--- a/sat_pubsub/backend.py	Fri Aug 16 12:48:34 2019 +0200
+++ b/sat_pubsub/backend.py	Fri Aug 16 12:53:33 2019 +0200
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #
 # Copyright (c) 2012-2019 Jérôme Poisson
@@ -64,7 +64,7 @@
 import copy
 import uuid
 
-from zope.interface import implements
+from zope.interface import implementer
 
 from twisted.application import service
 from twisted.python import components, log
@@ -123,6 +123,7 @@
                               + [copy.deepcopy(d) for d in item_data[1:]])
 
 
+@implementer(iidavoll.IBackendService)
 class BackendService(service.Service, utility.EventDispatcher):
     """
     Generic publish-subscribe backend service.
@@ -134,7 +135,6 @@
     @cvar defaultConfig: The default node configuration.
     """
 
-    implements(iidavoll.IBackendService)
 
     nodeOptions = {
             const.OPT_PERSIST_ITEMS:
@@ -201,7 +201,7 @@
         self.storage = storage
         self._callbackList = []
         self.config = config
-        self.admins = config[u'admins_jids_list']
+        self.admins = config['admins_jids_list']
 
     def isAdmin(self, entity_jid):
         """Return True if an entity is an administrator"""
@@ -255,7 +255,7 @@
 
     def _makeMetaData(self, metaData):
         options = []
-        for key, value in metaData.iteritems():
+        for key, value in metaData.items():
             if key in self.nodeOptions:
                 option = {"var": key}
                 option.update(self.nodeOptions[key])
@@ -324,7 +324,7 @@
         """
         categories = []
         try:
-            entry_elt = item_elt.elements(const.NS_ATOM, "entry").next()
+            entry_elt = next(item_elt.elements(const.NS_ATOM, "entry"))
         except StopIteration:
             return categories
 
@@ -373,7 +373,7 @@
 
         # we now remove every field which is not in data schema
         to_remove = set()
-        for item_var, item_field in item_form.fields.iteritems():
+        for item_var, item_field in item_form.fields.items():
             if item_var not in schema_form.fields:
                 to_remove.add(item_field)
 
@@ -387,7 +387,7 @@
         current publisher must correspond to each item publisher
         """
         def doCheck(item_pub_map):
-            for item_publisher in item_pub_map.itervalues():
+            for item_publisher in item_pub_map.values():
                 if item_publisher.userhost() != publisher.userhost():
                     raise error.ItemForbidden()
 
@@ -431,13 +431,13 @@
                     item["id"] = yield node.getNextId()
                     new_item = True
                     if ret_payload is None:
-                        ret_pubsub_elt = domish.Element((pubsub.NS_PUBSUB, u'pubsub'))
-                        ret_publish_elt = ret_pubsub_elt.addElement(u'publish')
-                        ret_publish_elt[u'node'] = node.nodeIdentifier
+                        ret_pubsub_elt = domish.Element((pubsub.NS_PUBSUB, 'pubsub'))
+                        ret_publish_elt = ret_pubsub_elt.addElement('publish')
+                        ret_publish_elt['node'] = node.nodeIdentifier
                         ret_payload = ret_pubsub_elt
                     ret_publish_elt = ret_payload.publish
-                    ret_item_elt = ret_publish_elt.addElement(u'item')
-                    ret_item_elt["id"] = item[u"id"]
+                    ret_item_elt = ret_publish_elt.addElement('item')
+                    ret_item_elt["id"] = item["id"]
                 else:
                     check_overwrite = True
                     new_item = False
@@ -462,9 +462,9 @@
                             # TODO: handle multiple items publishing (from several
                             #       publishers)
                             raise error.NoPublishing(
-                                u"consistent_publisher is currently only possible when "
-                                u"publishing items from a single publisher. Try to "
-                                u"publish one item at a time")
+                                "consistent_publisher is currently only possible when "
+                                "publishing items from a single publisher. Try to "
+                                "publish one item at a time")
                         # we replace requestor and new payload's publisher by original
                         # item publisher to keep publisher consistent
                         requestor = publishers.pop()
@@ -506,7 +506,7 @@
 
             notifications = [(subscriber, subscriptions_, items_data)
                              for subscriber, subscriptions_
-                             in subsBySubscriber.iteritems()]
+                             in subsBySubscriber.items()]
 
             return notifications
 
@@ -762,7 +762,7 @@
             #        if at least one other entity is owner for this node
             raise error.Forbidden("You can't change your own affiliation")
 
-        to_delete = [jid_ for jid_, affiliation in affiliations.iteritems() if affiliation == 'none']
+        to_delete = [jid_ for jid_, affiliation in affiliations.items() if affiliation == 'none']
         for jid_ in to_delete:
             del affiliations[jid_]
 
@@ -960,7 +960,7 @@
         elif access_model == const.VAL_AMODEL_WHITELIST:
             yield self.checkNodeAffiliations(node, requestor)
         else:
-            raise Exception(u"Unknown access_model")
+            raise Exception("Unknown access_model")
 
         defer.returnValue((affiliation, owner, roster, access_model))
 
@@ -1154,7 +1154,7 @@
             """
             # TODO: the behaviour should be configurable (per node ?)
             if (any((requestor.userhostJID() != publisher.userhostJID()
-                    for publisher in publishers_map.itervalues()))
+                    for publisher in publishers_map.values()))
                 and not self.isAdmin(requestor)
                ):
                 raise error.Forbidden()
@@ -1278,7 +1278,7 @@
 
     discoIdentity = disco.DiscoIdentity('pubsub',
                                         'service',
-                                        u'Salut à Toi pubsub service')
+                                        'Salut à Toi pubsub service')
 
     pubsubService = None
 
@@ -1523,7 +1523,7 @@
         return d
 
     def _mapErrors(self, failure):
-        e = failure.trap(*self._errorMap.keys())
+        e = failure.trap(*list(self._errorMap.keys()))
 
         condition, pubsubCondition, feature = self._errorMap[e]
         msg = failure.value.msg
@@ -1601,7 +1601,7 @@
 
     def _publish_errb(self, failure, request):
         if failure.type == error.NodeNotFound and self.backend.supportsAutoCreate():
-            print "Auto-creating node %s" % (request.nodeIdentifier,)
+            print("Auto-creating node %s" % (request.nodeIdentifier,))
             d = self.backend.createNode(request.nodeIdentifier,
                                         request.sender,
                                         pep=self._isPep(request),
@@ -1780,8 +1780,8 @@
 
 
 
+@implementer(iwokkel.IDisco)
 class ExtraDiscoHandler(XMPPHandler):
-    implements(iwokkel.IDisco)
     # see comment in twisted/plugins/pubsub.py
     # FIXME: upstream must be fixed so we can use custom (non pubsub#) disco features