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Requesting WMI Data on a 64-bit Platform

  • Artikkeli

By default, an application or script receives data from the corresponding provider when two versions of providers exist. The 32-bit provider returns data to a 32-bit application, including all scripts, and the 64-bit provider returns data to the 64-bit compiled applications. However, an application or script can request data from the nondefault provider, if it exists, by notifying WMI through flags on method calls.

Context Flags

The __ProviderArchitecture and __RequiredArchitecture string flags have a set of values handled by WMI but not defined in SDK header or type library files. The values are placed in a context parameter to signal WMI that it should request data from the nondefault provider.

The following lists the flags and their possible values.

__ProviderArchitecture

Integer value, either 32 or 64, that specifies the 32-bit or 64-bit version.

__RequiredArchitecture

Boolean value used in addition to __ProviderArchitecture to force load the specified provider version. If the version is unavailable, then WMI returns the error 0x80041013, wbemErrProviderLoadFailure for Visual Basic and WBEM_E_PROVIDER_LOAD_FAILURE for C++. The default value for this flag when it is not specified is FALSE.

On a 64-bit system that has side-by-side versions of a provider, a 32-bit application or script automatically receives data from the 32-bit provider, unless these flags are supplied and indicate that the 64-bit provider data should be returned.

Using the Context Flags

C++ applications can use the IWbemContext interface with IWbemServices::ExecMethod to communicate the use of a nondefault provider to WMI.

In scripting and Visual Basic, you must create a SWbemNamedValueSet object containing the flags for the objWbemNamedValueSet parameter of SWbemServices.ExecMethod. For more information about setting up the parameters objects for this call, see Constructing InParameters Objects and Parsing OutParameters Objects.

You can safely run scripts and applications using the context flags in older operating systems, because WMI ignores them in systems in which they are not implemented. While 32-bit and 64-bit versions of the System Registry provider exist, note that only one version of the WMI repository exists.

Accessing the Default Registry Hive

The following series of examples use the Registry Provider, which has side-by-side 32-bit and 64-bit versions preinstalled on 64-bit operating systems. In these examples, 32-bit clients get data returned by the provider from the 32-bit node HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft. 64-bit clients get data returned by the provider from the 64-bit node HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Logging.

The scripts show how to call the methods of the Registry StdRegProv class through SWbemServices.ExecMethod to obtain data from the 32-bit registry hive.

The following script gets back data from the provider that matches the bit width of the caller, in this case 64 bits, because it is a script running under the 64-bit Windows Script Host (WSH). The script gets the value from the 64-bit registry node HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\CIMOM\Logging rather than the 32-bit node HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\WBEM\CIMOM.

strComputer = "."
Const HKLM = &h80000002
Set objReg = Getobject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" & strComputer _
    & "\root\default:stdregprov")
'Set up inParameters object
Set Inparams = objReg.Methods_("GetStringValue").Inparameters
Inparams.Hdefkey = HKLM
Inparams.Ssubkeyname = "Software\Microsoft\Wbem\CIMOM"
Inparams.Svaluename = "Logging"
set Outparams = objReg.ExecMethod_("GetStringValue", Inparams)

'Show output parameters object and the registry value HKLM\SOFTWARE\
WScript.Echo Outparams.GetObjectText_
WScript.Echo "WMI Logging is set to  " & Outparams.SValue

If the Logging value in the default hive is set to 1, then the output from the script should look something like the following:

instance of __PARAMETERS
{
    ReturnValue = 0;
    sValue = "1";
};
WMI Logging is set to 1

Example: Specifically Requesting the 32-bit Registry Hive on a 64-bit Computer

The following modified example of the default script uses the __ProviderArchitecture string flag to request access to the 32-bit registry data on a 64-bit computer. The caller is connected to the 32-bit hive irrespective of whether it is a 32- or 64-bit application.

strComputer = "."
Const HKLM = &h80000002
Set objCtx = CreateObject("WbemScripting.SWbemNamedValueSet")
objCtx.Add "__ProviderArchitecture", 32
Set objLocator = CreateObject("Wbemscripting.SWbemLocator")
Set objServices = objLocator.ConnectServer(strComputer,"root\default","","",,,,objCtx)
Set objStdRegProv = objServices.Get("StdRegProv") 

Set Inparams = objStdRegProv.Methods_("GetStringValue").Inparameters
Inparams.Hdefkey = HKLM
Inparams.Ssubkeyname = "Software\Microsoft\Wbem\CIMOM"
Inparams.Svaluename = "Logging"
set Outparams = objStdRegProv.ExecMethod_("GetStringValue", Inparams,,objCtx)

'show output parameters object and the registry value HKLM\SOFTWARE\
WScript.Echo Outparams.GetObjectText_
WScript.Echo "WMI Logging is set to  " & Outparams.SValue

Example: Forcing WMI to Access the 32-bit Registry Hive on a 64-bit Computer

The following modification of the script above by adding the __ProviderArchitecture and __RequiredArchitecture flags to the context parameter forces WMI to load the 32-bit provider and get 32-bit data. If the provider does not exist, then a provider load error occurs. The context object must be supplied in the connection to WMI by calling SWbemLocator.ConnectServer.

strComputer = "."
Const HKLM = &h80000002
Set objCtx = CreateObject("WbemScripting.SWbemNamedValueSet")
objCtx.Add "__ProviderArchitecture", 32
objCtx.Add "__RequiredArchitecture", TRUE
Set objLocator = CreateObject("Wbemscripting.SWbemLocator")
Set objServices = objLocator.ConnectServer(strComputer,"root\default","","",,,,objCtx)
Set objStdRegProv = objServices.Get("StdRegProv") 

' Use ExecMethod to call the GetStringValue method
Set Inparams = objStdRegProv.Methods_("GetStringValue").Inparameters
Inparams.Hdefkey = HKLM
Inparams.Ssubkeyname = "Software\Microsoft\Wbem\CIMOM"
Inparams.Svaluename = "Logging"
set Outparams = objStdRegProv.ExecMethod_("GetStringValue", Inparams,,objCtx)

'Show output parameters object and the registry value HKLM\SOFTWARE\
WScript.Echo Outparams.GetObjectText_
WScript.Echo "WMI Logging is set to  " & Outparams.SValue

Getting and Providing Data on a 64-bit Computer