How to raise events from a serviced component?

microsoft.public.dotnet.framework

16 May 2006 8:55 AM

Stefan Frutiger

Hi

I have the problem that when raising events on a remote server the event is
not passed back to the client but somehow executed on the server. If I don't
register (in GAC) the client library with the ClientObserver class on the
remote server I get an exception telling me that the assembly is not found
on the server. Why I have to register the client library in the servers GAC?
This doesn't sound locigal, does it? However, the MsgBox is displayed on the
servers screen, which is very bad.

Even when I install all the components on the same machine I can verify with
the Process ID that the MsgBox is executed in the dllhost.exe process
instead of in the client application. Is there something wrong with my code?

Here's the sample in VB .NET 2.0: (All assemblies have a strong name...)

'***************************
'Server Part
'***************************

Imports System.EnterpriseServices
Imports System.Runtime.InteropServices
Imports System.ComponentModel

'Use a Server Application (out-of-process) --> the component runs in
dllhost.exe
<Assembly: ApplicationActivation(ActivationOption.Server)>
<Assembly:
ApplicationAccessControl([AccessChecksLevel]:=AccessChecksLevelOption.ApplicationComponent,
_
                                    [Authentication]:=AuthenticationOption.Packet,
_
                                    [ImpersonationLevel]:=ImpersonationLevelOption.Impersonate,
_
                                    [Value]:=False)>   'Turn off
authentication

<Transaction(TransactionOption.Required)> _
<EventTrackingEnabled(True)> _
<ObjectPooling(False)> _
<ClassInterface(ClassInterfaceType.AutoDual)> _
Public Class TestTransaction
    Inherits ServicedComponent

    Public Event TestEvent As CancelEventHandler

    <AutoComplete()> _
    Public Sub Test()

        'Do something useful...

        'Ask user to Cancel the COM+ transaction
        Dim cancelEventArgs As New CancelEventArgs
        RaiseEvent TestEvent(Me, cancelEventArgs)
        If cancelEventArgs.Cancel Then
            Throw New Exception("Transaction aborted by user!")
        End If

    End Sub

End Class

'***************************
'Client Part
'***************************

<Serializable()> _
Public Class ClientObserver

    <NonSerialized()> _
    Public WithEvents Server As TestTransaction

    Private Sub Server_TestEvent(ByVal sender As Object, ByVal e As
System.ComponentModel.CancelEventArgs) Handles Server.TestEvent

        If MsgBox("Click [Cancel] to abort and rollback the transaction.", _
                    MsgBoxStyle.Question Or MsgBoxStyle.OkCancel) =
MsgBoxResult.Cancel Then
            e.Cancel = True
        End If

    End Sub

End Class

'***************************

Thanks for help!
Stefan

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