diff --git a/openslides/agenda/apps.py b/openslides/agenda/apps.py
index f8a3c2122..fb8ba7772 100644
--- a/openslides/agenda/apps.py
+++ b/openslides/agenda/apps.py
@@ -2,21 +2,18 @@ from typing import Any, Dict, Set
 
 from django.apps import AppConfig
 
-from ..utils.projector import register_projector_elements
-
 
 class AgendaAppConfig(AppConfig):
     name = "openslides.agenda"
     verbose_name = "OpenSlides Agenda"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from django.db.models.signals import pre_delete, post_save
         from ..core.signals import permission_change
         from ..utils.rest_api import router
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import (
             get_permission_change_data,
             listen_to_related_object_post_delete,
@@ -27,7 +24,7 @@ class AgendaAppConfig(AppConfig):
         from ..utils.access_permissions import required_user
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         post_save.connect(
diff --git a/openslides/agenda/models.py b/openslides/agenda/models.py
index 1d98dc276..89c78cce2 100644
--- a/openslides/agenda/models.py
+++ b/openslides/agenda/models.py
@@ -10,7 +10,7 @@ from django.utils import timezone
 from django.utils.translation import ugettext as _, ugettext_lazy
 
 from openslides.core.config import config
-from openslides.core.models import Countdown, Projector
+from openslides.core.models import Countdown
 from openslides.utils.autoupdate import inform_changed_data
 from openslides.utils.exceptions import OpenSlidesError
 from openslides.utils.models import RESTModelMixin
@@ -291,18 +291,6 @@ class Item(RESTModelMixin, models.Model):
     def __str__(self):
         return self.title
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete an agenda item. Ensures that a respective
-        list of speakers projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="agenda/list-of-speakers", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     @property
     def title(self):
         """
diff --git a/openslides/agenda/projector.py b/openslides/agenda/projector.py
index ffcdeb6be..83ef74f29 100644
--- a/openslides/agenda/projector.py
+++ b/openslides/agenda/projector.py
@@ -1,57 +1,89 @@
-from typing import Generator, Type
+from collections import defaultdict
+from typing import Any, Dict, List, Tuple
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import Item
+from ..utils.projector import AllData, register_projector_element
 
 
-class ItemListSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def get_tree(
+    all_data: AllData, parent_id: int = 0
+) -> List[Tuple[int, List[Tuple[int, List[Any]]]]]:
     """
-    Slide definitions for Item model.
+    Build the item tree from all_data.
 
-    This is only for item list slides.
+    Only build the tree from elements unterneath parent_id.
 
-    Set 'id' to None to get a list slide of all root items. Set 'id' to an
-    integer to get a list slide of the children of the metioned item.
-
-    Additionally set 'tree' to True to get also children of children.
+    Returns a list of two element tuples where the first element is the item title
+    and the second a List with children as two element tuples.
     """
 
-    name = "agenda/item-list"
+    # Build a dict from an item_id to all its children
+    children: Dict[int, List[int]] = defaultdict(list)
+    for item in sorted(
+        all_data["agenda/item"].values(), key=lambda item: item["weight"]
+    ):
+        if item["type"] == 1:  # only normal items
+            children[item["parent_id"] or 0].append(item["id"])
 
-    def check_data(self):
-        pk = self.config_entry.get("id")
-        if pk is not None:
-            # Children slide.
-            if not Item.objects.filter(pk=pk).exists():
-                raise ProjectorException("Item does not exist.")
+    def get_children(
+        item_ids: List[int]
+    ) -> List[Tuple[int, List[Tuple[int, List[Any]]]]]:
+        return [
+            (all_data["agenda/item"][item_id]["title"], get_children(children[item_id]))
+            for item_id in item_ids
+        ]
+
+    return get_children(children[parent_id])
 
 
-class ListOfSpeakersSlide(ProjectorElement):
+def items(config: Dict[str, Any], all_data: AllData) -> Dict[str, Any]:
     """
-    Slide definitions for Item model.
-    This is only for list of speakers slide. You have to set 'id'.
+    Item list slide.
+
+    Returns all root items or all children of an item.
     """
+    root_item_id = config.get("id") or None
+    show_tree = config.get("tree") or False
 
-    name = "agenda/list-of-speakers"
+    if show_tree:
+        items = get_tree(all_data, root_item_id or 0)
+    else:
+        items = []
+        for item in sorted(
+            all_data["agenda/item"].values(), key=lambda item: item["weight"]
+        ):
+            if item["parent_id"] == root_item_id and item["type"] == 1:
+                items.append(item["title"])
 
-    def check_data(self):
-        if not Item.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Item does not exist.")
-
-    def update_data(self):
-        return {"agenda_item_id": self.config_entry.get("id")}
+    return {"items": items}
 
 
-class CurrentListOfSpeakersSlide(ProjectorElement):
+def list_of_speakers(config: Dict[str, Any], all_data: AllData) -> Dict[str, Any]:
     """
-    Slide for the current list of speakers.
+    List of speakers slide.
+
+    Returns all usernames, that are on the list of speaker of a slide.
     """
+    item_id = config.get("id") or 0  # item_id 0 means current_list_of_speakers
 
-    name = "agenda/current-list-of-speakers"
+    # TODO: handle item_id == 0
+
+    try:
+        item = all_data["agenda/item"][item_id]
+    except KeyError:
+        return {"error": "Item {} does not exist".format(item_id)}
+
+    user_ids = []
+    for speaker in item["speakers"]:
+        user_ids.append(speaker["user"])
+    return {"user_ids": user_ids}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield ItemListSlide
-    yield ListOfSpeakersSlide
-    yield CurrentListOfSpeakersSlide
+def register_projector_elements() -> None:
+    register_projector_element("agenda/item-list", items)
+    register_projector_element("agenda/list-of-speakers", list_of_speakers)
diff --git a/openslides/assignments/apps.py b/openslides/assignments/apps.py
index 1f2ad5b95..f33e3705b 100644
--- a/openslides/assignments/apps.py
+++ b/openslides/assignments/apps.py
@@ -3,14 +3,11 @@ from typing import Any, Dict, List, Set
 from django.apps import AppConfig
 from mypy_extensions import TypedDict
 
