Merge pull request #4469 from matrix-org/revert-4451-erikj/require_format_version

Revert "Require event format version to parse or create events"

18 files changed, 91 insertions, 253 deletions

diff --git a/changelog.d/4447.misc b/changelog.d/4447.misc
deleted file mode 100644
index 43f8963614..0000000000
--- a/changelog.d/4447.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add infrastructure to support different event formats
diff --git a/changelog.d/4451.misc b/changelog.d/4451.misc
deleted file mode 100644
index 43f8963614..0000000000
--- a/changelog.d/4451.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add infrastructure to support different event formats
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index c3e6caf597..888296933b 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -18,11 +18,7 @@ from distutils.util import strtobool
 
 import six
 
-from synapse.api.constants import (
-    KNOWN_EVENT_FORMAT_VERSIONS,
-    KNOWN_ROOM_VERSIONS,
-    EventFormatVersions,
-)
+from synapse.api.constants import EventFormatVersions
 from synapse.util.caches import intern_dict
 from synapse.util.frozenutils import freeze
 
@@ -244,36 +240,3 @@ class FrozenEvent(EventBase):
             self.get("type", None),
             self.get("state_key", None),
         )
-
-
-def room_version_to_event_format(room_version):
-    """Converts a room version string to the event format
-
-    Args:
-        room_version (str)
-
-    Returns:
-        int
-    """
-    if room_version not in KNOWN_ROOM_VERSIONS:
-        raise
-
-    return EventFormatVersions.V1
-
-
-def event_type_from_format_version(format_version):
-    """Returns the python type to use to construct an Event object for the
-    given event format version.
-
-    Args:
-        format_version (int): The event format version
-
-    Returns:
-        type: A type that can be initialized as per the initializer of
-        `FrozenEvent`
-    """
-    if format_version not in KNOWN_EVENT_FORMAT_VERSIONS:
-        raise Exception(
-            "No event format %r" % (format_version,)
-        )
-    return FrozenEvent
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 7e63371095..e662eaef10 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -15,39 +15,12 @@
 
 import copy
 
-from synapse.api.constants import RoomVersions
 from synapse.types import EventID
 from synapse.util.stringutils import random_string
 
 from . import EventBase, FrozenEvent, _event_dict_property
 
 
-def get_event_builder(room_version, key_values={}, internal_metadata_dict={}):
-    """Generate an event builder appropriate for the given room version
-
-    Args:
-        room_version (str): Version of the room that we're creating an
-            event builder for
-        key_values (dict): Fields used as the basis of the new event
-        internal_metadata_dict (dict): Used to create the `_EventInternalMetadata`
-            object.
-
-    Returns:
-        EventBuilder
-    """
-    if room_version in {
-        RoomVersions.V1,
-        RoomVersions.V2,
-        RoomVersions.VDH_TEST,
-        RoomVersions.STATE_V2_TEST,
-    }:
-        return EventBuilder(key_values, internal_metadata_dict)
-    else:
-        raise Exception(
-            "No event format defined for version %r" % (room_version,)
-        )
-
-
 class EventBuilder(EventBase):
     def __init__(self, key_values={}, internal_metadata_dict={}):
         signatures = copy.deepcopy(key_values.pop("signatures", {}))
@@ -85,29 +58,7 @@ class EventBuilderFactory(object):
 
         return e_id.to_string()
 
-    def new(self, room_version, key_values={}):
-        """Generate an event builder appropriate for the given room version
-
-        Args:
-            room_version (str): Version of the room that we're creating an
-                event builder for
-            key_values (dict): Fields used as the basis of the new event
-
-        Returns:
-            EventBuilder
-        """
-
-        # There's currently only the one event version defined
-        if room_version not in {
-            RoomVersions.V1,
-            RoomVersions.V2,
-            RoomVersions.VDH_TEST,
-            RoomVersions.STATE_V2_TEST,
-        }:
-            raise Exception(
-                "No event format defined for version %r" % (room_version,)
-            )
-
+    def new(self, key_values={}):
         key_values["event_id"] = self.create_event_id()
 
         time_now = int(self.clock.time_msec())
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 5c31e5f85f..d749bfdd3a 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -23,7 +23,7 @@ from twisted.internet.defer import DeferredList
 from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
 from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.event_signing import check_event_content_hash
-from synapse.events import event_type_from_format_version
+from synapse.events import FrozenEvent
 from synapse.events.utils import prune_event
 from synapse.http.servlet import assert_params_in_dict
 from synapse.types import get_domain_from_id
@@ -302,12 +302,11 @@ def _is_invite_via_3pid(event):
     )
 
