The diagram is incomplete. The following things aren't shown on the diagram:
Diagram:
W -> Writer
S -> Server/Store/Service/Something/Stuff
R -> Reader
+---+ +---+ +---+
+----------| W | +----------| S | +--------| R |
| +---+ | Receipts +---+ | Client +---+
| Federation |>=========================================>| Server |>=====================>| Sync |
| Receiver | | | | |
| | +---+ | | | |
| | +--------| W | | | | |
| | | Client +---+ | | | |
| | | Receipt |>=====>| | | |
| | | Updater | | | | |
| | +----------+ | | | |
| | | | | |
| | +---+ +---+ | | +---+ | |
| | +------------| W | +------| S | | | +--------| R | | |
| | | Federation +---+ | Room +---+ | | | Client +---+ | |
| | | Backfill |>=====>| Server |>=====>| |>=====>| Push | | |
| | +--------------+ | | +------------+ | | | |
| | | | | | | |
| | | |>==========================>| | | |
| | | | +----------+ | |
| | | | | |
| | | | +---+ | |
| | | | +--------| R | | |
| | | | | Client +---+ | |
| |>========================>| |>==========================>| Search | | |
| | | | | | | |
| | | | +----------+ | |
| | | | | |
| | | |>==========================================>| |
| | | | | |
| | +---+ | | +---+ | |
| | +--------| W | | | +----------| S | | |
| | | Client +---+ | | | Presence +---+ | |
| | | API |>=====>| |>=====>| Server |>=====================>| |
| | | /send | +--------+ | | | |
| | | | | | | |
| | | |>======================>| |<=====================<| |
| | +----------+ | | | |
| | | | | |
| | +---+ | | | |
| | +--------| W | | | | |
| | | Client +---+ | | | |
| | | Presence |>=====>| | | |
| | | Setter | | | | |
| | +----------+ | | | |
| | | | | |
| | | | | |
| |>=========================================>| | | |
| | +------------+ | |
| | | |
| | +---+ | |
| | +----------| S | | |
| | | Typing +---+ | |
| |>=========================================>| Server |>=====================>| |
+------------+ | | +----------+
+---+ | |
+--------| W | | |
| Client +---+ | |
| Typing |>=====>| |
| Setter | | |
+----------+ +------------+
Many of the components are logical rather than physical. For example it is possible that all of the client API writers will end up being glued together and always deployed as a single unit.
Outbound federation requests will probably need to be funnelled through a choke-point to implement ratelimiting and backoff correctly.
/federation/v1/send/
requests.prev_events
from the remote server if needed./client/v1/rooms/
that create room events.