Trevor Sullivan's Tech Room

Minding the gap between administration and development

PowerShell: ConfigMgr WMI Provider (feat. Lazy Properties)

Posted by Trevor Sullivan on 2010/09/28


What are Lazy Properties?

So if you’re a script writer, and you also use System Center Configuration Manager 2007 (ConfigMgr), you may have run into a concept called Lazy Properties. Lazy properties are certain (not all) properties on certain (not all) WMI classes, within the ConfigMgr provider namespace, that are marked with a WMI qualifier denoting the property as “lazy.” That was quite a mouthful! What exactly does this mean? Why are certain properties LAZY? Well, during the development of ConfigMgr, Microsoft realized that the enumeration of some information from the ConfigMgr provider could result in a high load on the server where the provider is installed. They introduced lazy properties as a method of providing only (what they deemed) “essential information” unless the script/software developer specifically requested more information.

How do I identify Lazy Properties?

Now that you know what lazy properties are, you are probably wondering how you’re supposed to know whether or not you have to design your code around lazy properties. This actually isn’t too hard. There are a couple different ways you’ll know that you’re dealing with a lazy property:

  • You’re not getting data back that you’d expect to when querying a ConfigMgr WMI class
  • You find a property marked with the lazy WMI qualifier using a WMI browsing tool (eg. wbemtest, SAPIEN WMI Explorer, CIM Studio, etc.)
  • Run a PowerShell script against the ConfigMgr namespace and look for property definitions with the lazy qualifier — read the last section of this article

Here is a screenshot of WbemTest (WMI utility built into Windows), browsing the class definition of root\sms\site_xyz:SMS_AuthorizationList. Instances of the SMS_AuthorizationList class represent Update List objects in ConfigMgr Software Updates. We can see that the property named “Updates” on this class is marked as lazy. This is just one example, and there are many more properties just like this one.

Ok, so how do I get values from Lazy Properties?

Getting values from lazy properties takes just a couple extra steps than normally working with WMI objects. The key thing to remember with lazy properties is that you have to get a reference to each WMI instance (aka. object) explicitly. You’re still ok to enumerate WMI instances using the SwbemServices.ExecQuery() COM interface in VBscript & PowerShell, or Get-WmiObject in PowerShell, but when you’re iterating over each instance, you must get a second, explicit reference to the WMI instance you’re wanting to work with. Let’s look at an example.

PowerShell Code – Retrieving a Lazy Property

Here is a sample script that retrieves all instances of the SMS_AuthorizationList class, that we examined above. Take note that as we iterate over each instance of SMS_AuthorizationList, we are redefining the $UpdateList variable by retrieving a direct reference to the instance. If we hadn’t done this, the Updates property that we looked at in WbemTest would appear to be empty!

# Retrieve an array of all Update List objects
$UpdateLists = Get-WmiObject -Namespace root\sms\site_lab -Class SMS_AuthorizationList

# Iterate over each Update List object in results
foreach ($UpdateList in $UpdateLists)
{
    # Using the __PATH property, obtain a direct reference to the instance
    $UpdateList = [wmi]"$($UpdateList.__PATH)"

    # Iterate over each update CI_ID in the Updates array
    foreach ($Update in $UpdateList.Updates)
    {
        # Get a reference to the update we're working with, based on its CI_ID
        $Update = Get-WmiObject -Namespace root\sms\site_lab -Query "select * from SMS_SoftwareUpdate where CI_ID = '$Update'"
        Write-Host "Update List ($($UpdateList.LocalizedDisplayName)) contains update: ",$Update.LocalizedDisplayName
    }
}

Code Results

Here is a screenshot of Quest’s free PowerGUI Script Editor running the script above, and retrieving a ConfigMgr lazy property (SMS_AuthorizationList.Updates). It’s actually doing a bit more than simply retrieving a WMI instance with its lazy properties — the lazy property (Updates) itself contains only an array of the UpdateIDs (aka. it’s CI_ID) associated to the Update List (SMS_AuthorizationList) object. We’re going one step further and cross-reference the UpdateID with the SMS_SoftwareUpdate class, so we can retrieve more information about the individual updates. This enables us to print out the friendly name of the update, as seen below in the lower-right PowerShell Console window.

What happens if I don’t retrieve lazy properties in my script?

So you’re thinking you can get off easy by just not retrieving lazy properties, right? Well, you can, but you’ll likely run into trouble. The thing is, if you make any changes to your WMI objects, and write them back to the ConfigMgr provider using the Put() method, you’ll effectively erase the values of any lazy properties on that object! It goes without saying that you need to be very careful when making any changes to your ConfigMgr objects via the provider (which is the only way you should be doing it in the first place, programatically).