 
-def event_from_pdu_json(pdu_json, event_format_version, outlier=False):
+def event_from_pdu_json(pdu_json, outlier=False):
     """Construct a FrozenEvent from an event json received over federation
 
     Args:
         pdu_json (object): pdu as received over federation
-        event_format_version (int): The event format version
         outlier (bool): True to mark this event as an outlier
 
     Returns:
@@ -331,8 +330,8 @@ def event_from_pdu_json(pdu_json, event_format_version, outlier=False):
     elif depth > MAX_DEPTH:
         raise SynapseError(400, "Depth too large", Codes.BAD_JSON)
 
-    event = event_type_from_format_version(event_format_version)(
-        pdu_json,
+    event = FrozenEvent(
+        pdu_json
     )
 
     event.internal_metadata.outlier = outlier
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 4b25f891ca..777deabdf7 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -38,7 +38,6 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.crypto.event_signing import add_hashes_and_signatures
-from synapse.events import room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.util import logcontext, unwrapFirstError
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -170,13 +169,13 @@ class FederationClient(FederationBase):
 
     @defer.inlineCallbacks
     @log_function
-    def backfill(self, dest, room_id, limit, extremities):
+    def backfill(self, dest, context, limit, extremities):
         """Requests some more historic PDUs for the given context from the
         given destination server.
 
         Args:
             dest (str): The remote home server to ask.
-            room_id (str): The room_id to backfill.
+            context (str): The context to backfill.
             limit (int): The maximum number of PDUs to return.
             extremities (list): List of PDU id and origins of the first pdus
                 we have seen from the context
@@ -191,15 +190,12 @@ class FederationClient(FederationBase):
             return
 
         transaction_data = yield self.transport_layer.backfill(
-            dest, room_id, extremities, limit)
+            dest, context, extremities, limit)
 
         logger.debug("backfill transaction_data=%s", repr(transaction_data))
 
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-
         pdus = [
-            event_from_pdu_json(p, format_ver, outlier=False)
+            event_from_pdu_json(p, outlier=False)
             for p in transaction_data["pdus"]
         ]
 
@@ -243,8 +239,6 @@ class FederationClient(FederationBase):
 
         pdu_attempts = self.pdu_destination_tried.setdefault(event_id, {})
 
-        format_ver = room_version_to_event_format(room_version)
-
         signed_pdu = None
         for destination in destinations:
             now = self._clock.time_msec()
@@ -260,7 +254,7 @@ class FederationClient(FederationBase):
                 logger.debug("transaction_data %r", transaction_data)
 
                 pdu_list = [
-                    event_from_pdu_json(p, format_ver, outlier=outlier)
+                    event_from_pdu_json(p, outlier=outlier)
                     for p in transaction_data["pdus"]
                 ]
 
@@ -354,16 +348,12 @@ class FederationClient(FederationBase):
             destination, room_id, event_id=event_id,
         )
 
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-
         pdus = [
-            event_from_pdu_json(p, format_ver, outlier=True)
-            for p in result["pdus"]
+            event_from_pdu_json(p, outlier=True) for p in result["pdus"]
         ]
 
         auth_chain = [
-            event_from_pdu_json(p, format_ver, outlier=True)
+            event_from_pdu_json(p, outlier=True)
             for p in result.get("auth_chain", [])
         ]
 
@@ -371,6 +361,8 @@ class FederationClient(FederationBase):
             ev.event_id for ev in itertools.chain(pdus, auth_chain)
         ])
 