-from ..utils.projector import register_projector_elements
-
 
 class AssignmentsAppConfig(AppConfig):
     name = "openslides.assignments"
     verbose_name = "OpenSlides Assignments"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
@@ -18,12 +15,12 @@ class AssignmentsAppConfig(AppConfig):
         from ..utils.access_permissions import required_user
         from ..utils.rest_api import router
         from . import serializers  # noqa
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import get_permission_change_data
         from .views import AssignmentViewSet, AssignmentPollViewSet
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         permission_change.connect(
diff --git a/openslides/assignments/models.py b/openslides/assignments/models.py
index 42ffb2182..4e2465b25 100644
--- a/openslides/assignments/models.py
+++ b/openslides/assignments/models.py
@@ -10,7 +10,7 @@ from django.utils.translation import ugettext as _, ugettext_noop
 
 from openslides.agenda.models import Item, Speaker
 from openslides.core.config import config
-from openslides.core.models import Projector, Tag
+from openslides.core.models import Tag
 from openslides.poll.models import (
     BaseOption,
     BasePoll,
@@ -159,18 +159,6 @@ class Assignment(RESTModelMixin, models.Model):
     def __str__(self):
         return self.title
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete an assignment. Ensures that a respective
-        assignment projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="assignments/assignment", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     @property
     def candidates(self):
         """
@@ -432,21 +420,6 @@ class AssignmentPoll(  # type: ignore
     class Meta:
         default_permissions = ()
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete an assignment poll. Ensures that a respective
-        assignment projector element (with poll, so called poll slide) is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate,
-            name="assignments/assignment",
-            id=self.assignment.pk,
-            poll=self.pk,
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     def get_assignment(self):
         return self.assignment
 
diff --git a/openslides/assignments/projector.py b/openslides/assignments/projector.py
index 507bbc1a6..ae854d11a 100644
--- a/openslides/assignments/projector.py
+++ b/openslides/assignments/projector.py
@@ -1,45 +1,23 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import Assignment, AssignmentPoll
+from ..utils.projector import register_projector_element
 
 
-class AssignmentSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def assignment(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for Assignment model.
-
-    You can send a poll id to get a poll slide.
+    Assignment slide.
     """
-
-    name = "assignments/assignment"
-
-    def check_data(self):
-        if not Assignment.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Election does not exist.")
-        poll_id = self.config_entry.get("poll")
-        if poll_id:
-            # Poll slide.
-            try:
-                poll = AssignmentPoll.objects.get(pk=poll_id)
-            except AssignmentPoll.DoesNotExist:
-                raise ProjectorException("Poll does not exist.")
-            if poll.assignment_id != self.config_entry.get("id"):
-                raise ProjectorException(
-                    "Assignment id and poll do not belong together."
-                )
-
-    def update_data(self):
-        data = None
-        try:
-            assignment = Assignment.objects.get(pk=self.config_entry.get("id"))
-        except Assignment.DoesNotExist:
-            # Assignment does not exist, so just do nothing.
-            pass
-        else:
-            data = {"agenda_item_id": assignment.agenda_item_id}
-        return data
+    poll_id = config.get("tree")  # noqa
+    return {"error": "TODO"}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield AssignmentSlide
+def register_projector_elements() -> None:
+    register_projector_element("assignments/assignment", assignment)
diff --git a/openslides/core/apps.py b/openslides/core/apps.py
index c06c660e5..50f980e9c 100644
--- a/openslides/core/apps.py
+++ b/openslides/core/apps.py
@@ -7,21 +7,16 @@ from django.apps import AppConfig
 from django.conf import settings
 from django.db.models.signals import post_migrate
 
-from ..utils.projector import register_projector_elements
-
 
 class CoreAppConfig(AppConfig):
     name = "openslides.core"
     verbose_name = "OpenSlides Core"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from .config import config
-        from ..utils.rest_api import router
-        from ..utils.cache import element_cache
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from . import serializers  # noqa
         from .signals import (
             delete_django_app_permissions,
@@ -38,15 +33,18 @@ class CoreAppConfig(AppConfig):
             ProjectorViewSet,
             TagViewSet,
         )
-        from ..utils.constants import set_constants, get_constants_from_apps
         from .websocket import (
             NotifyWebsocketClientMessage,
             ConstantsWebsocketClientMessage,
             GetElementsWebsocketClientMessage,
             AutoupdateWebsocketClientMessage,
+            ListenToProjectors,
         )
-        from ..utils.websocket import register_client_message
         from ..utils.access_permissions import required_user
+        from ..utils.cache import element_cache
+        from ..utils.constants import set_constants, get_constants_from_apps
+        from ..utils.rest_api import router
+        from ..utils.websocket import register_client_message
 
         # Collect all config variables before getting the constants.
         config.collect_config_variables_from_apps()
@@ -64,7 +62,7 @@ class CoreAppConfig(AppConfig):
             set_constants(get_constants_from_apps())
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         post_permission_creation.connect(
@@ -114,6 +112,7 @@ class CoreAppConfig(AppConfig):
         register_client_message(ConstantsWebsocketClientMessage())
         register_client_message(GetElementsWebsocketClientMessage())
         register_client_message(AutoupdateWebsocketClientMessage())
+        register_client_message(ListenToProjectors())
 
         # register required_users
         required_user.add_collection_string(
diff --git a/openslides/core/exceptions.py b/openslides/core/exceptions.py
index f01a9f275..e803a4a59 100644
--- a/openslides/core/exceptions.py
+++ b/openslides/core/exceptions.py
@@ -1,10 +1,6 @@
 from openslides.utils.exceptions import OpenSlidesError
 
 
-class ProjectorException(OpenSlidesError):
-    pass
-
-
 class TagException(OpenSlidesError):
     pass
 
diff --git a/openslides/core/models.py b/openslides/core/models.py
index 6ecd853c0..46f014b3e 100644
--- a/openslides/core/models.py
+++ b/openslides/core/models.py
@@ -7,7 +7,6 @@ from jsonfield import JSONField
 from ..utils.autoupdate import Element
 from ..utils.cache import element_cache, get_element_id
 from ..utils.models import RESTModelMixin
-from ..utils.projector import get_all_projector_elements
 from .access_permissions import (
     ChatMessageAccessPermissions,
     ConfigAccessPermissions,
@@ -17,7 +16,6 @@ from .access_permissions import (
     ProjectorMessageAccessPermissions,
     TagAccessPermissions,
 )
-from .exceptions import ProjectorException
 
 
 class ProjectorManager(models.Manager):
@@ -34,6 +32,7 @@ class ProjectorManager(models.Manager):
 
 
 class Projector(RESTModelMixin, models.Model):
+    # TODO: Fix docstring
     """
     Model for all projectors.
 
