103 lines
4.1 KiB
Markdown
103 lines
4.1 KiB
Markdown
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# Dendrite
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Dendrite will be a matrix homeserver written in go.
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# Design
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*
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## Log Based Architecture
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### Decomposition and Decoupling
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A matrix homeserver can be built around append-only event logs built from the
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messages, receipts, presence, typing notifications, device messages and other
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events sent by users on the homeservers or by other homeservers.
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The server would then decompose into two categories: writers that add new
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entries to the logs and readers that read those entries.
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The event logs then serve to decouple the two components, the writers and
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readers need only agree on the format of the entries in the event log.
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This format could be largely dervived from the wire format of the events used
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in the client and federation protocols:
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C-S API +---------+ Event Log +---------+ C-S API
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---------> | |+ (e.g. kafka) | |+ --------->
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| Writers || =============> | Readers ||
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---------> | || | || --------->
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S-S API +---------+| +---------+| S-S API
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+---------+ +---------+
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However the way matrix handles state events in a room creates a few
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complications for this model.
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1) Writers require the room state at an event to check if it is allowed.
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2) Readers require the room state at an event to determine the users and
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servers that are allowed to see the event.
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3) A client can query the current state of the room from a reader.
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The writers and readers cannot extract the necessary information directly from
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the event logs because it would take to long to extract the information as the
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state is built up by collecting individual state events from the event history.
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The writers and readers therefore need access to something that stores copies
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of the event state in a form that can be efficiently queried. One possibility
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would be for the readers and writers to maintain copies of the current state
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in local databases. A second possibility would be to add a dedicated component
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that maintained the state of the room and exposed an API that the readers and
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writers could query to get the state. The second has the advantage that the
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state is calculated and stored in a single location.
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C-S API +---------+ Log +--------+ Log +---------+ C-S API
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---------> | |+ ======> | | ======> | |+ --------->
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| Writers || | Room | | Readers ||
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---------> | || <------ | Server | ------> | || --------->
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S-S API +---------+| Query | | Query +---------+| S-S API
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+---------+ +--------+ +---------+
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The room server can annotate the events it logs to the readers with room state
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so that the readers can avoid querying the room server unnecessarily.
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[This architecture can be extended to cover most of the APIs.](WIRING.md)
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# TODO
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- [ ] gomatrixlib
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- [x] Canonical JSON.
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- [x] Signed JSON.
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- [ ] Event hashing.
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- [ ] Event signing.
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- [x] Federation server discovery.
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- [x] Federation key lookup.
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- [ ] Federation request signing.
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- [x] Event authentication.
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- [ ] Event visibility.
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- [ ] State resolution.
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- [ ] Third party invites authentication.
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- [ ] Room Server
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- [ ] Inputing new events from logs.
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- [ ] Inputing backfilled events from logs.
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- [ ] Outputing events and current state to logs.
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- [ ] Querying state at an event.
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- [ ] Querying current forward extremities and state.
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- [ ] Querying message history.
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- [ ] Exporting/importing messages from other servers.
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- [ ] Other Room Server stuff.
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- [ ] Client Room Send
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- [ ] Handling /client/r0/room/... HTTP PUTs
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- [ ] Talk to remote servers for joins to remote servers.
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- [ ] Outputting new events to logs.
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- [ ] Updating the last active time in presence.
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- [ ] Other Client Room Send stuff.
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- [ ] Client Sync
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- [ ] Inputing new room events and state from the logs.
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- [ ] Handling /client/r0/sync HTTP GETs
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- [ ] Outputing whether the client is syncing to the logs.
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- [ ] Other Client Sync Stuff.
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- [ ] Other Components.
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