+        room_version = yield self.store.get_room_version(room_id)
+
         signed_pdus = yield self._check_sigs_and_hash_and_fetch(
             destination,
             [p for p in pdus if p.event_id not in seen_events],
@@ -469,14 +461,13 @@ class FederationClient(FederationBase):
             destination, room_id, event_id,
         )
 
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-
         auth_chain = [
-            event_from_pdu_json(p, format_ver, outlier=True)
+            event_from_pdu_json(p, outlier=True)
             for p in res["auth_chain"]
         ]
 
+        room_version = yield self.store.get_room_version(room_id)
+
         signed_auth = yield self._check_sigs_and_hash_and_fetch(
             destination, auth_chain,
             outlier=True, room_version=room_version,
@@ -566,9 +557,9 @@ class FederationClient(FederationBase):
             params (dict[str, str|Iterable[str]]): Query parameters to include in the
                 request.
         Return:
-            Deferred[tuple[str, FrozenEvent, int]]: resolves to a tuple of
-            `(origin, event, event_format)` where origin is the remote
-            homeserver which generated the event.
+            Deferred[tuple[str, FrozenEvent]]: resolves to a tuple of `origin`
+            and event where origin is the remote homeserver which generated
+            the event.
 
             Fails with a ``SynapseError`` if the chosen remote server
             returns a 300/400 code.
@@ -588,11 +579,6 @@ class FederationClient(FederationBase):
                 destination, room_id, user_id, membership, params,
             )
 
-            # Note: If not supplied, the room version may be either v1 or v2,
-            # however either way the event format version will be v1.
-            room_version = ret.get("room_version", RoomVersions.V1)
-            event_format = room_version_to_event_format(room_version)
-
             pdu_dict = ret.get("event", None)
             if not isinstance(pdu_dict, dict):
                 raise InvalidResponseError("Bad 'event' field in response")
@@ -612,7 +598,7 @@ class FederationClient(FederationBase):
             pdu_dict.pop("origin_server_ts", None)
             pdu_dict.pop("unsigned", None)
 
-            builder = self.event_builder_factory.new(room_version, pdu_dict)
+            builder = self.event_builder_factory.new(pdu_dict)
             add_hashes_and_signatures(
                 builder,
                 self.hs.hostname,
@@ -621,14 +607,14 @@ class FederationClient(FederationBase):
             ev = builder.build()
 
             defer.returnValue(
-                (destination, ev, event_format)
+                (destination, ev)
             )
 
         return self._try_destination_list(
             "make_" + membership, destinations, send_request,
         )
 
-    def send_join(self, destinations, pdu, event_format_version):
+    def send_join(self, destinations, pdu):
         """Sends a join event to one of a list of homeservers.
 
         Doing so will cause the remote server to add the event to the graph,
@@ -638,7 +624,6 @@ class FederationClient(FederationBase):
             destinations (str): Candidate homeservers which are probably
                 participating in the room.
             pdu (BaseEvent): event to be sent
-            event_format_version (int): The event format version
 
         Return:
             Deferred: resolves to a dict with members ``origin`` (a string
@@ -684,12 +669,12 @@ class FederationClient(FederationBase):
             logger.debug("Got content: %s", content)
 
             state = [
-                event_from_pdu_json(p, event_format_version, outlier=True)
+                event_from_pdu_json(p, outlier=True)
                 for p in content.get("state", [])
             ]
 
             auth_chain = [
-                event_from_pdu_json(p, event_format_version, outlier=True)
+                event_from_pdu_json(p, outlier=True)
                 for p in content.get("auth_chain", [])
             ]
 
@@ -767,10 +752,7 @@ class FederationClient(FederationBase):
 
         logger.debug("Got response to send_invite: %s", pdu_dict)
 
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-
-        pdu = event_from_pdu_json(pdu_dict, format_ver)
+        pdu = event_from_pdu_json(pdu_dict)
 
         # Check signatures are correct.
         pdu = yield self._check_sigs_and_hash(pdu)
@@ -848,14 +830,13 @@ class FederationClient(FederationBase):
             content=send_content,
         )
 
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-
         auth_chain = [
-            event_from_pdu_json(e, format_ver)
+            event_from_pdu_json(e)
             for e in content["auth_chain"]
         ]
 
