--- a/cubicweb/rdf.py	Fri Feb 14 18:15:55 2020 +0100
+++ b/cubicweb/rdf.py	Fri Feb 28 17:11:01 2020 +0100
@@ -15,7 +15,8 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
-from rdflib import Namespace, ConjunctiveGraph, plugin
+from rdflib import ConjunctiveGraph, plugin
+from rdflib.namespace import Namespace, RDF, FOAF
 import rdflib_jsonld  # noqa
 
 plugin.register("jsonld", plugin.Serializer, "rdflib_jsonld.serializer", "JsonLDSerializer")
@@ -30,16 +31,16 @@
     'application/ld+json': 'json-ld',
 }
 
-namespaces = {
-    "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
-    "schema": "http://schema.org/",
+NAMESPACES = {
+    "rdf": RDF,
+    "schema": Namespace("http://schema.org/"),
+    "foaf": FOAF,
 }
 
-NS_VARS = {ns: Namespace(uri) for ns, uri in namespaces.items()}
-
 
 # dict: name of CWEType -> list of regid of adapters derived from EntityRDFAdapter
 ETYPES_ADAPTERS = {
+    "CWUser": ("rdf.foaf",),
 }
 
 
@@ -47,8 +48,8 @@
     """factory to build a ``ConjunctiveGraph`` and bind all namespaces
     """
     graph = ConjunctiveGraph()
-    for vocab, rdfns in NS_VARS.items():
-        graph.bind(vocab, rdfns)
+    for prefix, rdfns in NAMESPACES.items():
+        graph.bind(prefix, rdfns)
     return graph