@@ -103,66 +102,6 @@ class Projector(RESTModelMixin, models.Model):
             ("can_see_frontpage", "Can see the front page"),
         )
 
-    @property
-    def elements(self):
-        """
-        Retrieve all projector elements given in the config field. For
-        every element the method check_and_update_data() is called and its
-        result is also used.
-        """
-        # Get all elements from all apps.
-        elements = get_all_projector_elements()
-
-        # Parse result
-        result = {}
-        for key, value in self.config.items():
-            # Use a copy here not to change the origin value in the config field.
-            result[key] = value.copy()
-            result[key]["uuid"] = key
-            element = elements.get(value["name"])
-            if element is None:
-                result[key]["error"] = "Projector element does not exist."
-            else:
-                try:
-                    result[key].update(
-                        element.check_and_update_data(
-                            projector_object=self, config_entry=value
-                        )
-                    )
-                except ProjectorException as e:
-                    result[key]["error"] = str(e)
-        return result
-
-    @classmethod
-    def remove_any(cls, skip_autoupdate=False, **kwargs):
-        """
-        Removes all projector elements from all projectors with matching kwargs.
-        Additional properties of active projector elements are ignored:
-
-        Example: Sending {'name': 'assignments/assignment', 'id': 1} will remove
-        also projector elements with {'name': 'assignments/assignment', 'id': 1, 'poll': 2}.
-        """
-        # Loop over all projectors.
-        for projector in cls.objects.all():
-            change_projector_config = False
-            projector_config = {}
-            # Loop over all projector elements of this projector.
-            for key, value in projector.config.items():
-                # Check if the kwargs match this element.
-                for kwarg_key, kwarg_value in kwargs.items():
-                    if not value.get(kwarg_key) == kwarg_value:
-                        # No match so the element should stay. Write it into
-                        # new config field and break the loop.
-                        projector_config[key] = value
-                        break
-                else:
-                    # All kwargs match this projector element. So mark this
-                    # projector to be changed. Do not write it into new config field.
-                    change_projector_config = True
-            if change_projector_config:
-                projector.config = projector_config
-                projector.save(skip_autoupdate=skip_autoupdate)
-
 
 class ProjectionDefault(RESTModelMixin, models.Model):
     """
@@ -275,18 +214,6 @@ class ProjectorMessage(RESTModelMixin, models.Model):
     class Meta:
         default_permissions = ()
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a projector message. Ensures that a respective
-        projector message projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="core/projector-message", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
 
 class Countdown(RESTModelMixin, models.Model):
     """
@@ -306,18 +233,6 @@ class Countdown(RESTModelMixin, models.Model):
     class Meta:
         default_permissions = ()
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a countdown. Ensures that a respective
-        countdown projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="core/countdown", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     def control(self, action, skip_autoupdate=False):
         if action not in ("start", "stop", "reset"):
             raise ValueError(
diff --git a/openslides/core/projector.py b/openslides/core/projector.py
index 3ae29f8ba..fa9b29a97 100644
--- a/openslides/core/projector.py
+++ b/openslides/core/projector.py
@@ -1,43 +1,57 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..utils.projector import ProjectorElement
-from .exceptions import ProjectorException
-from .models import Countdown, ProjectorMessage
+from ..utils.projector import register_projector_element
 
 
-class Clock(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def countdown(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Clock on the projector.
+    Countdown slide.
+
+    Returns the full_data of the countdown element.
+
+    config = {
+        name: 'core/countdown',
+        id: 5,  # Countdown ID
+    }
     """
+    countdown_id = config.get("id") or 1
 
-    name = "core/clock"
+    try:
+        return all_data["core/countdown"][countdown_id]
+    except KeyError:
+        return {"error": "Countdown {} does not exist".format(countdown_id)}
 
 
-class CountdownElement(ProjectorElement):
+def message(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Countdown slide for the projector.
+    Message slide.
+
+    Returns the full_data of the message element.
+
+    config = {
+        name: 'core/projector-message',
+        id: 5,  # ProjectorMessage ID
+    }
     """
+    message_id = config.get("id") or 1
 
-    name = "core/countdown"
-
-    def check_data(self):
-        if not Countdown.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Countdown does not exists.")
+    try:
+        return all_data["core/projector-message"][message_id]
+    except KeyError:
+        return {"error": "Message {} does not exist".format(message_id)}
 
 
-class ProjectorMessageElement(ProjectorElement):
-    """
-    Short message on the projector. Rendered as overlay.
-    """
-
-    name = "core/projector-message"
-
-    def check_data(self):
-        if not ProjectorMessage.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Message does not exists.")
-
-
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield Clock
-    yield CountdownElement
-    yield ProjectorMessageElement
+def register_projector_elements() -> None:
+    register_projector_element("core/countdown", countdown)
+    register_projector_element("core/projector-message", message)
+    # TODO: Deside if we need a clock slide
diff --git a/openslides/core/serializers.py b/openslides/core/serializers.py
index 75675a41a..aba0c4266 100644
--- a/openslides/core/serializers.py
+++ b/openslides/core/serializers.py
@@ -56,7 +56,7 @@ class ProjectorSerializer(ModelSerializer):
     Serializer for core.models.Projector objects.
     """
 
