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diff --git a/synapse/api/events/__init__.py b/synapse/api/events/__init__.py
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+++ b/synapse/api/events/__init__.py
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+# -*- coding: utf-8 -*-
+# Copyright 2014 matrix.org
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from synapse.api.errors import SynapseError, Codes
+from synapse.util.jsonobject import JsonEncodedObject
+
+
+class SynapseEvent(JsonEncodedObject):
+
+    """Base class for Synapse events. These are JSON objects which must abide
+    by a certain well-defined structure.
+    """
+
+    # Attributes that are currently assumed by the federation side:
+    # Mandatory:
+    # - event_id
+    # - room_id
+    # - type
+    # - is_state
+    #
+    # Optional:
+    # - state_key (mandatory when is_state is True)
+    # - prev_events (these can be filled out by the federation layer itself.)
+    # - prev_state
+
+    valid_keys = [
+        "event_id",
+        "type",
+        "room_id",
+        "user_id",  # sender/initiator
+        "content",  # HTTP body, JSON
+    ]
+
+    internal_keys = [
+        "is_state",
+        "state_key",
+        "prev_events",
+        "prev_state",
+        "depth",
+        "destinations",
+        "origin",
+    ]
+
+    required_keys = [
+        "event_id",
+        "room_id",
+        "content",
+    ]
+
+    def __init__(self, raises=True, **kwargs):
+        super(SynapseEvent, self).__init__(**kwargs)
+        if "content" in kwargs:
+            self.check_json(self.content, raises=raises)
+
+    def get_content_template(self):
+        """ Retrieve the JSON template for this event as a dict.
+
+        The template must be a dict representing the JSON to match. Only
+        required keys should be present. The values of the keys in the template
+        are checked via type() to the values of the same keys in the actual
+        event JSON.
+
+        NB: If loading content via json.loads, you MUST define strings as
+        unicode.
+
+        For example:
+            Content:
+                {
+                    "name": u"bob",
+                    "age": 18,
+                    "friends": [u"mike", u"jill"]
+                }
+            Template:
+                {
+                    "name": u"string",
+                    "age": 0,
+                    "friends": [u"string"]
+                }
+            The values "string" and 0 could be anything, so long as the types
+            are the same as the content.
+        """
+        raise NotImplementedError("get_content_template not implemented.")
+
+    def check_json(self, content, raises=True):
+        """Checks the given JSON content abides by the rules of the template.
+
+        Args:
+            content : A JSON object to check.
+            raises: True to raise a SynapseError if the check fails.
+        Returns:
+            True if the content passes the template. Returns False if the check
+            fails and raises=False.
+        Raises:
+            SynapseError if the check fails and raises=True.
+        """
+        # recursively call to inspect each layer
+        err_msg = self._check_json(content, self.get_content_template())
+        if err_msg:
+            if raises:
+                raise SynapseError(400, err_msg, Codes.BAD_JSON)
+            else:
+                return False
+        else:
+            return True
+
+    def _check_json(self, content, template):
+        """Check content and template matches.
+
+        If the template is a dict, each key in the dict will be validated with
+        the content, else it will just compare the types of content and
+        template. This basic type check is required because this function will
+        be recursively called and could be called with just strs or ints.
+
+        Args:
+            content: The content to validate.
+            template: The validation template.
+        Returns:
+            str: An error message if the validation fails, else None.
+        """
+        if type(content) != type(template):
+            return "Mismatched types: %s" % template
+
+        if type(template) == dict:
+            for key in template:
+                if key not in content:
+                    return "Missing %s key" % key
+
+                if type(content[key]) != type(template[key]):
+                    return "Key %s is of the wrong type." % key
+
+                if type(content[key]) == dict:
+                    # we must go deeper
+                    msg = self._check_json(content[key], template[key])
+                    if msg:
+                        return msg
+                elif type(content[key]) == list:
+                    # make sure each item type in content matches the template
+                    for entry in content[key]:
+                        msg = self._check_json(entry, template[key][0])
+                        if msg:
+                            return msg