Improve documentation for backfilling rooms

There's not a whole lot to improve here - most of the changes are about reorganization and minor clarifications.

api/server-server/backfill.yaml

@@ -0,0 +1,77 @@
+# Copyright 2018 New Vector Ltd
+#
+# 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.
+
+swagger: '2.0'
+info:
+  title: "Matrix Federation Events API"
+  version: "1.0.0"
+host: localhost:8448
+schemes:
+  - https
+basePath: /_matrix/federation/v1
+produces:
+  - application/json
+paths:
+  "/backfill/{roomId}":
+    get:
+      summary: Retrieves the events which precede the given event
+      description: |-
+        Retreives a sliding-window history of previous PDUs that occurred in the given room.
+        Starting from the PDU ID(s) given in the ``v`` argument, the PDUs that preceded it
+        are retrieved, up to the total number given by the ``limit``.
+      operationId: backfillRoom
+      parameters:
+        - in: path
+          name: roomId
+          type: string
+          description: The room ID to backfill.
+          required: true
+          x-example: "!SomeRoom:matrix.org"
+        - in: query
+          name: v
+          type: array
+          items:
+            type: string
+          description: The event IDs to backfill from. 
+          required: true
+          x-example: ["$abc123:matrix.org"]
+        - in: query
+          name: limit
+          type: integer
+          description: The maximum number of PDUs to retrieve, including the given events.
+          required: true
+          x-example: 2
+      responses:
+        200:
+          description: |-
+            A transaction containing the PDUs that preceded the given event(s), including the given
+            event(s), up to the given limit.
+          schema:
+            $ref: "definitions/transaction.yaml"
+          # Override the example to show the response of the request a bit better
+          examples:
+            application/json: {
+              "$ref": "examples/transaction.json",
+              "pdus": [
+                {
+                  "$ref": "pdu.json",
+                  "room_id": "!SomeRoom:matrix.org",
+                  "event_id": "$abc123:matrix.org"
+                },
+                {
+                  "$ref": "pdu.json",
+                  "room_id": "!SomeRoom:matrix.org"
+                },
+              ]
+            }

api/server-server/events.yaml

@@ -59,35 +59,3 @@ paths:
           description: A transaction containing a single PDU which is the event requested.
           schema:
             $ref: "definitions/transaction.yaml"
-  "/backfill/{roomId}":
-    get:
-      summary: Retrieves the events which precede the given event
-      description: |-
-        Retreives a sliding-window history of previous PDUs that occurred in the given room.
-        Starting from the PDU ID(s) given in the ``v`` argument, the PDUs that preceded it
-        are retrieved, up to the total number given by the ``limit``.
-      operationId: backfillRoom
-      parameters:
-        - in: path
-          name: roomId
-          type: string
-          description: The room ID to backfill.
-          required: true
-          x-example: "!abc123:matrix.org"
-        - in: query
-          name: v
-          type: string # TODO: The description says this is plural - figure out how to specify multiple, and spec it
-          description: The event ID to backfill from.
-          required: true
-          x-example: "$abc123:matrix.org"
-        - in: query
-          name: limit
-          type: integer
-          description: The maximum number of events to retrieve.
-          required: true
-          x-example: 10
-      responses:
-        200:
-          description: A transaction containing the PDUs that preceded the given event(s).
-          schema:
-            $ref: "definitions/transaction.yaml"

specification/server_server_api.rst

@@ -850,32 +850,17 @@ To cover this case, the federation API provides a server-to-server analog of
 the ``/messages`` client API, allowing one homeserver to fetch history from
 another. This is the ``/backfill`` API.
 
-To request more history, the requesting homeserver picks another homeserver
-that it thinks may have more (most likely this should be a homeserver for some
-of the existing users in the room at the earliest point in history it has
-currently), and makes a ``/backfill`` request. The parameters of this request
-give an event ID that the requesting homeserver wishes to obtain, and a number
-specifying how many more events of history before that one to return at most.
-
-The response to this request is an object with the following keys:
-
-======================== ============ =========================================
- Key                      Type         Description
-======================== ============ =========================================
-``pdus``                 List         A list of events.
-``origin``               String       The name of the resident homeserver.
-``origin_server_ts``     Integer      A timestamp added by the resident
-                                      homeserver.
-======================== ============ =========================================
-
-The list of events given in ``pdus`` is returned in reverse chronological
-order; having the most recent event first (i.e. the event whose event ID is
-that requested by the requester in the ``v`` parameter).
+To request more history, the requesting homeserver picks another homeserver 
+that it thinks may have more (most likely this should be a homeserver for 
+some of the existing users in the room at the earliest point in history it 
+has currently), and makes a ``/backfill`` request.
 
 .. TODO-spec
   Specify (or remark that it is unspecified) how the server handles divergent
   history. DFS? BFS? Anything weirder?
 
+{{backfill_ss_http_api}}
+
 Inviting to a room
 ------------------