You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
523 lines
22 KiB
ReStructuredText
523 lines
22 KiB
ReStructuredText
Matrix Specification
|
|
====================
|
|
|
|
Version: {{spec_version}}
|
|
-----------------------------
|
|
This specification has been generated from
|
|
https://github.com/matrix-org/matrix-doc using
|
|
https://github.com/matrix-org/matrix-doc/blob/master/scripts/gendoc.py as of
|
|
revision ``{{git_version}}`` - https://github.com/matrix-org/matrix-doc/tree/{{git_rev}}
|
|
|
|
Changelog
|
|
~~~~~~~~~
|
|
{{spec_changelog}}
|
|
|
|
For a full changelog, see
|
|
https://github.com/matrix-org/matrix-doc/blob/master/CHANGELOG.rst
|
|
|
|
.. contents:: Table of Contents
|
|
.. sectnum::
|
|
|
|
Introduction
|
|
============
|
|
.. WARNING::
|
|
The Matrix specification is still evolving: the APIs are not yet frozen
|
|
and this document is in places a work in progress or stale. We have made every
|
|
effort to clearly flag areas which are still being finalised.
|
|
|
|
We're publishing it at this point because it's complete enough to be more than
|
|
useful and provide a canonical reference to how Matrix is evolving. Our end
|
|
goal is to mirror WHATWG's `Living Standard
|
|
<http://wiki.whatwg.org/wiki/FAQ#What_does_.22Living_Standard.22_mean.3F>`_.
|
|
|
|
Matrix is a set of open APIs for open-federated Instant Messaging (IM), Voice
|
|
over IP (VoIP) and Internet of Things (IoT) communication, designed to create
|
|
and support a new global real-time communication ecosystem. The intention is to
|
|
provide an open decentralised pubsub layer for the internet for securely
|
|
persisting and publishing/subscribing JSON objects.
|
|
|
|
This specification is the ongoing result of standardising the APIs used by the
|
|
various components of the Matrix ecosystem to communicate with one another.
|
|
|
|
The principles that Matrix attempts to follow are:
|
|
|
|
- Pragmatic Web-friendly APIs (i.e. JSON over REST)
|
|
- Keep It Simple & Stupid
|
|
|
|
+ provide a simple architecture with minimal third-party dependencies.
|
|
|
|
- Fully open:
|
|
|
|
+ Fully open federation - anyone should be able to participate in the global
|
|
Matrix network
|
|
+ Fully open standard - publicly documented standard with no IP or patent
|
|
licensing encumbrances
|
|
+ Fully open source reference implementation - liberally-licensed example
|
|
implementations with no IP or patent licensing encumbrances
|
|
|
|
- Empowering the end-user
|
|
|
|
+ The user should be able to choose the server and clients they use
|
|
+ The user should be control how private their communication is
|
|
+ The user should know precisely where their data is stored
|
|
|
|
- Fully decentralised - no single points of control over conversations or the
|
|
network as a whole
|
|
- Learning from history to avoid repeating it
|
|
|
|
+ Trying to take the best aspects of XMPP, SIP, IRC, SMTP, IMAP and NNTP
|
|
whilst trying to avoid their failings
|
|
|
|
The functionality that Matrix provides includes:
|
|
|
|
- Creation and management of fully distributed chat rooms with no
|
|
single points of control or failure
|
|
- Eventually-consistent cryptographically secure synchronisation of room
|
|
state across a global open network of federated servers and services
|
|
- Sending and receiving extensible messages in a room with (optional)
|
|
end-to-end encryption
|
|
- Extensible user management (inviting, joining, leaving, kicking, banning)
|
|
mediated by a power-level based user privilege system.
|
|
- Extensible room state management (room naming, aliasing, topics, bans)
|
|
- Extensible user profile management (avatars, displaynames, etc)
|
|
- Managing user accounts (registration, login, logout)
|
|
- Use of 3rd Party IDs (3PIDs) such as email addresses, phone numbers,
|
|
Facebook accounts to authenticate, identify and discover users on Matrix.
|
|
- Trusted federation of Identity servers for:
|
|
|
|
+ Publishing user public keys for PKI
|
|
+ Mapping of 3PIDs to Matrix IDs
|
|
|
|
The end goal of Matrix is to be a ubiquitous messaging layer for synchronising
|
|
arbitrary data between sets of people, devices and services - be that for
|
|
instant messages, VoIP call setups, or any other objects that need to be
|
|
reliably and persistently pushed from A to B in an interoperable and federated
|
|
manner.