If you’re simply reading information from the provider, and do not require the information contained within any lazy properties, then you are safe to read the information without performing the additional steps above.

Mega-Bonus Round: Listing All ConfigMgr Lazy Properties

Here’s a very simple PowerShell script we can use to spit out a list of all the lazy properties in the ConfigMgr namespace! Keep in mind that this could change with service pack or “R” revisions to ConfigMgr. I also would surmise that ConfigMgr vNext will introduce more changes to this list, and who knows, maybe they’ll eliminate lazy properties altogether! Just a theory, don’t quote me 🙂

PowerShell Code – Listing All ConfigMgr Lazy Properties

If you copy/paste/execute this code, after changing “lab” to your ConfigMgr site code, you should be able to get similar output to what I’ve included below for a reference. If you’re running the script from a remote management workstation, rather than on your server with the ConfigMgr provider, simply tack on the -ComputerName parameter to the Get-WmiObject cmdlet.

$WmiClassList = Get-WmiObject -List -Namespace root\sms\site_lab
$LazyList = @()

# Iterate over each WMI class in the namespace
foreach ($WmiClass in $WmiClassList)
{
    # Iterate over properties for current WMI class
    foreach ($WmiProperty in $WmiClass.Properties)
    {
        # Iterate over WMI qualifiers for current WMI property
        foreach ($WmiQualifier in $WmiProperty.Qualifiers)
        {
            # If qualifier is named "lazy", and the value is "true", then it's a lazy property
            if ($WmiQualifier.Name -eq 'lazy')
            {
                # Add class name, property name, and qualifier name to array for processing
                $LazyList += New-Object PSCustomObject -Property @{ "Class" = $WmiClass.__CLASS; "Property" = $WmiProperty.Name; "Qualifier" = $WmiQualifier.Name }
            }
        }
    }
}

# Sort array of lazy properties by WMI class name, property name
$LazyList = $LazyList | Sort-Object -Property Class,Property
# Write array of lazy properties to console
Format-Table -InputObject $LazyList -Property Class,Property,Qualifier | Out-File "All ConfigMgr Lazy Properties.txt"

ConfigMgr Lazy Property Reference

This is a reference of all ConfigMgr lazy properties, based on an installation of ConfigMgr 2007 SP2 with R3 Release Candidate installed. It’s possible that this list could change, but if you simply run the script above (change your site code from “lab), you can get a current list once again.