-    config = JSONSerializerField(write_only=True)
+    config = JSONSerializerField()
     projectiondefaults = ProjectionDefaultSerializer(many=True, read_only=True)
 
     class Meta:
@@ -64,7 +64,6 @@ class ProjectorSerializer(ModelSerializer):
         fields = (
             "id",
             "config",
-            "elements",
             "scale",
             "scroll",
             "name",
diff --git a/openslides/core/websocket.py b/openslides/core/websocket.py
index c8f8885ab..d779eb579 100644
--- a/openslides/core/websocket.py
+++ b/openslides/core/websocket.py
@@ -1,6 +1,7 @@
 from typing import Any
 
 from ..utils.constants import get_constants
+from ..utils.projector import get_projectot_data
 from ..utils.websocket import (
     BaseWebsocketClientMessage,
     ProtocollAsyncJsonWebsocketConsumer,
@@ -111,3 +112,51 @@ class AutoupdateWebsocketClientMessage(BaseWebsocketClientMessage):
             await consumer.channel_layer.group_discard(
                 "autoupdate", consumer.channel_name
             )
+
+
+class ListenToProjectors(BaseWebsocketClientMessage):
+    """
+    The client tells, to which projector it listens.
+
+    Therefor it sends a list of projector ids. If it sends an empty list, it does
+    not want to get any projector information.
+    """
+
+    identifier = "listenToProjectors"
+    schema = {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "titel": "Listen to projectors",
+        "description": "Listen to zero, one or more projectors..",
+        "type": "object",
+        "properties": {
+            "projector_ids": {
+                "type": "array",
+                "items": {"type": "integer"},
+                "uniqueItems": True,
+            }
+        },
+        "required": ["projector_ids"],
+    }
+
+    async def receive_content(
+        self, consumer: "ProtocollAsyncJsonWebsocketConsumer", content: Any, id: str
+    ) -> None:
+        consumer.listen_projector_ids = content["projector_ids"]
+        if consumer.listen_projector_ids:
+            # listen to projector group
+            await consumer.channel_layer.group_add("projector", consumer.channel_name)
+        else:
+            # do not listen to projector group
+            await consumer.channel_layer.group_discard(
+                "projector", consumer.channel_name
+            )
+
+        # Send projector data
+        if consumer.listen_projector_ids:
+            projector_data = await get_projectot_data(consumer.listen_projector_ids)
+            for projector_id, data in projector_data.items():
+                consumer.projector_hash[projector_id] = hash(str(data))
+
+            await consumer.send_json(
+                type="projector", content=projector_data, in_response=id
+            )
diff --git a/openslides/mediafiles/apps.py b/openslides/mediafiles/apps.py
index 6357bd8c4..252c44b36 100644
--- a/openslides/mediafiles/apps.py
+++ b/openslides/mediafiles/apps.py
@@ -2,27 +2,24 @@ from typing import Any, Dict, Set
 
 from django.apps import AppConfig
 
-from ..utils.projector import register_projector_elements
-
 
 class MediafilesAppConfig(AppConfig):
     name = "openslides.mediafiles"
     verbose_name = "OpenSlides Mediafiles"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from openslides.core.signals import permission_change
         from openslides.utils.rest_api import router
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import get_permission_change_data
         from .views import MediafileViewSet
         from . import serializers  # noqa
         from ..utils.access_permissions import required_user
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         permission_change.connect(
diff --git a/openslides/mediafiles/models.py b/openslides/mediafiles/models.py
index 9238af6b0..1e5580932 100644
--- a/openslides/mediafiles/models.py
+++ b/openslides/mediafiles/models.py
@@ -3,7 +3,6 @@ from django.db import models
 from django.utils.translation import ugettext as _
 
 from ..core.config import config
-from ..core.models import Projector
 from ..utils.autoupdate import inform_changed_data
 from ..utils.models import RESTModelMixin
 from .access_permissions import MediafileAccessPermissions
@@ -67,18 +66,6 @@ class Mediafile(RESTModelMixin, models.Model):
         inform_changed_data(self.uploader)
         return result
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a mediafile. Ensures that a respective
-        mediafile projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="mediafiles/mediafile", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     def get_filesize(self):
         """
         Transforms bytes to kilobytes or megabytes. Returns the size as string.
diff --git a/openslides/mediafiles/projector.py b/openslides/mediafiles/projector.py
index 2a6b0dee3..80683ff9f 100644
--- a/openslides/mediafiles/projector.py
+++ b/openslides/mediafiles/projector.py
@@ -1,21 +1,22 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import Mediafile
+from ..utils.projector import register_projector_element
 
 
-class MediafileSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def mediafile(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for Mediafile model.
+    Slide for Mediafile.
     """
-
-    name = "mediafiles/mediafile"
-
-    def check_data(self):
-        if not Mediafile.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("File does not exist.")
+    return {"error": "TODO"}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield MediafileSlide
+def register_projector_elements() -> None:
+    register_projector_element("mediafiles/mediafile", mediafile)
diff --git a/openslides/motions/apps.py b/openslides/motions/apps.py
index 686c920dc..833bfcd0d 100644
--- a/openslides/motions/apps.py
+++ b/openslides/motions/apps.py
@@ -3,20 +3,17 @@ from typing import Any, Dict, Set
 from django.apps import AppConfig
 from django.db.models.signals import post_migrate
 
-from ..utils.projector import register_projector_elements
-
 
 class MotionsAppConfig(AppConfig):
     name = "openslides.motions"
     verbose_name = "OpenSlides Motion"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from openslides.core.signals import permission_change
         from openslides.utils.rest_api import router
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import create_builtin_workflows, get_permission_change_data
         from . import serializers  # noqa
         from .views import (
@@ -33,7 +30,7 @@ class MotionsAppConfig(AppConfig):
         from ..utils.access_permissions import required_user
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         post_migrate.connect(
diff --git a/openslides/motions/models.py b/openslides/motions/models.py
index 3071ae61e..b5fedd80c 100644
--- a/openslides/motions/models.py
+++ b/openslides/motions/models.py
@@ -12,7 +12,7 @@ from jsonfield import JSONField
 
 from openslides.agenda.models import Item
 from openslides.core.config import config
-from openslides.core.models import Projector, Tag
+from openslides.core.models import Tag
 from openslides.mediafiles.models import Mediafile
 from openslides.poll.models import (
     BaseOption,
@@ -310,18 +310,6 @@ class Motion(RESTModelMixin, models.Model):
         if not skip_autoupdate:
             inform_changed_data(self)
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a motion. Ensures that a respective
-        motion projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="motions/motion", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     def set_identifier(self):
         """
         Sets the motion identifier automaticly according to the config value if
@@ -893,18 +881,6 @@ class MotionBlock(RESTModelMixin, models.Model):
     def __str__(self):
         return self.title
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a motion block. Ensures that a respective
-        motion block projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="motions/motion-block", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     """
     Container for runtime information for agenda app (on create or update of this instance).
     """
diff --git a/openslides/motions/projector.py b/openslides/motions/projector.py
index c01c68864..75ca6565f 100644
--- a/openslides/motions/projector.py
+++ b/openslides/motions/projector.py
@@ -1,56 +1,32 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import Motion, MotionBlock
+from ..utils.projector import register_projector_element
 
