Unexpected behavior when using VB6 with COM interoperability (C #)

Question

We use COM Interop (C #) so that the VB6 application can send data to the server. After the server receives the data, the managed code will raise a DataSent event. This event is triggered only after the correlation identifier is returned to the original subscriber.

In about 1% of cases, we encountered VB6 executing a raised event, before the function that originally sent the data was completed.

Using the following code:

' InteropTester.COMEvents is the C# object '
Dim WithEvents m_ManagedData as InteropTester.COMEvents

Private Sub send_data()

   Set m_ManagedData = new COMEvents
   Dim id as Integer
   ' send 5 to using the managed interop object '
   id = m_ManagedData.SendData(5)
   LogData "ID " & id & " was returned"
   m_correlationIds.Add id

End Sub

Private Sub m_ManagedData_DataSent(ByVal sender as Variant, ByVal id as Integer)
   LogData "Data was successfully sent to C#"
   ' check if the returned ID is in the m_correlationIds collection goes here'
End Sub   

We can check if id with value is returned when we call m_ManagedData.SendData (5), but the logs show that m_ManagedData_DataSent is sometimes called before send_data ends.

VB6 Loop , , DataSent send_data()? DoEvents, VB6 .

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Answer 1

, COM- , , VB6. LogData?