how to set the Principal policy to WindwosPrincipal ?

[loyal]

hi all I am practising on MCAD training kit book

 

and here's an example I tried but gave me an exception

 

specified cast is not valid

 

and here's the code as an example in my book

 

' This example assumes that the Principal policy has been set to 
' WindowsPrincipal.
Dim myPrincipal As WindowsPrincipal
' Gets a reference to the current WindowsPrincipal
myPrincipal = CType(Threading.Thread.CurrentPrincipal, _
  WindowsPrincipal)
Dim myIdentity As WindowsIdentity
' Gets the WindowsIdentity of the current principal
myIdentity = CType(myPrincipal.Identity, WindowsIdentity)
' Displays the username of the current user
MessageBox.Show(myIdentity.Name)

[PlausiblyDamp]

There is no valid cast from a GenericPrinciple (which Threading.Thread.CurrentPrincipal is) and a WindowsPrinciple.

 

They both implement the same interface (IPrinciple) so either could be casted to IPrinciple, neither could be casted to the other.

 

The following should work

' This example assumes that the Principal policy has been set to 
' WindowsPrincipal.
Dim myPrincipal As IPrincipal
' Gets a reference to the current WindowsPrincipal
myPrincipal = DirectCast(Threading.Thread.CurrentPrincipal, _
  IPrincipal)
Dim myIdentity As IIdentity
' Gets the WindowsIdentity of the current principal
myIdentity = DirectCast(myPrincipal.Identity, IIdentity)
' Displays the username of the current user
MessageBox.Show(myIdentity.Name)

[loyal]

yeah thanks

 

but I found this script later in my book to set the

 

Principal Policy To WindowsPrincipal

 

AppDomain.CurrentDomain.SetPrincipalPolicy(Security.Principal.PrincipalPolicy.WindowsPrincipal)

[Derek Stone]

CurrentPrincipal is defined as IPrincipal, not GenericPrincipal as stated above. It can easily accept any class that implements IPrincipal.