 
-class MotionSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def motion(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for Motion model.
+    Motion slide.
     """
-
-    name = "motions/motion"
-
-    def check_data(self):
-        if not Motion.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Motion does not exist.")
-
-    def update_data(self):
-        data = None
-        try:
-            motion = Motion.objects.get(pk=self.config_entry.get("id"))
-        except Motion.DoesNotExist:
-            # Motion does not exist, so just do nothing.
-            pass
-        else:
-            data = {"agenda_item_id": motion.agenda_item_id}
-        return data
+    return {"error": "TODO"}
 
 
-class MotionBlockSlide(ProjectorElement):
+def motion_block(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for a block of motions (MotionBlock model).
+    Motion slide.
     """
-
-    name = "motions/motion-block"
-
-    def check_data(self):
-        if not MotionBlock.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("MotionBlock does not exist.")
-
-    def update_data(self):
-        data = None
-        try:
-            motion_block = MotionBlock.objects.get(pk=self.config_entry.get("id"))
-        except MotionBlock.DoesNotExist:
-            # MotionBlock does not exist, so just do nothing.
-            pass
-        else:
-            data = {"agenda_item_id": motion_block.agenda_item_id}
-        return data
+    return {"error": "TODO"}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield MotionSlide
-    yield MotionBlockSlide
+def register_projector_elements() -> None:
+    register_projector_element("motion/motion", motion)
+    register_projector_element("motion/motion-block", motion_block)
diff --git a/openslides/topics/apps.py b/openslides/topics/apps.py
index f18b59684..bbe0a09cb 100644
--- a/openslides/topics/apps.py
+++ b/openslides/topics/apps.py
@@ -1,25 +1,22 @@
 from django.apps import AppConfig
 
-from ..utils.projector import register_projector_elements
-
 
 class TopicsAppConfig(AppConfig):
     name = "openslides.topics"
     verbose_name = "OpenSlides Topics"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from openslides.core.signals import permission_change
         from ..utils.rest_api import router
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import get_permission_change_data
         from .views import TopicViewSet
         from . import serializers  # noqa
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         permission_change.connect(
diff --git a/openslides/topics/models.py b/openslides/topics/models.py
index 9a977a537..84b04b443 100644
--- a/openslides/topics/models.py
+++ b/openslides/topics/models.py
@@ -4,7 +4,6 @@ from django.contrib.contenttypes.fields import GenericRelation
 from django.db import models
 
 from ..agenda.models import Item
-from ..core.models import Projector
 from ..mediafiles.models import Mediafile
 from ..utils.models import RESTModelMixin
 from .access_permissions import TopicAccessPermissions
@@ -47,18 +46,6 @@ class Topic(RESTModelMixin, models.Model):
     def __str__(self):
         return self.title
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete a topic. Ensures that a respective
-        topic projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="topics/topic", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     """
     Container for runtime information for agenda app (on create or update of this instance).
     """
diff --git a/openslides/topics/projector.py b/openslides/topics/projector.py
index 4e8c51f0e..3e39aa7ba 100644
--- a/openslides/topics/projector.py
+++ b/openslides/topics/projector.py
@@ -1,32 +1,22 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import Topic
+from ..utils.projector import register_projector_element
 
 
-class TopicSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def topic(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for topic model.
+    Topic slide.
     """
-
-    name = "topics/topic"
-
-    def check_data(self):
-        if not Topic.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("Topic does not exist.")
-
-    def update_data(self):
-        data = None
-        try:
-            topic = Topic.objects.get(pk=self.config_entry.get("id"))
-        except Topic.DoesNotExist:
-            # Topic does not exist, so just do nothing.
-            pass
-        else:
-            data = {"agenda_item_id": topic.agenda_item_id}
-        return data
+    return {"error": "TODO"}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield TopicSlide
+def register_projector_elements() -> None:
+    register_projector_element("topics/topic", topic)
diff --git a/openslides/users/apps.py b/openslides/users/apps.py
index 09b902acc..17f45ad34 100644
--- a/openslides/users/apps.py
+++ b/openslides/users/apps.py
@@ -2,26 +2,23 @@ from django.apps import AppConfig
 from django.conf import settings
 from django.contrib.auth.signals import user_logged_in
 
-from ..utils.projector import register_projector_elements
-
 
 class UsersAppConfig(AppConfig):
     name = "openslides.users"
     verbose_name = "OpenSlides Users"
     angular_site_module = True
-    angular_projector_module = True
 
     def ready(self):
         # Import all required stuff.
         from . import serializers  # noqa
         from ..core.signals import post_permission_creation, permission_change
         from ..utils.rest_api import router
-        from .projector import get_projector_elements
+        from .projector import register_projector_elements
         from .signals import create_builtin_groups_and_admin, get_permission_change_data
         from .views import GroupViewSet, PersonalNoteViewSet, UserViewSet
 
         # Define projector elements.
-        register_projector_elements(get_projector_elements())
+        register_projector_elements()
 
         # Connect signals.
         post_permission_creation.connect(
diff --git a/openslides/users/models.py b/openslides/users/models.py
index 35a3215cf..0af1fdf5a 100644
--- a/openslides/users/models.py
+++ b/openslides/users/models.py
@@ -18,7 +18,6 @@ from django.utils import timezone
 from jsonfield import JSONField
 
 from ..core.config import config
-from ..core.models import Projector
 from ..utils.auth import GROUP_ADMIN_PK
 from ..utils.models import RESTModelMixin
 from .access_permissions import (
@@ -197,18 +196,6 @@ class User(RESTModelMixin, PermissionsMixin, AbstractBaseUser):
             kwargs["skip_autoupdate"] = True
         return super().save(*args, **kwargs)
 
-    def delete(self, skip_autoupdate=False, *args, **kwargs):
-        """
-        Customized method to delete an user. Ensures that a respective
-        user projector element is disabled.
-        """
-        Projector.remove_any(
-            skip_autoupdate=skip_autoupdate, name="users/user", id=self.pk
-        )
-        return super().delete(  # type: ignore
-            skip_autoupdate=skip_autoupdate, *args, **kwargs
-        )
-
     def has_perm(self, perm):
         """
         This method is closed. Do not use it but use openslides.utils.auth.has_perm.
diff --git a/openslides/users/projector.py b/openslides/users/projector.py
index 6ae22f2b5..4dac2304a 100644
--- a/openslides/users/projector.py
+++ b/openslides/users/projector.py
@@ -1,21 +1,22 @@
-from typing import Generator, Type
+from typing import Any, Dict
 
