The Internet Transfer Control 5.0 "HEAD" request does not
work based on the documentation provided by Microsoft. There is no header
information being returned when the Execute method and "HEAD" request are sent
to the web server.
The Internet Transfer Control 5.0 "HEAD" request does not
work from Visual Basic 5.0. You need to use the WinInet APIs that are included
with the ActiveX SDK to get header information from your server. Specifically
the InternetOpen, InternetConnect, HttpOpenRequest, HttpSendRequest, and
HttpQueryInfo are the WinInet APIs you need to use. In the sample code below,
get the header information from:
The following code can be used to work around this problem:
Run Visual Basic or, if Visual Basic is already running,
choose New Project from the File menu (ALT, F, N). Form1 is created by default.
Add the following code to the general declarations section
of Form1:
Private Declare Function InternetOpen Lib "wininet.dll" _
Alias "InternetOpenA" _
(ByVal lpszCallerName As String, _
ByVal dwAccessType As Long, _
ByVal lpszProxyName As String, _
ByVal lpszProxyBypass As String, _
ByVal dwFlags As Long) As Long
Private Declare Function InternetConnect Lib "wininet.dll" _
Alias "InternetConnectA" _
(ByVal hInternetSession As Long, _
ByVal lpszServerName As String, _
ByVal nProxyPort As Integer, _
ByVal lpszUsername As String, _
ByVal lpszPassword As String, _
ByVal dwService As Long, _
ByVal dwFlags As Long, _
ByVal dwContext As Long) As Long
Private Declare Function HttpOpenRequest Lib "wininet.dll" _
Alias "HttpOpenRequestA" _
(ByVal hInternetSession As Long, _
ByVal lpszVerb As String, _
ByVal lpszObjectName As String, _
ByVal lpszVersion As String, _
ByVal lpszReferer As String, _
ByVal lpszAcceptTypes As Long, _
ByVal dwFlags As Long, _
ByVal dwContext As Long) As Long
Private Declare Function HttpSendRequest Lib "wininet.dll" _
Alias "HttpSendRequestA" _
(ByVal hHttpRequest As Long, _
ByVal sHeaders As String, _
ByVal lHeadersLength As Long, _
ByVal sOptional As String, _
ByVal lOptionalLength As Long) As Boolean
Private Declare Function HttpQueryInfo Lib "wininet.dll" _
Alias "HttpQueryInfoA" _
(ByVal hHttpRequest As Long, _
ByVal lInfoLevel As Long, _
ByVal sBuffer As Any, _
ByRef lBufferLength As Long, _
ByRef lIndex As Long) As Boolean
Private Declare Function InternetCloseHandle Lib "wininet.dll" _
(ByVal hInternetHandle As Long) As Boolean
From the Project menu, choose Components, and select the
Internet Transfer Control 5.0 into the project if it is not already loaded.
Place a Internet Transfer Control 5.0(Inet1) on Form1.
Place a ListBox Control(List1) on Form1.
Place a CommandButton (Command1) on Form1 and add the
following code.
Private Sub Command1_Click()
Dim hInternetOpen As Long
Dim hInternetConnect As Long
Dim hHttpOpenRequest As Long
Dim bRet As Boolean
hInternetOpen = 0
hInternetConnect = 0
hHttpOpenRequest = 0
' Use registry access settings.
Const INTERNET_OPEN_TYPE_PRECONFIG = 0
hInternetOpen = InternetOpen("http generic", _
INTERNET_OPEN_TYPE_PRECONFIG, _
vbNullString, _
vbNullString, _
0)
If hInternetOpen <> 0 Then
' Type of service to access.
Const INTERNET_SERVICE_HTTP = 3
Const INTERNET_DEFAULT_HTTP_PORT = 80
hInternetConnect = InternetConnect(hInternetOpen, _
"www.microsoft.com", _
INTERNET_DEFAULT_HTTP_PORT, _
vbNullString, _
"HTTP/1.0", _
INTERNET_SERVICE_HTTP, _
0, _
0)
If hInternetConnect <> 0 Then
' Brings the data across the wire even if it locally cached.
