Enumerating WMI Settings

Microsoft® Windows® 2000 Scripting Guide

Knowing how WMI is configured on a computer can be very useful when you are debugging scripts or troubleshooting problems with the WMI service itself. For example, many WMI scripts are written under the assumption that root\cimv2 is the default namespace on the target computer. As a result, script writers who need to access a class in root\cimv2 often fail to include the namespace in the GetObject moniker, as shown in the following code sample:

Set colServices = GetObject("winmgmts:").ExecQuery _
    ("SELECT * FROM Win32_Service")

If root\cimv2 is not the default namespace on the target computer, this script will fail. To prevent this from happening, the namespace root\cimv2 must be included in the moniker, as shown in the following code sample:

Set colServices = GetObject("winmgmts:root\cimv2").ExecQuery _
    ("SELECT * FROM Win32_Service")

If the default namespace on the target computer is different from the namespace assumed by a script, the script will fail. On top of that, the user will be presented with the somewhat misleading error message "Invalid class." In truth, the failure is not because the class is invalid but because the class cannot be found in the default namespace. This is a difficult problem to troubleshoot, because you are likely to investigate possible problems with the class rather than problems with the namespace that was (or, in this case, was not) specified.

You can use the Win32_WMISetting class to determine how WMI has been configured on a computer. Configuration details such as the default namespace or the WMI build number can be useful in troubleshooting script problems. These settings also provide important administrative information such as how, or even whether, WMI errors are logged on a computer and which WMI providers will automatically be reloaded if you need to rebuild the WMI repository.

Scripting Steps

Listing 8.10 contains a script that enumerates WMI settings on a computer. To carry out this task, the script must perform the following steps:

1. Create a variable to specify the computer name.

2. Use a GetObject call to connect to the WMI namespace root\cimv2, and set the impersonation level to "impersonate."

3. Use the ExecQuery method to query the Win32_WMISetting class.

   This query returns a collection consisting of the WMI configuration settings for the computer.

4. For each group of WMI settings in the collection, echo the value of the specified property.

   Because the autorecover MOFs are stored in an array, a For Each loop must be used to enumerate each MOF.

Listing 8.10 Enumerating WMI Settings

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strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
 & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colWMISettings = objWMIService.ExecQuery _
 ("SELECT * FROM Win32_WMISetting")
For Each objWMISetting in colWMISettings
 Wscript.Echo "Default namespace: " & _
 objWMISetting.ASPScriptDefaultNamespace
 Wscript.Echo "Backup interval: " & objWMISetting.BackupInterval
 Wscript.Echo "Last backup: " & objWMISetting.BackupLastTime
 Wscript.Echo "Build version: " & objWMISetting.BuildVersion
 Wscript.Echo "Repository directory: " & _
 objWMISetting.DatabaseDirectory
 Wscript.Echo "Enable events: " & objWMISetting.EnableEvents
 Wscript.Echo "High threshold on client objects: " & _
 objWMISetting.HighThresholdOnClientObjects
 Wscript.Echo "High threshold on events: " & _
 objWMISetting.HighThresholdOnEvents
 Wscript.Echo "Installation folder: " & _
 objWMISetting.InstallationDirectory
 Wscript.Echo "Logging folder: " & objWMISetting.LoggingDirectory
 Wscript.Echo "Logging level: " & objWMISetting.LoggingLevel
 Wscript.Echo "Low threshold on client objects: " & _
 objWMISetting.LowThresholdOnClientObjects
 Wscript.Echo "Low threshold on events: " & _
 objWMISetting.LowThresholdOnEvents
 Wscript.Echo "Maximum log file size: " & objWMISetting.MaxLogFileSize
 Wscript.Echo "Maximum wait time on client objects: " & _
 objWMISetting.MaxWaitOnClientObjects
 Wscript.Echo "Maximum wait time on events: " & _
 objWMISetting.MaxWaitOnEvents
 Wscript.Echo "MOF Self-install folder: " & _
 objWMISetting.MofSelfInstallDirectory
 For Each strMOF in objWMISetting.AutorecoverMofs
 Wscript.Echo "Autorecover MOF: " & strMOF
 Next
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