-from ..core.exceptions import ProjectorException
-from ..utils.projector import ProjectorElement
-from .models import User
+from ..utils.projector import register_projector_element
 
 
-class UserSlide(ProjectorElement):
+# Important: All functions have to be prune. This means, that thay can only
+#            access the data, that they get as argument and do not have any
+#            side effects. They are called from an async context. So they have
+#            to be fast!
+
+
+def user(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
     """
-    Slide definitions for User model.
+    User slide.
     """
-
-    name = "users/user"
-
-    def check_data(self):
-        if not User.objects.filter(pk=self.config_entry.get("id")).exists():
-            raise ProjectorException("User does not exist.")
+    return {"error": "TODO"}
 
 
-def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
-    yield UserSlide
+def register_projector_elements() -> None:
+    register_projector_element("users/user", user)
diff --git a/openslides/utils/autoupdate.py b/openslides/utils/autoupdate.py
index 495f2e477..011301cfc 100644
--- a/openslides/utils/autoupdate.py
+++ b/openslides/utils/autoupdate.py
@@ -8,6 +8,7 @@ from django.db.models import Model
 from mypy_extensions import TypedDict
 
 from .cache import element_cache, get_element_id
+from .projector import get_projectot_data
 
 
 Element = TypedDict(
@@ -192,6 +193,13 @@ def handle_changed_elements(elements: Iterable[Element]) -> None:
             "autoupdate", {"type": "send_data", "change_id": change_id}
         )
 
+        projector_data = await get_projectot_data()
+        # Send projector
+        channel_layer = get_channel_layer()
+        await channel_layer.group_send(
+            "projector", {"type": "projector_changed", "data": projector_data}
+        )
+
     if elements:
         # Save histroy here using sync code.
         history_instances = save_history(elements)
diff --git a/openslides/utils/cache.py b/openslides/utils/cache.py
index f338656b1..d45c45e5d 100644
--- a/openslides/utils/cache.py
+++ b/openslides/utils/cache.py
@@ -154,16 +154,28 @@ class ElementCache:
 
     async def get_all_full_data(self) -> Dict[str, List[Dict[str, Any]]]:
         """
-        Returns all full_data. If it does not exist, it is created.
+        Returns all full_data.
 
         The returned value is a dict where the key is the collection_string and
         the value is a list of data.
         """
+        all_data = await self.get_all_full_data_ordered()
         out: Dict[str, List[Dict[str, Any]]] = defaultdict(list)
+        for collection_string, collection_data in all_data.items():
+            for data in collection_data.values():
+                out[collection_string].append(data)
+        return dict(out)
+
+    async def get_all_full_data_ordered(self) -> Dict[str, Dict[int, Dict[str, Any]]]:
+        """
+        Like get_all_full_data but orders the element of one collection by there
+        id.
+        """
+        out: Dict[str, Dict[int, Dict[str, Any]]] = defaultdict(dict)
         full_data = await self.cache_provider.get_all_data()
         for element_id, data in full_data.items():
-            collection_string, __ = split_element_id(element_id)
-            out[collection_string].append(json.loads(data.decode()))
+            collection_string, id = split_element_id(element_id)
+            out[collection_string][id] = json.loads(data.decode())
         return dict(out)
 
     async def get_full_data(
diff --git a/openslides/utils/consumers.py b/openslides/utils/consumers.py
index 622986692..f0366ec6d 100644
--- a/openslides/utils/consumers.py
+++ b/openslides/utils/consumers.py
@@ -15,6 +15,10 @@ class SiteConsumer(ProtocollAsyncJsonWebsocketConsumer):
 
     groups = ["site"]
 
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        self.projector_hash: Dict[int, int] = {}
+        super().__init__(*args, **kwargs)
+
     async def connect(self) -> None:
         """
         A user connects to the site.
@@ -110,3 +114,21 @@ class SiteConsumer(ProtocollAsyncJsonWebsocketConsumer):
                 all_data=False,
             ),
         )
+
+    async def projector_changed(self, event: Dict[str, Any]) -> None:
+        """
+        The projector has changed.
+        """
+        all_projector_data = event["data"]
+        projector_data: Dict[int, Dict[str, Any]] = {}
+        for projector_id in self.listen_projector_ids:
+            data = all_projector_data.get(
+                projector_id, {"error": "No data for projector {}".format(projector_id)}
+            )
+            new_hash = hash(str(data))
+            if new_hash != self.projector_hash[projector_id]:
+                projector_data[projector_id] = data
+                self.projector_hash[projector_id] = new_hash
+
+        if projector_data:
+            await self.send_json(type="projector", content=projector_data)
diff --git a/openslides/utils/projector.py b/openslides/utils/projector.py
index dfb77bf6b..f8f25b6ee 100644
--- a/openslides/utils/projector.py
+++ b/openslides/utils/projector.py
@@ -1,70 +1,69 @@
-from typing import Any, Dict, Generator, Optional, Type
+from typing import Any, Callable, Dict, List
+
+from .cache import element_cache
 
 
-class ProjectorElement:
+AllData = Dict[str, Dict[int, Dict[str, Any]]]
+ProjectorElementCallable = Callable[[Dict[str, Any], AllData], Dict[str, Any]]
+
+
+projector_elements: Dict[str, ProjectorElementCallable] = {}
+
+
+def register_projector_element(name: str, element: ProjectorElementCallable) -> None:
     """
-    Base class for an element on the projector.
-
-    Every app which wants to add projector elements has to create classes
-    subclassing from this base class with different names. The name attribute
-    has to be set.
-    """
-
-    name: Optional[str] = None
-
-    def check_and_update_data(self, projector_object: Any, config_entry: Any) -> Any:
-        """
-        Checks projector element data via self.check_data() and updates
-        them via self.update_data(). The projector object and the config
-        entry have to be given.
-        """
-        self.projector_object = projector_object
-        self.config_entry = config_entry
-        assert (
-            self.config_entry.get("name") == self.name
-        ), "To get data of a projector element, the correct config entry has to be given."
-        self.check_data()
-        return self.update_data() or {}
-
-    def check_data(self) -> None:
-        """
-        Method can be overridden to validate projector element data. This
-        may raise ProjectorException in case of an error.
-
-        Default: Does nothing.
-        """
-        pass
-
-    def update_data(self) -> Dict[Any, Any]:
-        """
-        Method can be overridden to update the projector element data
-        output. This should return a dictonary. Use this for server
-        calculated data which have to be forwared to the client.
-
-        Default: Does nothing.
-        """
-        pass
-
-
-projector_elements: Dict[str, ProjectorElement] = {}
-
-
-def register_projector_elements(
-    elements: Generator[Type[ProjectorElement], None, None]
-) -> None:
-    """
-    Registers projector elements for later use.
+    Registers a projector element.
 