+        room_version = yield self.store.get_room_version(room_id)
+
         signed_auth = yield self._check_sigs_and_hash_and_fetch(
             destination, auth_chain, outlier=True, room_version=room_version,
         )
@@ -899,14 +880,13 @@ class FederationClient(FederationBase):
                 timeout=timeout,
             )
 
-            room_version = yield self.store.get_room_version(room_id)
-            format_ver = room_version_to_event_format(room_version)
-
             events = [
-                event_from_pdu_json(e, format_ver)
+                event_from_pdu_json(e)
                 for e in content.get("events", [])
             ]
 
+            room_version = yield self.store.get_room_version(room_id)
+
             signed_events = yield self._check_sigs_and_hash_and_fetch(
                 destination, events, outlier=False, room_version=room_version,
             )
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 4aa04b9588..cb729c69ea 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -34,7 +34,6 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.crypto.event_signing import compute_event_signature
-from synapse.events import room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
@@ -179,13 +178,14 @@ class FederationServer(FederationBase):
                 continue
 
             try:
-                room_version = yield self.store.get_room_version(room_id)
-                format_ver = room_version_to_event_format(room_version)
+                # In future we will actually use the room version to parse the
+                # PDU into an event.
+                yield self.store.get_room_version(room_id)
             except NotFoundError:
                 logger.info("Ignoring PDU for unknown room_id: %s", room_id)
                 continue
 
-            event = event_from_pdu_json(p, format_ver)
+            event = event_from_pdu_json(p)
             pdus_by_room.setdefault(room_id, []).append(event)
 
         pdu_results = {}
@@ -370,9 +370,7 @@ class FederationServer(FederationBase):
 
     @defer.inlineCallbacks
     def on_invite_request(self, origin, content, room_version):
-        format_ver = room_version_to_event_format(room_version)
-
-        pdu = event_from_pdu_json(content, format_ver)
+        pdu = event_from_pdu_json(content)
         origin_host, _ = parse_server_name(origin)
         yield self.check_server_matches_acl(origin_host, pdu.room_id)
         ret_pdu = yield self.handler.on_invite_request(origin, pdu)
@@ -380,12 +378,9 @@ class FederationServer(FederationBase):
         defer.returnValue({"event": ret_pdu.get_pdu_json(time_now)})
 
     @defer.inlineCallbacks
-    def on_send_join_request(self, origin, content, room_id):
+    def on_send_join_request(self, origin, content):
         logger.debug("on_send_join_request: content: %s", content)
-
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-        pdu = event_from_pdu_json(content, format_ver)
+        pdu = event_from_pdu_json(content)
 
         origin_host, _ = parse_server_name(origin)
         yield self.check_server_matches_acl(origin_host, pdu.room_id)
@@ -405,22 +400,13 @@ class FederationServer(FederationBase):
         origin_host, _ = parse_server_name(origin)
         yield self.check_server_matches_acl(origin_host, room_id)
         pdu = yield self.handler.on_make_leave_request(room_id, user_id)
-
-        room_version = yield self.store.get_room_version(room_id)
-
         time_now = self._clock.time_msec()
-        defer.returnValue({
-            "event": pdu.get_pdu_json(time_now),
-            "room_version": room_version,
-        })
+        defer.returnValue({"event": pdu.get_pdu_json(time_now)})
 
     @defer.inlineCallbacks
-    def on_send_leave_request(self, origin, content, room_id):
+    def on_send_leave_request(self, origin, content):
         logger.debug("on_send_leave_request: content: %s", content)
-
-        room_version = yield self.store.get_room_version(room_id)
-        format_ver = room_version_to_event_format(room_version)
-        pdu = event_from_pdu_json(content, format_ver)
+        pdu = event_from_pdu_json(content)
 
         origin_host, _ = parse_server_name(origin)
         yield self.check_server_matches_acl(origin_host, pdu.room_id)
@@ -466,14 +452,13 @@ class FederationServer(FederationBase):
             origin_host, _ = parse_server_name(origin)
             yield self.check_server_matches_acl(origin_host, room_id)
 
