A workflow instance is a running instance of a workflow
Once a workflow instance has been started, it can not be changed. If
you change the underlying
process definition, it will be versioned.
Any new workflow instance
will reflect any changes to the workflow
definition. Any old
instances currently running will reference the old
Workflow instances survive Alfresco server restarts, so all user tasks will
running if you stop and restart the server. Process and task
execution variables also survive Alfresco server restarts.