     Has to be called in the app.ready method.
     """
-    for AppProjectorElement in elements:
-        element = AppProjectorElement()
-        projector_elements[element.name] = element  # type: ignore
+    projector_elements[name] = element
 
 
-def get_all_projector_elements() -> Dict[str, ProjectorElement]:
+async def get_projectot_data(
+    projector_ids: List[int] = None
+) -> Dict[int, Dict[str, Any]]:
     """
-    Returns all projector elements that where registered with
-    register_projector_elements()
+    Callculates and returns the data for one or all projectors.
     """
-    return projector_elements
+    if projector_ids is None:
+        projector_ids = []
+
+    all_data = await element_cache.get_all_full_data_ordered()
+    projector_data: Dict[int, Dict[str, Dict[str, Any]]] = {}
+
+    for projector_id, projector in all_data.get("core/projector", {}).items():
+        if projector_ids and projector_id not in projector_ids:
+            # only render the projector in question.
+            continue
+
+        projector_data[projector_id] = {}
+        if not projector["config"]:
+            projector_data[projector_id] = {
+                "error": {"error": "Projector has no config"}
+            }
+            continue
+
+        for uuid, projector_config in projector["config"].items():
+            projector_element = projector_elements.get(projector_config["name"])
+            if projector_element is None:
+                projector_data[projector_id][uuid] = {
+                    "error": "Projector element {} does not exist".format(
+                        projector_config["name"]
+                    )
+                }
+            else:
+                projector_data[projector_id][uuid] = projector_element(
+                    projector_config, all_data
+                )
+    return projector_data
+
+
+def get_config(all_data: AllData, key: str) -> Any:
+    """
+    Returns the config value from all_data.
+    """
+    from ..core.config import config
+
+    return all_data[config.get_collection_string()][config.get_key_to_id()[key]][
+        "value"
+    ]
diff --git a/tests/integration/core/test_views.py b/tests/integration/core/test_views.py
index 9e296ce10..a42c962f7 100644
--- a/tests/integration/core/test_views.py
+++ b/tests/integration/core/test_views.py
@@ -29,19 +29,7 @@ class ProjectorAPI(TestCase):
         default_projector.save()
 
         response = self.client.get(reverse("projector-detail", args=["1"]))
-        content = json.loads(response.content.decode())
         self.assertEqual(response.status_code, status.HTTP_200_OK)
-        self.assertEqual(
-            content["elements"],
-            {
-                "aae4a07b26534cfb9af4232f361dce73": {
-                    "id": topic.id,
-                    "uuid": "aae4a07b26534cfb9af4232f361dce73",
-                    "name": "topics/topic",
-                    "agenda_item_id": topic.agenda_item_id,
-                }
-            },
-        )
 
     def test_invalid_slide_on_default_projector(self):
         self.client.login(username="admin", password="admin")
@@ -60,12 +48,8 @@ class ProjectorAPI(TestCase):
             content,
             {
                 "id": 1,
-                "elements": {
-                    "fc6ef43b624043068c8e6e7a86c5a1b0": {
-                        "name": "invalid_slide",
-                        "uuid": "fc6ef43b624043068c8e6e7a86c5a1b0",
-                        "error": "Projector element does not exist.",
-                    }
+                "config": {
+                    "fc6ef43b624043068c8e6e7a86c5a1b0": {"name": "invalid_slide"}
                 },
                 "scale": 0,
                 "scroll": 0,
diff --git a/tests/integration/helpers.py b/tests/integration/helpers.py
index d739d251f..1a4537a1c 100644
--- a/tests/integration/helpers.py
+++ b/tests/integration/helpers.py
@@ -4,7 +4,9 @@ from django.db import DEFAULT_DB_ALIAS, connections
 from django.test.utils import CaptureQueriesContext
 
 from openslides.core.config import config
+from openslides.core.models import Projector
 from openslides.users.models import User
+from openslides.utils.projector import get_config, register_projector_element
 
 
 class TConfig:
@@ -33,7 +35,7 @@ class TConfig:
 
 class TUser:
     """
-    Cachable, that fills the cache with the default values of the config variables.
+    Cachable, that fills the cache with fake users.
     """
 
     def get_collection_string(self) -> str:
@@ -68,6 +70,45 @@ class TUser:
         return elements
 
 
+class TProjector:
+    """
+    Cachable, that mocks the projector.
+    """
+
+    def get_collection_string(self) -> str:
+        return Projector.get_collection_string()
+
+    def get_elements(self) -> List[Dict[str, Any]]:
+        return [
+            {"id": 1, "config": {"uid1": {"name": "test/slide1", "id": 1}}},
+            {"id": 2, "config": {"uid2": {"name": "test/slide2", "id": 1}}},
+        ]
+
+    async def restrict_elements(
+        self, user_id: int, elements: List[Dict[str, Any]]
+    ) -> List[Dict[str, Any]]:
+        return elements
+
+
+def slide1(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
+    """
+    Slide that shows the general_event_name.
+    """
+    return {"name": "slide1", "event_name": get_config(all_data, "general_event_name")}
+
+
+def slide2(
+    config: Dict[str, Any], all_data: Dict[str, Dict[int, Dict[str, Any]]]
+) -> Dict[str, Any]:
+    return {"name": "slide2"}
+
+
+register_projector_element("test/slide1", slide1)
+register_projector_element("test/slide2", slide2)
+
+
 def count_queries(func, *args, **kwargs) -> int:
     context = CaptureQueriesContext(connections[DEFAULT_DB_ALIAS])
     with context:
diff --git a/tests/integration/utils/test_consumers.py b/tests/integration/utils/test_consumers.py
index b7820be7b..5b43d1c60 100644
--- a/tests/integration/utils/test_consumers.py
+++ b/tests/integration/utils/test_consumers.py
@@ -18,7 +18,7 @@ from openslides.utils.autoupdate import (
 from openslides.utils.cache import element_cache
 
 from ...unit.utils.cache_provider import Collection1, Collection2, get_cachable_provider
-from ..helpers import TConfig, TUser
+from ..helpers import TConfig, TProjector, TUser
 
