CIM sessions

When we last looked at the CIM cmdlets we saw that by default they use WSMAN to access remote computers but this only works if the remote computer is running PowerShell v3 with version 3.0 of the WSMAN stack.

We can force the CIM cmdlets to use DCOM by configuring a CIM session. These are analogous to PSsessions we create when using PowerShell remoting.

CIM sessions default to WSMAN – everything with CIM defaults to WSMAN unless you are accessing the local machine

PS> $sw = New-CimSession -ComputerName webr201
PS> $sw

Id           : 1
Name         : CimSession1
InstanceId   : 91ad5f5e-d5a9-4776-9965-3c520f8bb9a0
ComputerName : webr201
Protocol     : WSMAN

Get-CimInstance -CimSession $sw -ClassName Win32_ComputerSystem

Now returns the result over the session. Using a session or using

Get-CimInstance -ClassName Win32_ComputerSystem -computername webr201

both return an object of type

Microsoft.Management.Infrastructure.CimInstance#root/cimv2/Win32_ComputerSystem

So how do we create a session using DCOM?

PS> $opt = New-CimSessionOption -Protocol DCOM
PS> $sd = New-CimSession -ComputerName server02 -SessionOption $opt
PS> $sd

Id           : 2
Name         : CimSession2
InstanceId   : 3066aa29-7062-423d-a0ab-13b29cd86013
ComputerName : server02
Protocol     : DCOM

This session is used in the same way as a WSMAN session

Get-CimInstance -CimSession $sd -ClassName Win32_ComputerSystem

and returns the same object type.

We can even mix and match CIMsessions over WSMAN and DCOM

PS> Get-CimInstance -CimSession $sw, $sd -ClassName Win32_ComputerSystem | Format-Table Name, TotalPhysicalMemory –AutoSize

Name     TotalPhysicalMemory
—-     ——————-
SERVER02         17108066304
WEBR201            536403968

The CimSession parameter takes pipeline input so we can do this

Get-CimSession | Get-CimInstance -ClassName Win32_ComputerSystem | Format-Table Name, TotalPhysicalMemory –AutoSize

which has to be a cool way to access remote machines.