Const INTERNET_FLAG_RELOAD = &H80000000
hHttpOpenRequest = HttpOpenRequest(hInternetConnect, _
"HEAD", _
"default.htm", _
vbNullString, _
vbNullString, _
0, _
INTERNET_FLAG_RELOAD, _
0)
If hHttpOpenRequest <> 0 Then
bRet = HttpSendRequest(hHttpOpenRequest, _
vbNullString, _
0, _
vbNullString, _
0)
' Headers to query
Const HTTP_QUERY_CONTENT_TYPE = 1
Const HTTP_QUERY_VERSION = 18
Const HTTP_QUERY_SERVER = 37
Const HTTP_QUERY_REQUEST_METHOD = 45
If bRet Then
Dim sBuff As String * 1024
Dim lBuffLen As Long
lBuffLen = Len(sBuff)
'response headers
If (HttpQueryInfo(hHttpOpenRequest, _
HTTP_QUERY_CONTENT_TYPE, sBuff, lBuffLen, 0) _
= 1) Then
List1.AddItem sBuff
End If
If (HttpQueryInfo(hHttpOpenRequest, _
HTTP_QUERY_VERSION, sBuff, lBuffLen, 0) _
= 1) Then
List1.AddItem sBuff
End If
If (HttpQueryInfo(hHttpOpenRequest, _
HTTP_QUERY_SERVER, sBuff, lBuffLen, 0) _
= 1) Then
List1.AddItem sBuff
End If
If (HttpQueryInfo(hHttpOpenRequest, _
HTTP_QUERY_REQUEST_METHOD, sBuff, lBuffLen, 0) _
= 1) Then
List1.AddItem sBuff
End If"?> Dim sBuff As String * 1024
Dim lBuffLen As Long
lBuffLen = Len(sBuff)
'response headers
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_CONTENT_TYPE, sBuff, lBuffLen, 0) _ = 1) Then
List1.AddItem sBuff
End If
lBuffLen = Len(sBuff)
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_VERSION, sBuff, lBuffLen, 0) _ = 1) Then
List1.AddItem sBuff
End If
lBuffLen = Len(sBuff)
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_SERVER, sBuff, lBuffLen, 0) _ = 1) Then
List1.AddItem sBuff
End If
lBuffLen = Len(sBuff)
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_REQUEST_METHOD, sBuff, lBuffLen, 0) _ = 1) Then
List1.AddItem sBuff
End If
End If
End If
End If
End If
' Close all handles
If hInternetOpen <> 0 Then
bRet = InternetCloseHandle(hInternetOpen)
End If
If hInternetConnect <> 0 Then
bRet = InternetCloseHandle(hInternetConnect)
End If
If hHttpOpenRequest <> 0 Then
bRet = InternetCloseHandle(hHttpOpenRequest)
End If
End Sub
From the Run menu, choose Start (ALT, R, S), or press the
F5 key to run the program. Press the Command1 button and garbage will be posted
to your server.
Microsoft has confirmed this to be a bug in the Microsoft
products listed at the beginning of this article. This bug has been fixed in
Visual Studio 97 Service Pack 2.
For more information on the Visual
Studio 97 Service Pack 2, please see the following article in the Microsoft
Knowledge Base:
170365
(http://support.microsoft.com/kb/170365/EN-US/
)
: INFO: Visual Studio 97 Service Packs - What, Where, and Why
For a list of the Visual Basic 5.0 bugs that were fixed in
the Visual Studio 97 Service Pack 2, please see the following article in the
Microsoft Knowledge Base:
171554
(http://support.microsoft.com/kb/171554/EN-US/
)
: INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2
Run Visual Basic, or if Visual Basic is already running,
choose New Project from the File menu (ALT, F, N). Form1 is created by default.
From the Project menu, choose Components, and select the
Internet Transfer Control 5.0 into the project if it is not already loaded.
Place a Internet Transfer Control 5.0(Inet1) on Form1.
Place a ListBox Control(List1) on Form1.
Place a CommandButton (Command1) on Form1 and add the
following code.
Private Sub Command1_Click()
Dim strURL As String
strURL = "http://www.microsoft.com"
Inet2.Execute URL:=strURL, Operation:="HEAD"
End Sub
From the Run menu, choose Start (ALT, R, S) or press the F5
key to run the program. Press the Command1 button and garbage will be posted to
your server.
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.
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