-            room_version = yield self.store.get_room_version(room_id)
-            format_ver = room_version_to_event_format(room_version)
-
             auth_chain = [
-                event_from_pdu_json(e, format_ver)
+                event_from_pdu_json(e)
                 for e in content["auth_chain"]
             ]
 
+            room_version = yield self.store.get_room_version(room_id)
+
             signed_auth = yield self._check_sigs_and_hash_and_fetch(
                 origin, auth_chain, outlier=True, room_version=room_version,
             )
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 67ae0212c3..4557a9e66e 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -469,7 +469,7 @@ class FederationSendLeaveServlet(BaseFederationServlet):
 
     @defer.inlineCallbacks
     def on_PUT(self, origin, content, query, room_id, event_id):
-        content = yield self.handler.on_send_leave_request(origin, content, room_id)
+        content = yield self.handler.on_send_leave_request(origin, content)
         defer.returnValue((200, content))
 
 
@@ -487,7 +487,7 @@ class FederationSendJoinServlet(BaseFederationServlet):
     def on_PUT(self, origin, content, query, context, event_id):
         # TODO(paul): assert that context/event_id parsed from path actually
         #   match those given in content
-        content = yield self.handler.on_send_join_request(origin, content, context)
+        content = yield self.handler.on_send_join_request(origin, content)
         defer.returnValue((200, content))
 
 
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index a4b771049c..453d393ce1 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1061,7 +1061,7 @@ class FederationHandler(BaseHandler):
         """
         logger.debug("Joining %s to %s", joinee, room_id)
 
-        origin, event, event_format_version = yield self._make_and_verify_event(
+        origin, event = yield self._make_and_verify_event(
             target_hosts,
             room_id,
             joinee,
@@ -1091,9 +1091,7 @@ class FederationHandler(BaseHandler):
                 target_hosts.insert(0, origin)
             except ValueError:
                 pass
-            ret = yield self.federation_client.send_join(
-                target_hosts, event, event_format_version,
-            )
+            ret = yield self.federation_client.send_join(target_hosts, event)
 
             origin = ret["origin"]
             state = ret["state"]
@@ -1166,18 +1164,13 @@ class FederationHandler(BaseHandler):
         """
         event_content = {"membership": Membership.JOIN}
 
-        room_version = yield self.store.get_room_version(room_id)
-
-        builder = self.event_builder_factory.new(
-            room_version,
-            {
-                "type": EventTypes.Member,
-                "content": event_content,
-                "room_id": room_id,
-                "sender": user_id,
-                "state_key": user_id,
-            }
-        )
+        builder = self.event_builder_factory.new({
+            "type": EventTypes.Member,
+            "content": event_content,
+            "room_id": room_id,
+            "sender": user_id,
+            "state_key": user_id,
+        })
 
         try:
             event, context = yield self.event_creation_handler.create_new_client_event(
@@ -1311,7 +1304,7 @@ class FederationHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def do_remotely_reject_invite(self, target_hosts, room_id, user_id):
-        origin, event, event_format_version = yield self._make_and_verify_event(
+        origin, event = yield self._make_and_verify_event(
             target_hosts,
             room_id,
             user_id,
@@ -1343,7 +1336,7 @@ class FederationHandler(BaseHandler):
     @defer.inlineCallbacks
     def _make_and_verify_event(self, target_hosts, room_id, user_id, membership,
                                content={}, params=None):
-        origin, event, format_ver = yield self.federation_client.make_membership_event(
+        origin, pdu = yield self.federation_client.make_membership_event(
             target_hosts,
             room_id,
             user_id,
@@ -1352,7 +1345,9 @@ class FederationHandler(BaseHandler):
             params=params,
         )
 
-        logger.debug("Got response to make_%s: %s", membership, event)
+        logger.debug("Got response to make_%s: %s", membership, pdu)
+
+        event = pdu
 
         # We should assert some things.
         # FIXME: Do this in a nicer way
@@ -1360,7 +1355,7 @@ class FederationHandler(BaseHandler):
         assert(event.user_id == user_id)
         assert(event.state_key == user_id)
         assert(event.room_id == room_id)
-        defer.returnValue((origin, event, format_ver))
+        defer.returnValue((origin, event))
 