 
 @pytest.fixture(autouse=True)
@@ -31,7 +31,7 @@ async def prepare_element_cache(settings):
     await element_cache.cache_provider.clear_cache()
     orig_cachable_provider = element_cache.cachable_provider
     element_cache.cachable_provider = get_cachable_provider(
-        [Collection1(), Collection2(), TConfig(), TUser()]
+        [Collection1(), Collection2(), TConfig(), TUser(), TProjector()]
     )
     element_cache._cachables = None
     await sync_to_async(element_cache.ensure_cache)()
@@ -512,3 +512,68 @@ async def test_turn_off_autoupdate(get_communicator, set_config):
     # Change a config value
     await set_config("general_event_name", "Test Event")
     assert await communicator.receive_nothing()
+
+
+@pytest.mark.asyncio
+async def test_listen_to_projector(communicator, set_config):
+    await set_config("general_system_enable_anonymous", True)
+    await communicator.connect()
+
+    await communicator.send_json_to(
+        {
+            "type": "listenToProjectors",
+            "content": {"projector_ids": [1]},
+            "id": "test_id",
+        }
+    )
+    response = await communicator.receive_json_from()
+
+    type = response.get("type")
+    content = response.get("content")
+    assert type == "projector"
+    assert content == {"1": {"uid1": {"name": "slide1", "event_name": "OpenSlides"}}}
+
+
+@pytest.mark.asyncio
+async def test_update_projector(communicator, set_config):
+    await set_config("general_system_enable_anonymous", True)
+    await communicator.connect()
+    await communicator.send_json_to(
+        {
+            "type": "listenToProjectors",
+            "content": {"projector_ids": [1]},
+            "id": "test_id",
+        }
+    )
+    await communicator.receive_json_from()
+
+    # Change a config value
+    await set_config("general_event_name", "Test Event")
+    response = await communicator.receive_json_from()
+
+    type = response.get("type")
+    content = response.get("content")
+    assert type == "projector"
+    assert content == {"1": {"uid1": {"event_name": "Test Event", "name": "slide1"}}}
+
+
+@pytest.mark.asyncio
+async def test_update_projector_to_current_value(communicator, set_config):
+    """
+    When a value does not change, the projector should not be updated.
+    """
+    await set_config("general_system_enable_anonymous", True)
+    await communicator.connect()
+    await communicator.send_json_to(
+        {
+            "type": "listenToProjectors",
+            "content": {"projector_ids": [1]},
+            "id": "test_id",
+        }
+    )
+    await communicator.receive_json_from()
+
+    # Change a config value to current_value
+    await set_config("general_event_name", "OpenSlides")
+
+    assert await communicator.receive_nothing()
diff --git a/tests/unit/agenda/test_projector.py b/tests/unit/agenda/test_projector.py
new file mode 100644
index 000000000..2b89f048c
--- /dev/null
+++ b/tests/unit/agenda/test_projector.py
@@ -0,0 +1,117 @@
+from typing import Any, Dict
+
+import pytest
+
+from openslides.agenda import projector
+
+
+@pytest.fixture
+def all_data():
+    all_data = {
+        "agenda/item": {
+            1: {
+                "id": 1,
+                "item_number": "",
+                "title": "Item1",
+                "title_with_type": "Item1",
+                "comment": None,
+                "closed": False,
+                "type": 1,
+                "is_internal": False,
+                "is_hidden": False,
+                "duration": None,
+                "speakers": [],
+                "speaker_list_closed": False,
+                "content_object": {"collection": "topics/topic", "id": 1},
+                "weight": 10,
+                "parent_id": None,
+            },
+            2: {
+                "id": 2,
+                "item_number": "",
+                "title": "item2",
+                "title_with_type": "item2",
+                "comment": None,
+                "closed": False,
+                "type": 1,
+                "is_internal": False,
+                "is_hidden": False,
+                "duration": None,
+                "speakers": [],
+                "speaker_list_closed": False,
+                "content_object": {"collection": "topics/topic", "id": 1},
+                "weight": 20,
+                "parent_id": None,
+            },
+            # hidden item
+            3: {
+                "id": 3,
+                "item_number": "",
+                "title": "item3",
+                "title_with_type": "item3",
+                "comment": None,
+                "closed": True,
+                "type": 2,
+                "is_internal": False,
+                "is_hidden": True,
+                "duration": None,
+                "speakers": [],
+                "speaker_list_closed": False,
+                "content_object": {"collection": "topics/topic", "id": 1},
+                "weight": 30,
+                "parent_id": None,
+            },
+            # Child of item 1
+            4: {
+                "id": 4,
+                "item_number": "",
+                "title": "item4",
+                "title_with_type": "item4",
+                "comment": None,
+                "closed": True,
+                "type": 1,
+                "is_internal": False,
+                "is_hidden": False,
+                "duration": None,
+                "speakers": [],
+                "speaker_list_closed": False,
+                "content_object": {"collection": "topics/topic", "id": 1},
+                "weight": 0,
+                "parent_id": 1,
+            },
+        }
+    }
+
+    return all_data
+
+
+def test_items(all_data):
+    config: Dict[str, Any] = {}
+
+    data = projector.items(config, all_data)
+
+    assert data == {"items": ["Item1", "item2"]}
+
+
+def test_items_parent(all_data):
+    config: Dict[str, Any] = {"id": 1}
+
+    data = projector.items(config, all_data)
+
+    assert data == {"items": ["item4"]}
+
+
+def test_items_tree(all_data):
+    config: Dict[str, Any] = {"tree": True}
+
+    data = projector.items(config, all_data)
+
+    assert data == {"items": [("Item1", [("item4", [])]), ("item2", [])]}
+
+
+def test_items_tree_parent(all_data):
+    config: Dict[str, Any] = {"tree": True, "id": 1}
+
+    data = projector.items(config, all_data)
+
+    assert data == {"items": [("item4", [])]}