Windows Management Instrumentation (WMI) uses the
Common Information Model (CIM) to represent systems,
applications, networks, devices, and other manageable
components of the modern enterprise.
Windows Management Instrumentation (WMI) is
Microsoft’s implementation of Web-Based Enterprise
Management (WBEM), the industry standard.
Classic WMI uses DCOM to communicate with networked
devices to manage remote systems. Windows PowerShell
3.0 introduces a CIM provider model that uses WinRM
to remove the dependency on DCOM. This CIM provider
model also uses new WMI provider APIs that enable
developers to write Windows PowerShell cmdlets in
native code (C++).
Do not confuse WMI providers with Windows PowerShell
providers. Many Windows features have an
associated WMI provider that exposes their management
capabilities. To get WMI providers, run a WMI query
that gets instances of the __Provider WMI class, such
as the following query.
Get-WmiObject -Class __Provider
THREE COMPONENTS OF WMI
The following three components of WMI interact with
Windows PowerShell: Namespaces, Providers, and Classes.
WMI Namespaces organize WMI providers and WMI classes
into groups of related components. In this way, they
are similar to .NET Framework namespaces.
Namespaces are not physical locations, but are more
like logical databases. All WMI namespaces are instances
of the __Namespace system class. The default WMI
namespace is Root/CIMV2 (since Microsoft Windows 2000).
To use Windows PowerShell to get WMI namespaces in the
current session, use a command with the following format.
Get-WmiObject -Class __Namespace
To get WMI namespaces in other namespaces, use the
Namespace parameter to change the location of the search.
The following command finds WMI namespaces that reside
in the Root/Cimv2/Applications namespace.
Get-WmiObject -Class __Namespace -Namespace
WMI namespaces are hierarchical. Therefore, obtaining a
list of all namespaces on a particular system requires
performing a recursive query starting at the root
WMI Providers expose information about Windows manageable
objects. A provider retrieves data from a component,
and passes that data through WMI to a management
application, such as Windows PowerShell. Most WMI
providers are dynamic providers, which means that they
obtain the data dynamically when it is requested through
the management application.
FINDING WMI CLASSES
In a default installation of Windows 8, there are more
than 1,100 WMI classes in Root/Cimv2. With this many WMI
classes, the challenge becomes identifying the
appropriate WMI class to use to perform a specific task.
Windows PowerShell 3.0 provides two ways to find WMI
classes that are related to a specific topic.
For example,to find WMI classes in the root\CIMV2 WMI
namespace that are related to disks, you can use a
query such as the one shown here.
Get-WmiObject -List *disk*
To find WMI classes that are related to memory, you
might use a query such as the one shown here.
Get-WmiObject -List *memory*
The CIM cmdlets also provide the ability to discover
WMI classes. To do this, use the Get-CIMClass cmdlet.
The command shown here lists WMI classes related
Tab expansion works when changing WMI namespaces,
and therefore use of tab expansion makes sub-WMI
namespaces easily discoverable. In the following
example, the Get-CimClass cmdlet lists WMI
classes related to power settings. To find it,
type the root/CIMV2/ WMI namespace, and then press
the Tab key several times until the
power namespace appears. Here is the command:
Get-CimClass *power* -Namespace root/cimv2/power