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AppDomain.Load Method (Byte())

Updated: March 2011

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

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

Public Function Load ( _
	rawAssembly As Byte() _
) As Assembly
Dim instance As AppDomain 
Dim rawAssembly As Byte()
Dim returnValue As [Assembly]

returnValue = instance.Load(rawAssembly)


Type: System.Byte()

An array of type byte that is a COFF-based image containing an emitted assembly.

Return Value

Type: System.Reflection.Assembly
The loaded assembly.




rawAssembly is Nothing.


rawAssembly is not a valid assembly.


Version 2.0 or later of the common language runtime is currently loaded and rawAssembly was compiled with a later version.


The operation is attempted on an unloaded application domain.


An assembly or module was loaded twice with two different evidences.

This method should be used only to load an assembly into the current application domain. This method is provided as a convenience for interoperability callers who cannot call the static Assembly.Load method. To load assemblies into other application domains, use a method such as CreateInstanceAndUnwrap.

For information that is common to all overloads of this method, see the Load(AssemblyName) method overload.

The following example demonstrates the use of loading a raw assembly.

For this code example to run, you must provide the fully qualified assembly name. For information about how to obtain the fully qualified assembly name, see Assembly Names.

Imports System
Imports System.IO
Imports System.Reflection
Imports System.Reflection.Emit

Module Test

   Sub Main()
      Dim currentDomain As AppDomain = AppDomain.CurrentDomain

      InstantiateMyType(currentDomain)      ' Failed!

      AddHandler currentDomain.AssemblyResolve, AddressOf MyResolver

      InstantiateMyType(currentDomain)      ' OK!
   End Sub 'Main

   Sub InstantiateMyType(domain As AppDomain)
	 ' You must supply a valid fully qualified assembly name here.
         domain.CreateInstance("Assembly text name, Version, Culture, PublicKeyToken", "MyType")
      Catch e As Exception
      End Try 
   End Sub 'InstantiateMyType

   ' Loads the content of a file to a byte array.  
   Function loadFile(filename As String) As Byte()
      Dim fs As New FileStream(filename, FileMode.Open)
      Dim buffer(CInt(fs.Length)) As Byte
      fs.Read(buffer, 0, buffer.Length)

      Return buffer
   End Function 'loadFile

   Function MyResolver(sender As Object, args As ResolveEventArgs) As System.Reflection.Assembly
      Dim domain As AppDomain = DirectCast(sender, AppDomain)

      ' Once the files are generated, this call is 
      ' actually no longer necessary.

      Dim rawAssembly As Byte() = loadFile("temp.dll")
      Dim rawSymbolStore As Byte() = loadFile("temp.pdb")
      Dim myAssembly As System.Reflection.Assembly = domain.Load(rawAssembly, rawSymbolStore)

      Return myAssembly
   End Function 'MyResolver

   ' Creates a dynamic assembly with symbol information 
   ' and saves them to temp.dll and temp.pdb 
   Sub EmitAssembly(domain As AppDomain)
      Dim assemblyName As New AssemblyName()
      assemblyName.Name = "MyAssembly" 

      Dim assemblyBuilder As AssemblyBuilder = domain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Save)
      Dim moduleBuilder As ModuleBuilder = assemblyBuilder.DefineDynamicModule("MyModule", "temp.dll", True)
      Dim typeBuilder As TypeBuilder = moduleBuilder.DefineType("MyType", TypeAttributes.Public)

      Dim constructorBuilder As ConstructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, Nothing)
      Dim ilGenerator As ILGenerator = constructorBuilder.GetILGenerator()
      ilGenerator.EmitWriteLine("MyType instantiated!")


   End Sub 'EmitAssembly

End Module 'Test

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

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




March 2011

Clarified that this method is not for loading assemblies into other application domains.

Customer feedback.