     @defer.inlineCallbacks
     @log_function
@@ -1369,17 +1364,13 @@ class FederationHandler(BaseHandler):
         leave event for the room and return that. We do *not* persist or
         process it until the other server has signed it and sent it back.
         """
-        room_version = yield self.store.get_room_version(room_id)
-        builder = self.event_builder_factory.new(
-            room_version,
-            {
-                "type": EventTypes.Member,
-                "content": {"membership": Membership.LEAVE},
-                "room_id": room_id,
-                "sender": user_id,
-                "state_key": user_id,
-            }
-        )
+        builder = self.event_builder_factory.new({
+            "type": EventTypes.Member,
+            "content": {"membership": Membership.LEAVE},
+            "room_id": room_id,
+            "sender": user_id,
+            "state_key": user_id,
+        })
 
         event, context = yield self.event_creation_handler.create_new_client_event(
             builder=builder,
@@ -2275,16 +2266,14 @@ class FederationHandler(BaseHandler):
         }
 
         if (yield self.auth.check_host_in_room(room_id, self.hs.hostname)):
-            room_version = yield self.store.get_room_version(room_id)
-            builder = self.event_builder_factory.new(room_version, event_dict)
-
+            builder = self.event_builder_factory.new(event_dict)
             EventValidator().validate_new(builder)
             event, context = yield self.event_creation_handler.create_new_client_event(
                 builder=builder
             )
 
             event, context = yield self.add_display_name_to_third_party_invite(
-                room_version, event_dict, event, context
+                event_dict, event, context
             )
 
             try:
@@ -2315,18 +2304,14 @@ class FederationHandler(BaseHandler):
         Returns:
             Deferred: resolves (to None)
         """
-        room_version = yield self.store.get_room_version(room_id)
-
-        # NB: event_dict has a particular specced format we might need to fudge
-        # if we change event formats too much.
-        builder = self.event_builder_factory.new(room_version, event_dict)
+        builder = self.event_builder_factory.new(event_dict)
 
         event, context = yield self.event_creation_handler.create_new_client_event(
             builder=builder,
         )
 
         event, context = yield self.add_display_name_to_third_party_invite(
-            room_version, event_dict, event, context
+            event_dict, event, context
         )
 
         try:
@@ -2346,8 +2331,7 @@ class FederationHandler(BaseHandler):
         yield member_handler.send_membership_event(None, event, context)
 
     @defer.inlineCallbacks
-    def add_display_name_to_third_party_invite(self, room_version, event_dict,
-                                               event, context):
+    def add_display_name_to_third_party_invite(self, event_dict, event, context):
         key = (
             EventTypes.ThirdPartyInvite,
             event.content["third_party_invite"]["signed"]["token"]
@@ -2371,7 +2355,7 @@ class FederationHandler(BaseHandler):
             # auth checks. If we need the invite and don't have it then the
             # auth check code will explode appropriately.
 
-        builder = self.event_builder_factory.new(room_version, event_dict)
+        builder = self.event_builder_factory.new(event_dict)
         EventValidator().validate_new(builder)
         event, context = yield self.event_creation_handler.create_new_client_event(
             builder=builder,
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 7aaa4fba33..a7cd779b02 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -278,15 +278,7 @@ class EventCreationHandler(object):
         """
         yield self.auth.check_auth_blocking(requester.user.to_string())
 
-        if event_dict["type"] == EventTypes.Create and event_dict["state_key"] == "":
-            room_version = event_dict["content"]["room_version"]
-        else:
-            try:
-                room_version = yield self.store.get_room_version(event_dict["room_id"])
-            except NotFoundError:
-                raise AuthError(403, "Unknown room")
-
-        builder = self.event_builder_factory.new(room_version, event_dict)
+        builder = self.event_builder_factory.new(event_dict)
 
         self.validator.validate_new(builder)
 
