object  CreateInstanceFromAndUnwrap  (string   assemblyName   , string   typeName   );    public object  CreateInstanceFromAndUnwrap  (string   assemblyName   , string   typeName   , bool   ignoreCase   ,         System.Reflection.BindingFlags   bindingAttr   , System.Reflection.Binder   binder   , object[ ]   args   ,          System.Globalization.CultureInfo   culture   , object[ ]   activationAttributes   ,          System.Security.Policy.Evidence   securityAttributes   );    public object  CreateInstanceFromAndUnwrap  (string   assemblyName   , string   typeName   , object[ ]   activationAttributes   );    public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,         System.Reflection.Emit.AssemblyBuilderAccess   access   ,  System.Security.Policy.Evidence   evidence   )  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , System.Security.Policy.Evidence   evidence   ,          System.Security.PermissionSet   requiredPermissions   , System.Security.PermissionSet   optionalPermissions   ,          System.Security.PermissionSet   refusedPermissions   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , System.Security.PermissionSet   requiredPermissions   ,         System.Security.PermissionSet   optionalPermissions   , System.Security.PermissionSet   refusedPermissions   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , string   dir   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , string   dir   , System.Security.Policy.Evidence   evidence   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , string   dir   , System.Security.Policy.Evidence   evidence   ,          System.Security.PermissionSet   requiredPermissions   , System.Security.PermissionSet   optionalPermissions   ,          System.Security.PermissionSet   refusedPermissions   );  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , string   dir   , System.Security.Policy.Evidence   evidence   ,          System.Security.PermissionSet   requiredPermissions   , System.Security.PermissionSet   optionalPermissions   ,          System.Security.PermissionSet   refusedPermissions   , bool   isSynchronized   )  // implements _AppDomain  public AssemblyBuilder  DefineDynamicAssembly  (System.Reflection.AssemblyName   name   ,          System.Reflection.Emit.AssemblyBuilderAccess   access   , string   dir   ,          System.Security.PermissionSet   requiredPermissions   , System.Security.PermissionSet   optionalPermissions   ,          System.Security.PermissionSet   refusedPermissions   )  // implements _AppDomain  public void  DoCallBack  (CrossAppDomainDelegate   callBackDelegate   )  // implements _AppDomain  public int  ExecuteAssembly  (string   assemblyFile   );  // implements _AppDomain  public int  ExecuteAssembly  (string   assemblyFile   ,          System.Security.Policy.Evidence   assemblySecurity   )  // implements _AppDomain  public int  ExecuteAssembly  (string   assemblyFile   , System.Security.Policy.Evidence   assemblySecurity   ,          string[ ]   args   );  // implements _AppDomain  public int  ExecuteAssembly  (string   assemblyFile   , System.Security.Policy.Evidence   assemblySecurity   ,          string[ ]   args   , byte[ ]   hashValue   , System.Configuration.Assemblies.AssemblyHashAlgorithm   hashAlgorithm   );    public Assembly[ ]  GetAssemblies  ( );  // implements _AppDomain  public object  GetData  (string   name   );  // implements _AppDomain  public Type  GetType  ( );  // overrides object  public override object  InitializeLifetimeService  ( );  // overrides MarshalByRefObject  public bool  IsFinalizingForUnload  ( );    public Assembly  Load  (System.Reflection.AssemblyName   assemblyRef   )  // implements _AppDomain  public Assembly  Load  (System.Reflection.AssemblyName   assemblyRef   ,          System.Security.Policy.Evidence   assemblySecurity   );  // implements _AppDomain  public Assembly  Load  (byte[ ]   rawAssembly   );  // implements _AppDomain  public Assembly  Load  (byte[ ]   rawAssembly   , byte[ ]   rawSymbolStore   );  // implements _AppDomain  public Assembly  Load  (byte[ ]   rawAssembly   , byte[ ]   rawSymbolStore   , System.Security.Policy.Evidence   securityEvidence   );  // implements _AppDomain  public Assembly  Load  (string   assemblyString   );  // implements _AppDomain  public Assembly  Load  (string   assemblyString   , System.Security.Policy.Evidence   assemblySecurity   )  // implements _AppDomain  public void  SetAppDomainPolicy  (System.Security.Policy.PolicyLevel   domainPolicy   )  // implements _AppDomain  public void  SetCachePath  (string   path   );  // implements _AppDomain  public void  SetData  (string   name   , object   data   );  // implements _AppDomain  public void  SetDynamicBase  (string   path   );    public void  SetPrincipalPolicy  (System.Security.Principal.PrincipalPolicy   policy   )  // implements _AppDomain  public void  SetShadowCopyFiles  ( );    public void  SetShadowCopyPath  (string   path   );  // implements _AppDomain  public void  SetThreadPrincipal  (System.Security.Principal.IPrincipal   principal   )  // implements _AppDomain  public override string  ToString  ( );  // overrides object   // Events  public event AssemblyLoadEventHandler  AssemblyLoad  ;  // implements _AppDomain  public event ResolveEventHandler  AssemblyResolve  ;  // implements _AppDomain  public event EventHandler  DomainUnload  ;  // implements _AppDomain  public event EventHandler  ProcessExit  ;  // implements _AppDomain  public event ResolveEventHandler  ResourceResolve  ;  // implements _AppDomain  public event ResolveEventHandler  TypeResolve  ;  // implements _AppDomain  public event UnhandledExceptionEventHandler  UnhandledException  ;  // implements _AppDomain  }

Hierarchy

Object MarshalByRefObject AppDomain(_AppDomain, System.Security.IEvidenceFactory)

Returned By

System.Threading.Thread.GetDomain( )