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Making a Workflow Suspend Itself
Updated: August 29, 2012
Applies To: Windows PowerShell 3.0
One of the many benefits of running workflows is that you can suspend and resume them as needed. This is crucial to some scenarios, in which parts of a workflow might be managed by different administrators or require manual intervention.
To suspend a workflow that you are running, use the Suspend-Job cmdlet. But you can also use Suspend-Workflow activity to suspend a workflow from within the workflow.
The Suspend-Workflow activity stops workflow processing temporarily. Before suspending, Windows PowerShell Workflow takes a checkpoint so the state and data are preserved when the workflow is resumed.
To resume the workflow, the user running the workflow uses the Resume-Job cmdlet. You cannot resume a workflow from within the workflow.
After the workflow is resumed, use the Windows PowerShell Job cmdlets to manage the workflow job and get its output, even if you were running the workflow interactively before it was suspended.
Use the Get-Job cmdlet to get the workflow job. To get the output of the workflow job, use the Receive-Job cmdlet.
The Suspend-Workflow activity returns a job object that represents the suspended job, even if you did not explicitly run the workflow as a job, such as by using the AsJob parameter.
The job object that Suspend-Workflow returns includes the job ID and job state. When the Suspend-Workflow activity is successful, the resulting job state is Suspended, as shown in the following example.
Workflow Test-Suspend
{
$a = Get-Date
Suspend-Workflow
(Get-Date)- $a
}
PS C:\>Test-Suspend
Id Name PSJobTypeName State HasMoreData Location Command
-- ---- ------------- ----- ----------- -------- -------
8 Job8 PSWorkflowJob Suspended True localhost Test-Suspend
To resume the workflow job, use the Resume-Job cmdlet. The Resume-Job cmdlet returns the workflow job object immediately, even though it might not yet be resumed. To get the current state of the workflow job, use the Get-Job cmdlet, as shown in the following example.
PS C:\>Resume-Job -Name Job8 Id Name PSJobTypeName State HasMoreData Location Command -- ---- ------------- ----- ----------- -------- ------- 8 Job8 PSWorkflowJob Suspended True localhost Test-Suspend PS C:\>Get-Job -Name Job8 Id Name PSJobTypeName State HasMoreData Location Command -- ---- ------------- ----- ----------- -------- ------- 8 Job8 PSWorkflowJob Completed True localhost Test-Suspend
To get the output of a workflow job, use the Receive-Job cmdlet. The output shows that the value of the $a variable, which was defined before the workflow was suspended, is available when the workflow is resumed.
PS C:\>Get-Job -Name Job8 | Receive-Job Days : 0 Hours : 0 Minutes : 0 Seconds : 19 Milliseconds : 823 Ticks : 198230041 TotalDays : 0.000229432917824074 TotalHours : 0.00550639002777778 TotalMinutes : 0.330383401666667 TotalSeconds : 19.8230041 TotalMilliseconds : 19823.0041 PSComputerName : localhost
