Get-EventSubscriber

Get-EventSubscriber [-SubscriptionId] <int> [[-SourceIdentifier] <string>] [-Force] [<CommonParameters>]

C:\PS>$timer = New-Object Timers.Timer 

C:\PS> $timer | Get-Member -Type Event 

C:\PS> Register-ObjectEvent -inputObject $timer -EventName Elapsed -SourceIdentifier Timer.Elapsed

C:\PS> Get-EventSubscriber

C:\PS> $timer = New-Object Timers.Timer 

C:\PS> $timer | Get-Member -Type Event 

   TypeName: System.Timers.Timer 

Name     MemberType Definition 
----     ---------- ---------- 
Disposed Event      System.EventHandler Disposed(System.Object, System.EventArgs) 
Elapsed  Event      System.Timers.ElapsedEventHandler Elapsed(System.Object, System.Timers.ElapsedEventArgs)

C:\PS> Register-ObjectEvent -InputObject $timer -EventName Elapsed -SourceIdentifier Timer.Elapsed

C:\PS> Get-EventSubscriber 

SubscriptionId   : 4 
SourceObject     : System.Timers.Timer 
EventName        : Elapsed 
SourceIdentifier : Timer.Elapsed 
Action           : 
HandlerDelegate  : 
SupportEvent     : False 
ForwardEvent     : False


Description
-----------
This example uses a Get-EventSubscriber command to get the event subscriber for a timer event. 

The first command uses the New-Object cmdlet to create an instance of a timer object. It saves the new timer object in the $timer variable.

The second command uses the Get-Member cmdlet to display the events that are available for timer objects. The command uses the Type parameter of the Get-Member cmdlet with a value of Event.

The third command uses the Register-ObjectEvent cmdlet to register for the Elapsed event on the timer object.

The fourth command uses the Get-EventSubscriber cmdlet to get the event subscriber for the Elapsed event.

C:\PS>$timer  = New-Object Timers.Timer

C:\PS> $timer.Interval = 500

C:\PS> Register-ObjectEvent -inputObject $timer -eventName Elapsed -sourceIdentifier Timer.Random -Action { $random = Get-Random -Min 0 -Max 100 }

Id  Name           State      HasMoreData  Location  Command
--  ----           -----      -----------  --------  -------
3   Timer.Random   NotStarted False                  $random = Get-Random ...


C:\PS> $timer.Enabled = $true

C:\PS> $subscriber = Get-EventSubcriber -sourceIdentifer Timer.Random

C:\PS> ($subscriber.action).gettype().fullname
PSEventJob

C:\PS> $subscriber.action | format-list -property *

State         : Running
Module        : __DynamicModule_6b5cbe82-d634-41d1-ae5e-ad7fe8d57fe0
StatusMessage :
HasMoreData   : True
Location      :
Command       : $random = Get-Random -Min 0 -Max 100
JobStateInfo  : Running
Finished      : System.Threading.ManualResetEvent
InstanceId    : 88944290-133d-4b44-8752-f901bd8012e2
Id            : 1
Name          : Timer.Random
ChildJobs     : {}
...

C:\PS> & $subscriber.action.module {$random}
96

C:\PS> & $subscriber.action.module {$random}
23


Description
-----------
This example shows how to use the dynamic module in the PSEventJob object in the Action property of the event subscriber.

The first command uses the New-Object cmdlet to create a timer object. The second command sets the interval of the timer to 500 (milliseconds).

The third command uses the Register-ObjectEvent cmdlet to register the Elapsed event of the timer object. The command includes an action that handles the event. Whenever the timer interval elapses, an event is raised and the commands in the action run. In this case, the Get-Random cmdlet generates a random number between 0 and 100 and saves it in the $random variable. The source identifier of the event is Timer.Random.

When you use an Action parameter in a Register-ObjectEvent command, the command returns a PSEventJob object that represents the action. 

The fourth command enables the timer.

The fifth command uses the Get-EventSubscriber cmdlet to get the event subscriber of the Timer.Random event. It saves the event subscriber object in the $subscriber variable.

The sixth command shows that the Action property of the event subscriber object contains a PSEventJob object. In fact, it contains the same PSEventJob object that the Register-ObjectEvent command returned.

The seventh command uses the Format-List cmdlet to display all of the properties of the PSEventJob object in the Action property in a list. The result reveal that the PSEventJob object has a Module property that contains a dynamic script module that implements the action.

The remaining commands use the call operator (&) to invoke the command in the module and display the value of the $random variable. You can use the call operator to invoke any command in a module, including commands that are not exported. In this case, the commands show the random number that is being generated when the Elapsed event occurs.

For more information about modules, see about_Modules.