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Q244751: PRB: Winsock Control does not Fire Error Event in all Cases

Article: Q244751
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0,6.0
Operating System(s): 
Keyword(s): kbnetwork kbAPI kbCtrl kbSDKPlatform kbSDKWin32 kbVBp600 kbDSupport kbGrpDSNet
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

When using the Winsock Control in Visual Basic, setting the LocalPort property
to a port value that is already in use on the local computer raises a Visual
Basic Run-time error when the Connect or Bind method is called. The Run-time
error is as follows:

  '10048' - "Address in use".

Normally this could be captured using the Error Event of the Winsock Control, but
even when the Error event is present for the control, the Error event is never
fired and the Run-time error message box is displayed.

RESOLUTION
==========

A valid workaround is to use Visual Basic's standard Error Handling mechanism to
catch the error as illustrated in the following code snippet:

  On Error Resume Next
  Winsock1.Connect
  If Err then 
     ' handle the error here
  End if

Simply use the On Error method around the Connect or Bind method of the Winsock
Control to capture this error.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

- Create a New Project.

- Add the Winsock Control to the Project.

- Place the Winsock Control on the Form.

- Add the following code:

  Private Sub Form_Load()
    Winsock1.RemoteHost = "localhost"
    Winsock1.RemotePort = 7	' connect to echo server from Simple TCP/IP Services available on NT
    Winsock1.LocalPort = 80	' pick a port that is in use... 80 is IIS (http)  
    Winsock1.Connect  ' this line of code will force the run-time error even the error event is included below
  End Sub

  Private Sub Winsock1_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
    CancelDisplay = True
    MsgBox "Error"
  End Sub

When this code is run the Winsock1_Error handler is never called even though a
Winsock Control error has occurred. Using the work-around mentioned earlier
causes Visual Basic's normal error handling to handle the error.

Additional query words:

======================================================================
Keywords          : kbnetwork kbAPI kbCtrl kbSDKPlatform kbSDKWin32 kbVBp600 kbDSupport kbGrpDSNet 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Version           : WINDOWS:5.0,6.0
Issue type        : kbprb

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