Capturing onItemChanged event in Workflow

To catch the onItemChanged event of any Sharepoint list in a workflow, the following needs to be done:

• Add a CallExternalMethod Activity, set the interface to Microsoft.SharePoint.Workflow.IListItemService
• Set the method name to InitializeForEvents
• Bind the ItemId, ListId to ItemID and ListId in the workflow properties.
• Add a HandleExternalEvent activity and specify the following properties:
  InterfaceType to Microsoft.SharePoint.Workflow.IListItemService
  Event Name : OnItemChanged
  NOTE: The correlationToken should be the same as the correlation token specified for CallExternalMethod activity.
  Method Name. This method will be called whenever there is a change in the list item.
  
• This will capture the onItemChanged event.