assembly binding to redirect to a different assebly file

Question

Hello,

i transfered a class to a different assembly but kept the same namespaces. My application is deserializing a file that contains type references to this class and now i get exceptions because it is looking for the old assebly. So i created a SerializationBinder decendant to handle that, but although the BindToType method is called for other types that have also been moved, it is never called for the class type that is causing the exception.

The next thing i did was to add a CodeBase reference to the applications config file to point to new assebly that contais that type but still i get the same excpetion that the old assembly file cannot be located

My original class was structured like this:

Assembly file MyLib.Classes.dll (version 1.0.0.0)

     Namespace MyLib.Classes

         Public Class TestClass

and then like this:

Assembly file MyLib.dll (version 1.0.0.1)

     Namespace MyLib.Classes

         Public Class TestClass

my serializationbinder looks like this:

Public Class CustomSerializationBinder
    Inherits Runtime.Serialization.SerializationBinder

    Public Overrides Function BindToType(assemblyName As String, typeName As String) As System.Type

        assemblyName = assemblyName.Replace("MyLib.Classes, Version=1.0.0.0", "MyLib Version=1.0.0.1")
        typeName = assemblyName.Replace("MyLib.Classes, Version=1.0.0.0", "MyLib Version=1.0.0.1")
        Return Type.GetType(String.Format("{0}, {1}", typeName, assemblyName))

    End Function

End Class

the deserialization code is like this:

Dim Bytes() As Byte = value
Using Stream As New IO.MemoryStream(Bytes) With {.Position = 0}
    Dim b As New Runtime.Serialization.Formatters.Binary.BinaryFormatter() With {.Binder = New CustomSerializationBinder()}
    Return b.Deserialize(Stream)
End Using

and finally my configuration file looks like this:

<runtime>
   <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">  
      <dependentAssembly>
         <assemblyIdentity name="MyLib.Classes" publicKeyToken="e9a4f5adb9bd741c" culture="neutral" />
         <CodeBase Version="1.0.0.1" href="file:///c:\temp\MyLib.dll" />
      </dependentAssembly>
   </assemblyBinding>
</runtime>

MyLib.Classes.dll and MyLib.dll are strong name assemblies.

Upon deserialization i get the following exception:

Message: Could not load file or assembly 'MyLib.Classes, Version=1.0.0.0, Culture=neutral, PublicKeyToken=e9a4f5adb9bd741c' or one of its dependencies. The system cannot find the file specified.

Stack Trace:   at System.Reflection.Assembly._GetType(String name, Boolean throwOnError, Boolean ignoreCase)
   at System.UnitySerializationHolder.GetRealObject(StreamingContext context)
   at System.Runtime.Serialization.ObjectManager.ResolveObjectReference(ObjectHolder holder)
   at System.Runtime.Serialization.ObjectManager.DoFixups()
   at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream)
   at .......

Fusion.Log:=== Pre-bind state information ===
LOG: User = PC2\Theodore
LOG: DisplayName = MyLib.Classes, Version=1.0.0.0, Culture=neutral, PublicKeyToken=e9a4f5adb9bd741c
 (Fully-specified)
LOG: Appbase = file:///D:/.../MyApp/bin/x86/Debug/
LOG: Initial PrivatePath = NULL
Calling assembly : (Unknown)
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: D:\...\MyApp\bin\x86\Debug\MyApp.vshost.exe.Config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v2.0.50727\config\machine.config.
LOG: Post-policy reference: MyLib.Classes, Version=1.0.0.0, Culture=neutral, PublicKeyToken=e9a4f5adb9bd741c
LOG: Attempting download of new URL file:///D:/.../MyApp/bin/x86/Debug/MyLib.Classes.DLL.
LOG: Attempting download of new URL file:///D:/.../MyApp/bin/x86/Debug/MyLib.Classes.DLL/MyLib.Classes.DLL.
LOG: Attempting download of new URL file:///D:/.../MyApp/bin/x86/Debug/MyLib.Classes.EXE.
LOG: Attempting download of new URL file:///D:/.../MyApp/bin/x86/Debug/MyLib.Classes.EXE/MyLib.Classes.EXE.

Is there a way around this problem?

Regards,

Theodore

---

Theo

Answer 1

I solved this problem on own and i share it for the benefit of everyone who cares to know.

I added a handler to the application domain's AssemblyResolve event and there i loaded the new assembly.

AddHandler AppDomain.CurrentDomain.AssemblyResolve, AddressOf AssemblyResolver

Private Function AssemblyResolver(ByVal source As Object, ByVal e As ResolveEventArgs) As Reflection.Assembly

        If e.Name.Contains("MyLib.Classes") Then
            Return Reflection.Assembly.Load("MyLib, Version=1.0.0.1, Culture=neutral, PublicKeyToken=e9a4f5adb9bd741c")

        Else : Return Nothing 'Reflection.Assembly.Load(e.Name)
        End If

End Function

---

Theo