Class                                       Property                                    Qualifier
-----                                       --------                                    ---------
SMS_Advertisement                           AssignedSchedule                            lazy
SMS_Advertisement                           AssignedScheduleEnabled                     lazy
SMS_Advertisement                           AssignedScheduleIsGMT                       lazy
SMS_Advertisement                           ExpirationTimeEnabled                       lazy
SMS_Advertisement                           ExpirationTimeIsGMT                         lazy
SMS_Advertisement                           ISVData                                     lazy
SMS_Advertisement                           ISVDataSize                                 lazy
SMS_Advertisement                           PresentTimeEnabled                          lazy
SMS_Advertisement                           PresentTimeIsGMT                            lazy
SMS_AuthorizationList                       LocalizedInformation                        lazy
SMS_AuthorizationList                       Updates                                     lazy
SMS_BootImagePackage                        BackgroundBitmapPath                        lazy
SMS_BootImagePackage                        ContextID                                   lazy
SMS_BootImagePackage                        EnableLabShell                              lazy
SMS_BootImagePackage                        ImageDiskLayout                             lazy
SMS_BootImagePackage                        ImageIndex                                  lazy
SMS_BootImagePackage                        ImageProperty                               lazy
SMS_BootImagePackage                        ReferencedDrivers                           lazy
SMS_CategoryInstanceBase                    LocalizedInformation                        lazy
SMS_CertificateInfo                         Certificate                                 lazy
SMS_CertificateInfo                         PublicKey                                   lazy
SMS_CertificateInfo                         Thumbprint                                  Lazy
SMS_CI_CurrentComplianceStatus              ComplianceStatusDetails                     lazy
SMS_Collection                              CollectionRules                             lazy
SMS_Collection                              RefreshSchedule                             lazy
SMS_Collection                              RefreshType                                 lazy
SMS_Collection                              ReplicateToSubSites                         lazy
SMS_CollectionSettings                      CollectionVariables                         lazy
SMS_CollectionSettings                      PowerConfigs                                lazy
SMS_CollectionSettings                      ServiceWindows                              lazy
SMS_ConfigurationItem                       LocalizedEulas                              lazy
SMS_ConfigurationItem                       LocalizedInformation                        lazy
SMS_ConfigurationItemBaseClass              IsDigest                                    lazy
SMS_ConfigurationItemBaseClass              SDMPackageLocalizedData                     lazy
SMS_ConfigurationItemBaseClass              SDMPackageXML                               lazy
SMS_DeviceSettingItem                       PropList                                    lazy
SMS_DeviceSettingPackage                    DeviceSettingItemUniqueIDs                  lazy
SMS_DistributionPoint                       ISVData                                     lazy
SMS_DistributionPoint                       ISVDataSize                                 lazy
SMS_Driver                                  LocalizedEulas                              lazy
SMS_Driver                                  LocalizedInformation                        lazy
SMS_EULAContent                             EULAText                                    lazy
SMS_G_System_CollectedFile                  FileData                                    lazy
SMS_ImagePackage                            ImageDiskLayout                             lazy
SMS_ImagePackage                            ImageProperty                               lazy
SMS_MachineSettings                         MachineVariables                            lazy
SMS_ObjectContainerNode                     SearchString                                lazy
SMS_OperatingSystemInstallPackage           ImageProperty                               lazy
SMS_PackageBaseclass                        AlternateContentProviders                   lazy
SMS_PackageBaseclass                        ExtendedData                                lazy
SMS_PackageBaseclass                        ExtendedDataSize                            lazy
SMS_PackageBaseclass                        IconSize                                    lazy
SMS_PackageBaseclass                        ISVData                                     lazy
SMS_PackageBaseclass                        ISVDataSize                                 lazy
SMS_PackageBaseclass                        RefreshPkgSourceFlag                        lazy
SMS_PackageBaseclass                        RefreshSchedule                             lazy
SMS_PDF_Package                             Icon                                        lazy
SMS_PDF_Package                             IconSize                                    lazy
SMS_PDF_Package                             RequiredIconNames                           lazy
SMS_PDF_Package                             Status                                      lazy
SMS_PDF_Program                             Icon                                        lazy
SMS_PDF_Program                             IconSize                                    lazy
SMS_PendingRegistrationRecord               Certificate                                 lazy
SMS_PendingRegistrationRecord               PublicKey                                   lazy
SMS_PendingRegistrationRecord               Thumbprint                                  Lazy
SMS_Program                                 ExtendedData                                lazy
SMS_Program                                 ExtendedDataSize                            lazy
SMS_Program                                 IconSize                                    lazy
SMS_Program                                 ISVData                                     lazy
SMS_Program                                 ISVDataSize                                 lazy
SMS_Program                                 SupportedOperatingSystems                   lazy
SMS_Report                                  DrillThroughReportPath                      lazy
SMS_Report                                  ReportParams                                lazy
SMS_Report                                  SQLQuery                                    lazy
SMS_SiteControlFile                         BuildNumber                                 lazy
SMS_SiteControlFile                         FormatVersion                               lazy
SMS_SiteControlFile                         SCFData                                     lazy
SMS_SiteInstallMap                          BuildNumber                                 lazy
SMS_SiteInstallMap                          FormatVersion                               lazy
SMS_SiteInstallMap                          IMapData                                    lazy
SMS_SoftwareUpdate                          LocalizedEulas                              lazy
SMS_SoftwareUpdate                          LocalizedInformation                        lazy
SMS_SoftwareUpdateSource                    PublicKeys                                  Lazy
SMS_StateMigration                          UserNames                                   lazy
SMS_TaskSequencePackage                     BootImageID                                 lazy
SMS_TaskSequencePackage                     Category                                    lazy
SMS_TaskSequencePackage                     CustomProgressMsg                           lazy
SMS_TaskSequencePackage                     DependentProgram                            lazy
SMS_TaskSequencePackage                     References                                  lazy
SMS_TaskSequencePackage                     Reserved                                    lazy
SMS_TaskSequencePackage                     Sequence                                    lazy
SMS_TaskSequencePackage                     SupportedOperatingSystems                   lazy
SMS_TaskSequencePackage                     TaskSequenceFlags                           lazy
SMS_TaskSequencePackage                     Type                                        lazy
SMS_Template                                Data                                        lazy
SMS_UpdatesAssignment                       LegacyCollectInventory                      lazy
SMS_UpdatesAssignment                       LegacyDeploymentSchedule                    lazy
SMS_UpdatesAssignment                       LegacyDPLocality                            lazy
SMS_UpdatesAssignment                       LegacyForceReboot                           lazy
SMS_UpdatesAssignment                       LegacyInstallAllOnDeadline                  lazy
SMS_UpdatesAssignment                       LegacyInstallAllowedWindow                  lazy
SMS_UpdatesAssignment                       LegacyPostponeInstall                       lazy
SMS_UpdatesAssignment                       LegacySilentInstall                         lazy
SMS_VirtualApp                              IconSize                                    lazy
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