diff --git a/synapse/replication/http/federation.py b/synapse/replication/http/federation.py
index 2e16c69666..64a79da162 100644
--- a/synapse/replication/http/federation.py
+++ b/synapse/replication/http/federation.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.events import event_type_from_format_version
+from synapse.events import FrozenEvent
 from synapse.events.snapshot import EventContext
 from synapse.http.servlet import parse_json_object_from_request
 from synapse.replication.http._base import ReplicationEndpoint
@@ -70,7 +70,6 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
 
             event_payloads.append({
                 "event": event.get_pdu_json(),
-                "event_format_version": event.format_version,
                 "internal_metadata": event.internal_metadata.get_dict(),
                 "rejected_reason": event.rejected_reason,
                 "context": serialized_context,
@@ -95,12 +94,9 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
             event_and_contexts = []
             for event_payload in event_payloads:
                 event_dict = event_payload["event"]
-                format_ver = content["event_format_version"]
                 internal_metadata = event_payload["internal_metadata"]
                 rejected_reason = event_payload["rejected_reason"]
-
-                EventType = event_type_from_format_version(format_ver)
-                event = EventType(event_dict, internal_metadata, rejected_reason)
+                event = FrozenEvent(event_dict, internal_metadata, rejected_reason)
 
                 context = yield EventContext.deserialize(
                     self.store, event_payload["context"],
diff --git a/synapse/replication/http/send_event.py b/synapse/replication/http/send_event.py
index 3635015eda..5b52c91650 100644
--- a/synapse/replication/http/send_event.py
+++ b/synapse/replication/http/send_event.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.events import event_type_from_format_version
+from synapse.events import FrozenEvent
 from synapse.events.snapshot import EventContext
 from synapse.http.servlet import parse_json_object_from_request
 from synapse.replication.http._base import ReplicationEndpoint
@@ -74,7 +74,6 @@ class ReplicationSendEventRestServlet(ReplicationEndpoint):
 
         payload = {
             "event": event.get_pdu_json(),
-            "event_format_version": event.format_version,
             "internal_metadata": event.internal_metadata.get_dict(),
             "rejected_reason": event.rejected_reason,
             "context": serialized_context,
@@ -91,12 +90,9 @@ class ReplicationSendEventRestServlet(ReplicationEndpoint):
             content = parse_json_object_from_request(request)
 
             event_dict = content["event"]
-            format_ver = content["event_format_version"]
             internal_metadata = content["internal_metadata"]
             rejected_reason = content["rejected_reason"]
-
-            EventType = event_type_from_format_version(format_ver)
-            event = EventType(event_dict, internal_metadata, rejected_reason)
+            event = FrozenEvent(event_dict, internal_metadata, rejected_reason)
 
             requester = Requester.deserialize(self.store, content["requester"])
             context = yield EventContext.deserialize(self.store, content["context"])
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py
index 0a0ca58fc4..599f892858 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -23,7 +23,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventFormatVersions
 from synapse.api.errors import NotFoundError
-from synapse.events import FrozenEvent, event_type_from_format_version  # noqa: F401
+from synapse.events import FrozenEvent
 # these are only included to make the type annotations work
 from synapse.events.snapshot import EventContext  # noqa: F401
 from synapse.events.utils import prune_event
@@ -412,7 +412,11 @@ class EventsWorkerStore(SQLBaseStore):
                 # of a event format version, so it must be a V1 event.
                 format_version = EventFormatVersions.V1
 
-            original_ev = event_type_from_format_version(format_version)(
+            # TODO: When we implement new event formats we'll need to use a
+            # different event python type
+            assert format_version == EventFormatVersions.V1
+
+            original_ev = FrozenEvent(
                 event_dict=d,
                 internal_metadata_dict=internal_metadata,
                 rejected_reason=rejected_reason,
diff --git a/tests/storage/test_redaction.py b/tests/storage/test_redaction.py
index 3957561b1e..02bf975fbf 100644
--- a/tests/storage/test_redaction.py
+++ b/tests/storage/test_redaction.py
@@ -18,7 +18,7 @@ from mock import Mock
 
 from twisted.internet import defer
 
-from synapse.api.constants import EventTypes, Membership, RoomVersions
+from synapse.api.constants import EventTypes, Membership
 from synapse.types import RoomID, UserID
 
 from tests import unittest
@@ -52,7 +52,6 @@ class RedactionTestCase(unittest.TestCase):
         content = {"membership": membership}
         content.update(extra_content)
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": EventTypes.Member,
                 "sender": user.to_string(),
@@ -75,7 +74,6 @@ class RedactionTestCase(unittest.TestCase):
         self.depth += 1
 
