diff --git a/IPython/parallel/controller/dictdb.py b/IPython/parallel/controller/dictdb.py
index bffcc2a..057d6ee 100644
--- a/IPython/parallel/controller/dictdb.py
+++ b/IPython/parallel/controller/dictdb.py
@@ -15,10 +15,11 @@ TaskRecords are dicts of the form::
         'header' : dict(header),
         'content': dict(content),
         'buffers': list(buffers),
-        'submitted': datetime,
+        'submitted': datetime or None,
         'started': datetime or None,
         'completed': datetime or None,
-        'resubmitted': datetime or None,
+        'received': datetime or None,
+        'resubmitted': str(uuid) or None,
         'result_header' : dict(header) or None,
         'result_content' : dict(content) or None,
         'result_buffers' : list(buffers) or None,
@@ -31,16 +32,7 @@ e.g.:
 * client's outstanding: client_uuid = uuid && completed is None
 * MIA: arrived is None (and completed is None)
 
-EngineRecords are dicts of the form::
-
-    {
-        'eid' : int(id),
-        'uuid': str(uuid)
-    }
-
-This may be extended, but is currently.
-
-We support a subset of mongodb operators::
+DictDB supports a subset of mongodb operators::
 
     $lt,$gt,$lte,$gte,$ne,$in,$nin,$all,$mod,$exists
 """
@@ -210,12 +202,19 @@ class DictDB(BaseDB):
                 before_count, before, self.size_limit, culled
             )
     
+    def _check_dates(self, rec):
+        for key in ('submitted', 'started', 'completed'):
+            value = rec.get(key, None)
+            if value is not None and not isinstance(value, datetime):
+                raise ValueError("%s must be None or datetime, not %r" % (key, value))
+    
     # public API methods:
 
     def add_record(self, msg_id, rec):
         """Add a new Task Record, by msg_id."""
         if msg_id in self._records:
             raise KeyError("Already have msg_id %r"%(msg_id))
+        self._check_dates(rec)
         self._records[msg_id] = rec
         self._add_bytes(rec)
         self._maybe_cull()
@@ -232,6 +231,7 @@ class DictDB(BaseDB):
         """Update the data in an existing record."""
         if msg_id in self._culled_ids:
             raise KeyError("Record %r has been culled for size" % msg_id)
+        self._check_dates(rec)
         _rec = self._records[msg_id]
         self._drop_bytes(_rec)
         _rec.update(rec)