SPWorkflowManager class
SharePoint 2013
Contains members that enable you to centrally control the workflow templates and instances across a site collection.
Namespace:
Microsoft.SharePoint.Workflow
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Use the SPWorkflowManager class to centrally manage and control the running instances of workflows across a site collection.
Use the SPWorkflowManager object to:
Start, run, or cancel workflows.
Return all the workflows currently running on a specific item.
Perform other workflow administration operations.
The SPWorkflowManager class has no equivalent in the user interface. Through the Microsoft SharePoint Foundation user interface, users interact with the workflows running on items on an individual basis.