def load(process_id):
"""Return existing workflow instance loaded from storage."""
LOG.debug("Load a process definition from %s", process_id)
storage = Storage.instance()
pdef = storage.load("definition", process_id)
xmlelement = ET.fromstring(pdef)
assert xmlelement.tag == 'process'
parent_id = ''
if "parent" in xmlelement.attrib:
parent_id = xmlelement.attrib["parent"]
process = Process(parent_id, xmlelement, process_id, Context())
process.reset_state(json.loads(storage.load("process", process.id)))
return Workflow(process)
