diff --git a/communication/models.py b/communication/models.py
index c0d19a0..220d29d 100644
--- a/communication/models.py
+++ b/communication/models.py
@@ -1,60 +1,47 @@
 from django.db import models
-from django.contrib.auth.models import User
+from django.conf import settings
+from django.contrib.auth.models import Group
+from django.contrib.auth import get_user_model
+from django.contrib.contenttypes.fields import (
+    GenericForeignKey, GenericRelation
+)
+from django.contrib.contenttypes.models import ContentType
 from django.utils.translation import ugettext_lazy as _
 
+User = get_user_model()
 
-class Notifying(models.Model):
-    subscribed = models.ManyToManyField(
-        User,
-        verbose_name=_("abonnés"),
-        related_name="subscribed_to"
+
+class Subscription(models.Model):
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
+    object_id = models.PositiveIntegerField()
+    content_object = GenericForeignKey('content_type', 'object_id')
+
+
+class UserSubscription(Subscription):
+    user = models.ForeignKey(settings.AUTH_USER_MODEL)
+    is_unsub = models.BooleanField(
+        _("désinscription"),
+        default=False
     )
 
-    def get_url(self, *args, **kwargs):
-        pass
+
+class GroupSubscription(Subscription):
+    group = models.ForeignKey(Group)
 
 
-class Notification(models.Model):
-    sent_by = models.ForeignKey(
-        Notifying,
-        related_name="notifs_sent"
-    )
-    about = models.ForeignKey(
-        Notifying,
-        related_name="notifs",
-    )
-    to = models.ForeignKey(
-        User,
-        verbose_name=_("envoyée à")
-    )
-    viewed_at = models.DateTimeField(
-        _("Vue à"),
-        blank=True
-    )
-    text = models.TextField(_("corps de la notification"))
+class SubscriptionMixin(models.Model):
+    subscribed_users = GenericRelation(UserSubscription)
+    subscribed_groups = GenericRelation(GroupSubscription)
 
+    def get_unique_users(self):
+        return self.subscribed_users.filter(is_unsub=False)
 
-class Commentable(Notifying):
-    pass
+    def get_group_users(self):
+        return User.objects.filter(group__in=self.subscribed_groups.all())
 
+    def get_all_subscribers(self):
+        return (self.get_unique_users().union(self.get_group_users())
+                    .exclude(is_unsub=True))
 
-class Thread(models.Model):
-    topic = models.OneToOneField(Commentable)
-
-
-class Comment(models.Model):
-    thread = models.ForeignKey(Thread)
-    parent = models.ForeignKey(
-        'Comment',
-        related_name="replies",
-    )
-    author = models.ForeignKey(
-        User,
-        verbose_name=_("auteur"),
-        editable=False
-    )
-    at = models.DateTimeField(
-        _("date d'écriture"),
-        auto_now_add=True
-    )
-    text = models.TextField(_("corps du message"))
+    class Meta:
+        abstract = True
diff --git a/event/models.py b/event/models.py
index c1c89ce..d0e4f94 100644
--- a/event/models.py
+++ b/event/models.py
@@ -3,15 +3,10 @@ from django.utils.translation import ugettext_lazy as _
 from django.core.validators import RegexValidator
 from django.core.exceptions import FieldError
 from django.db import models
-from communication.models import Commentable, Notifying
+from communication.models import SubscriptionMixin
 
 
-class Event(Commentable):
-    commentable_model = models.OneToOneField(
-        Commentable,
-        related_name="event_model",
-        parent_link=True
-    )
+class Event(SubscriptionMixin, models.Model):
     title = models.CharField(
                     _("nom de l'évènement"),
                     max_length=200,
@@ -19,7 +14,6 @@ class Event(Commentable):
     slug = models.SlugField(
                     _('identificateur'),
                     unique=True,
-                    primary_key=True,
                     help_text=_("Seulement des lettres, des chiffres ou"
                                 "les caractères '_' ou '-'."),
                 )
@@ -36,7 +30,8 @@ class Event(Commentable):
     beginning_date = models.DateTimeField(_('date de début'))
     ending_date = models.DateTimeField(
         _('date de fin'),
-        blank=True
+        blank=True,
+        null=True,
     )
 
     class Meta:
@@ -93,7 +88,7 @@ class ActivityTag(models.Model):
         return self.name
 
 
-class ActivityTemplate(Commentable):
+class ActivityTemplate(SubscriptionMixin, models.Model):
     title = models.CharField(
                     _("nom de l'activité"),
                     max_length=200,
diff --git a/requirements.txt b/requirements.txt
index 54d9b30..41fb065 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,8 @@ Pillow
 channels
 django-bootstrap-form==3.2.1
 django-widget-tweaks
+django-notifications
+django-contrib-comments
 
 # Production specific
 daphne