Microsoft KB Archive/232003

= How To Determine the Version of DCOM 95/98 Using Visual Basic =

Article ID: 232003

Article Last Modified on 7/1/2004

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APPLIES TO


 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 6.0 Learning Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 6.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition
 * Microsoft Visual Basic 6.0 Enterprise Edition

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This article was previously published under Q232003



SUMMARY
The version of DCOM95 or DCOM98 installed on a Windows 9x system may be determined by checking the registry using Visual Basic. If DCOM is installed on the system, the default value of the registry key:

HKCR\CLSID\{bdc67890-4fc0-11d0-a805-00aa006d2ea4}\InstalledVersion

will contain the version of DCOM installed on the system. The version number in the registry is stored in the format "a,b,c,d", where a, b, c, and d are numeric values. These values form the version number of the DCOM install:



MORE INFORMATION
The following steps outline this process from Visual Basic:  Start a new Visual Basic Standard EXE project. Form1 is created by default. Add a CommandButton (Command1) to Form1.  Add the following code to the General Declarations section of Form1: Option Explicit

Private Const ERROR_SUCCESS = 0&

Private Const HKEY_LOCAL_MACHINE = &H80000002 Private Const HKEY_CLASSES_ROOT = &H80000000

Private Const STANDARD_RIGHTS_ALL = &H1F0000 Private Const KEY_QUERY_VALUE = &H1 Private Const KEY_SET_VALUE = &H2 Private Const KEY_CREATE_SUB_KEY = &H4 Private Const KEY_ENUMERATE_SUB_KEYS = &H8 Private Const KEY_NOTIFY = &H10 Private Const KEY_CREATE_LINK = &H20 Private Const SYNCHRONIZE = &H100000

Private Const KEY_ALL_ACCESS = _ ((STANDARD_RIGHTS_ALL Or _ KEY_QUERY_VALUE Or _ KEY_SET_VALUE Or _ KEY_CREATE_SUB_KEY Or _ KEY_ENUMERATE_SUB_KEYS Or _ KEY_NOTIFY Or _ KEY_CREATE_LINK _ ) _   And (Not SYNCHRONIZE) _   )

Private Declare Function RegOpenKeyEx _ Lib "advapi32.dll" Alias "RegOpenKeyExA" _ (ByVal hKey As Long, _   ByVal lpSubKey As String, _    ByVal ulOptions As Long, _    ByVal samDesired As Long, _    phkResult As Long) _ As Long

Private Declare Function RegCloseKey Lib _ "advapi32.dll" _ (ByVal hKey As Long) _ As Long

Private Declare Function RegQueryValueEx Lib _ "advapi32.dll" Alias "RegQueryValueExA" _ (ByVal hKey As Long, _   ByVal lpValueName As String, _    ByVal lpReserved As Long, _    lpType As Long, _    ByVal lpData As String, _    lpcbData As Long) _ As Long ' Note that if you declare the lpData ' parameter as String, you must pass it ' By Value as is done here.

Private Declare Function GetProcAddress _ Lib "kernel32" _ (ByVal hModule As Long, _   ByVal lpProcName As String) _ As Long

Private Declare Function GetModuleHandle _ Lib "kernel32" Alias "GetModuleHandleA" _ (ByVal lpModuleName As String) _ As Long Private Function DCOMEnabled As Boolean ' We need to check two things ' 1- OLE32 supports free threading ' 2- DCOM is enabled in the registry ' See Inside COM, Rogerson, pp 276-277

DCOMEnabled = False ' First, check to see if OLE32 supports free threading. ' You need to check for the CoInitializeEx function's ' presence in OLE32. ' 1- Get a handle to the OLE32 module ' 2- Try to get a ProcAddress for CoInitializeEx

Dim OLE32ModuleHandle As Long Dim CoInitializeExProcAddress As Long OLE32ModuleHandle = GetModuleHandle("OLE32") Debug.Assert (Not OLE32ModuleHandle = 0) CoInitializeExProcAddress = GetProcAddress( _          OLE32ModuleHandle, _           "CoInitializeEx") Debug.Print "CoInitializeExProcAddress = " _ & CoInitializeExProcAddress If CoInitializeExProcAddress = 0 Then DCOMEnabled = False Exit Function End If ' Now check the registry to see if DCOM is enabled. Dim lResult As Long Dim hKey As Long

lResult = RegOpenKeyEx(HKEY_LOCAL_MACHINE, _                  "SOFTWARE\Microsoft\Ole", _                   0, _                   KEY_ALL_ACCESS, _                   hKey) Debug.Assert (lResult = ERROR_SUCCESS)

Dim rgch As String rgch = String(2, 0) Dim cbrgch As Long cbrgch = Len(rgch) lResult = RegQueryValueEx(hKey, "EnableDCOM", 0, 0&, rgch, cbrgch)

Debug.Assert (lResult = ERROR_SUCCESS)

Debug.Print "Mid$(rgch, 1) is " & Mid$(rgch, 1)

If (Mid$(rgch, 1, 1) = "Y" Or Mid$(rgch, 1, 1) = "y") Then ' DCOM is Enabled DCOMEnabled = True Else DCOMEnabled = False End If  lResult = RegCloseKey(hKey) End Function

Public Function GetDCOMVersion As String ' Check the registry key "InstalledVersion" to see which ' version of DCOM is installed.

Dim hKey As Long Dim lResult As Long

' First confirm that DCOM is installed If Not DCOMEnabled Then MsgBox "Can't check version. DCOM is not installed." Exit Function End If

' open the the proper registry key lResult = RegOpenKeyEx(HKEY_CLASSES_ROOT, _        "CLSID\{bdc67890-4fc0-11d0-a805-00aa006d2ea4}\InstalledVersion", _         0, _         KEY_ALL_ACCESS, _         hKey)

If Not lResult = ERROR_SUCCESS Then MsgBox "Could not open registry key" Exit Function End If

Dim rgch As String rgch = String(64, 0)

Dim cbrgch As Long cbrgch = Len(rgch)

lResult = RegQueryValueEx(hKey, "", 0, 0&, rgch, cbrgch)

lResult = RegCloseKey(hKey)

Dim temp As String

temp = Mid$(rgch, 1, cbrgch)

GetDCOMVersion = temp

End Function

Private Sub Command1_Click MsgBox GetDCOMVersion End Sub  Run the program and click Command1. Result: If DCOM is installed on the system, the message box will display the version number.

Notes:

The function DCOMEnabled may be used separately to determine if DCOM has been installed on a system without checking for the version.

It is not necessary to test for DCOM on Windows NT 4.0 or Windows 2000 because it is already installed. (See REFERENCES below.)

The most current version of DCOM for Windows 95 and 98 might be downloaded from:

http://www.microsoft.com/com/resources/downloads.asp

