PowerShell's Get-Member cmdlet doesn't report all methods

Question

notepad
$Notepad = Get-CimInstance -ClassName Win32_Process -Filter "Name = 'notepad.exe'"
Invoke-CimMethod -InputObject $Notepad -MethodName Terminate

These statements work correctly, but when I use Get-CimInstance -ClassName Win32_Process -Filter "Name = 'notepad.exe'" | get-member -force to find the Terminate method, it doesn't seem to exist.

Answer 1

The Invoke-CimMethod cmdlet invokes a method of a Common Information Model (CIM) class or CIM instance …

The Get-CimInstance cmdlet gets the Common Information Model (CIM) instances of a class from a CIM server …

Do not confuse methods of Powershell and CimClass objects:

• The Get-Member cmdlet gets the members, the properties and methods, of objects.
  Output type: [Microsoft.PowerShell.Commands.MemberDefinition]
• The Get-CimClass cmdlet gets a list of Common Information Model (CIM) classes in a specific namespace.
  Output type: [Microsoft.Management.Infrastructure.CimClass]

You are looking for something like

PS D:\PShell> (Get-CimClass -ClassName Win32_Process).CimClassMethods | 
    Format-Table -AutoSize -Wrap

Name                    ReturnType Parameters 
----                    ---------- ---------- 
Create                      UInt32 {CommandLine, CurrentDirectory,
                                    ProcessStartupInformation, ProcessId}
Terminate                   UInt32 {Reason} 
GetOwner                    UInt32 {Domain, User} 
GetOwnerSid                 UInt32 {Sid} 
SetPriority                 UInt32 {Priority} 
AttachDebugger              UInt32 {} 
GetAvailableVirtualSize     UInt32 {AvailableVirtualSize} 

Answer 2

JosefZ's answer is helpful and offers an effective solution; let me complement it with a different way of explaining the issue:

tl;dr:

To discover the methods supported by a CIM instance via an object returned by Get-CimInstance, access its .CimClass.CimClassMethods property:

PS> (Get-CimInstance Win32_Process -Filter "Name = 'notepad.exe'").CimClass.CimClassMethods

Name                    ReturnType Parameters                                                            Qualifiers
----                    ---------- ----------                                                            ----------
Create                      UInt32 {CommandLine, CurrentDirectory, ProcessStartupInformation, ProcessId} {Constructor, Implemented, MappingStrings, Privileges...}
Terminate                   UInt32 {Reason}                                                              {Destructor, Implemented, MappingStrings, Privileges...}
GetOwner                    UInt32 {Domain, User}                                                        {Implemented, MappingStrings, ValueMap}
GetOwnerSid                 UInt32 {Sid}                                                                 {Implemented, MappingStrings, ValueMap}
SetPriority                 UInt32 {Priority}                                                            {Implemented, MappingStrings, ValueMap}
AttachDebugger              UInt32 {}                                                                    {Implemented, ValueMap}
GetAvailableVirtualSize     UInt32 {AvailableVirtualSize}

To restrict the above to instance methods:

(Get-CimInstance Win32_Process -Filter "Name = 'notepad.exe'").CimClass.CimClassMethods | 
  Where-Object { -not $_.Qualifiers['Static'] }

Alternatively, pass the name of the CIM class to Get-CimClass -ClassName, as in JosefZ's answer.

---

It is reasonable to expect objects returned from cmdlets to reveal all their members when piped to Get-Member - that's how it generally works in PowerShell.
However, dealing with CIM entities (classes and instances) is a special case:

• PowerShell and its .NET-based type (class) system on the one hand, and the platform-neutral CIM standard, modeling (typically) remote computing resources on the other, are distinct worlds, with their own entities, that map imperfectly onto each other.

• CIM instances are partially mapped onto PowerShell objects of type [Microsoft.Management.Infrastructure.CimInstance], as returned by Get-CimInstance:

  • These PowerShell objects are in effect partial, read-only snapshots of the underlying CIM instances.

    • By default, the full set of properties of the underlying CIM instance is represented on the PowerShell object.
      Note: While technically writeable properties are returned as well (e.g., the State property of a Win32_Service instance), assigning to such a property seems to be ignored in practice.
    • However, no methods of the underlying CIM class are present (presumably, because methods are usually used to modify objects, and thus not needed for a read-only representation).

  • You cannot directly modify CIM instances through their local [Microsoft.Management.Infrastructure.CimInstance] representations - dedicated cmdlets are required to modify CIM instances: Invoke-CimMethod to invoke methods, and Set-CimInstance to set properties.

  • Similarly, you cannot directly discover all members of a CIM class/instance by inspecting [Microsoft.Management.Infrastructure.CimInstance] objects with Get-Member, given that they are only a partial representation of their underlying CIM instances.
    As stated at the top, you have two options:

    • Access a given [Microsoft.Management.Infrastructure.CimInstance] object's CimClass property, which PowerShell automatically adds.
    • Call Get-CimClass -ClassName <CimClassName>.
    • Both methods return a [Microsoft.Management.Infrastructure.CimClass] instance that describes the CIM class in terms of its properties and methods, among other things, but note that this introspection information is based on CIM rules.