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": EventTypes.Message,
                 "sender": user.to_string(),
@@ -96,7 +94,6 @@ class RedactionTestCase(unittest.TestCase):
     @defer.inlineCallbacks
     def inject_redaction(self, room, event_id, user, reason):
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": EventTypes.Redaction,
                 "sender": user.to_string(),
diff --git a/tests/storage/test_roommember.py b/tests/storage/test_roommember.py
index 7fa2f4fd70..978c66133d 100644
--- a/tests/storage/test_roommember.py
+++ b/tests/storage/test_roommember.py
@@ -18,7 +18,7 @@ from mock import Mock
 
 from twisted.internet import defer
 
-from synapse.api.constants import EventTypes, Membership, RoomVersions
+from synapse.api.constants import EventTypes, Membership
 from synapse.types import RoomID, UserID
 
 from tests import unittest
@@ -50,7 +50,6 @@ class RoomMemberStoreTestCase(unittest.TestCase):
     @defer.inlineCallbacks
     def inject_room_member(self, room, user, membership, replaces_state=None):
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": EventTypes.Member,
                 "sender": user.to_string(),
diff --git a/tests/storage/test_state.py b/tests/storage/test_state.py
index a1f99134dc..086a39d834 100644
--- a/tests/storage/test_state.py
+++ b/tests/storage/test_state.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.api.constants import EventTypes, Membership, RoomVersions
+from synapse.api.constants import EventTypes, Membership
 from synapse.storage.state import StateFilter
 from synapse.types import RoomID, UserID
 
@@ -52,7 +52,6 @@ class StateStoreTestCase(tests.unittest.TestCase):
     @defer.inlineCallbacks
     def inject_state_event(self, room, sender, typ, state_key, content):
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": typ,
                 "sender": sender.to_string(),
diff --git a/tests/test_visibility.py b/tests/test_visibility.py
index 82d63ce00e..2eea3b098b 100644
--- a/tests/test_visibility.py
+++ b/tests/test_visibility.py
@@ -17,7 +17,6 @@ import logging
 from twisted.internet import defer
 from twisted.internet.defer import succeed
 
-from synapse.api.constants import RoomVersions
 from synapse.events import FrozenEvent
 from synapse.visibility import filter_events_for_server
 
@@ -125,7 +124,6 @@ class FilterEventsForServerTestCase(tests.unittest.TestCase):
     def inject_visibility(self, user_id, visibility):
         content = {"history_visibility": visibility}
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": "m.room.history_visibility",
                 "sender": user_id,
@@ -146,7 +144,6 @@ class FilterEventsForServerTestCase(tests.unittest.TestCase):
         content = {"membership": membership}
         content.update(extra_content)
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": "m.room.member",
                 "sender": user_id,
@@ -168,7 +165,6 @@ class FilterEventsForServerTestCase(tests.unittest.TestCase):
         if content is None:
             content = {"body": "testytest"}
         builder = self.event_builder_factory.new(
-            RoomVersions.V1,
             {
                 "type": "m.room.message",
                 "sender": user_id,
diff --git a/tests/utils.py b/tests/utils.py
index 2dfcb70a93..df73c539c3 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -26,7 +26,7 @@ from six.moves.urllib import parse as urlparse
 
 from twisted.internet import defer, reactor
 
-from synapse.api.constants import EventTypes, RoomVersions
+from synapse.api.constants import EventTypes
 from synapse.api.errors import CodeMessageException, cs_error
 from synapse.config.server import ServerConfig
 from synapse.federation.transport import server
@@ -624,7 +624,6 @@ def create_room(hs, room_id, creator_id):
     event_creation_handler = hs.get_event_creation_handler()
 
     builder = event_builder_factory.new(
-        RoomVersions.V1,
         {
             "type": EventTypes.Create,
             "state_key": "",