|
|
|
|
Overview
|
|
========
|
|
|
|
Architecture
|
|
------------
|
|
|
|
Matrix defines APIs for synchronising extensible JSON objects known as
|
|
``events`` between compatible clients, servers and services. Clients are
|
|
typically messaging/VoIP applications or IoT devices/hubs and communicate by
|
|
synchronising communication history with their ``homeserver`` using the
|
|
``Client-Server API``. Each homeserver stores the communication history and
|
|
account information for all of its clients, and shares data with the wider
|
|
Matrix ecosystem by synchronising communication history with other homeservers
|
|
and their clients.
|
|
|
|
Clients typically communicate with each other by emitting events in the
|
|
context of a virtual ``room``. Room data is replicated across *all of the
|
|
homeservers* whose users are participating in a given room. As such, *no
|
|
single homeserver has control or ownership over a given room*. Homeservers
|
|
model communication history as a partially ordered graph of events known as
|
|
the room's ``event graph``, which is synchronised with eventual consistency
|
|
between the participating servers using the ``Server-Server API``. This process
|
|
of synchronising shared conversation history between homeservers run by
|
|
different parties is called ``Federation``. Matrix optimises for the the
|
|
Availability and Partitioned properties of CAP theorem at
|
|
the expense of Consistency.
|
|
|
|
For example, for client A to send a message to client B, client A performs an
|
|
HTTP PUT of the required JSON event on its homeserver (HS) using the
|
|
client-server API. A's HS appends this event to its copy of the room's event
|
|
graph, signing the message in the context of the graph for integrity. A's HS
|
|
then replicates the message to B's HS by performing an HTTP PUT using the
|
|
server-server API. B's HS authenticates the request, validates the event's
|
|
signature, authorises the event's contents and then adds it to its copy of the
|
|
room's event graph. Client B then receives the message from his homeserver via
|
|
a long-lived GET request.
|
|
|
|
::
|
|
|
|
How data flows between clients
|
|
==============================
|
|
|
|
{ Matrix client A } { Matrix client B }
|
|
^ | ^ |
|
|
| events | Client-Server API | events |
|
|
| V | V
|
|
+------------------+ +------------------+
|
|
| |---------( HTTPS )--------->| |
|
|
| Home Server | | Home Server |
|
|
| |<--------( HTTPS )----------| |
|
|
+------------------+ Server-Server API +------------------+
|
|
History Synchronisation
|
|
(Federation)
|
|
|
|
|
|
Users
|
|
~~~~~
|
|
|
|
Each client is associated with a user account, which is identified in Matrix
|
|
using a unique "User ID". This ID is namespaced to the home server which
|
|
allocated the account and has the form::
|
|
|
|
@localpart:domain
|
|
|
|
The ``localpart`` of a user ID may be a user name, or an opaque ID identifying
|
|
this user. They are case-insensitive.
|
|
|
|
.. TODO-spec
|
|
- Need to specify precise grammar for Matrix IDs
|
|
|
|
Events
|
|
~~~~~~
|
|
|
|
All data exchanged over Matrix is expressed as an "event". Typically each client
|
|
action (e.g. sending a message) correlates with exactly one event. Each event
|
|
has a ``type`` which is used to differentiate different kinds of data. ``type``
|
|
values MUST be uniquely globally namespaced following Java's `package naming
|
|
conventions
|
|
<http://docs.oracle.com/javase/specs/jls/se5.0/html/packages.html#7.7>`, e.g.
|
|
``com.example.myapp.event``. The special top-level namespace ``m.`` is reserved
|
|
for events defined in the Matrix specification - for instance ``m.room.message``
|
|
is the event type for instant messages. Events are usually sent in the context
|
|
of a "Room".
|
|
|
|
Event Graphs
|
|
~~~~~~~~~~~~
|
|
|
|
Events exchanged in the context of a room are stored in a directed acyclic graph
|
|
(DAG) called an ``event graph``. The partial ordering of this graph gives the
|
|
chronological ordering of events within the room. Each event in the graph has a
|
|
list of zero or more ``parent`` events, which refer to any preceeding events
|
|
which have no chronological successor from the perspective of the homeserver
|
|
which created the event.
|
|
|
|
Typically an event has a single parent: the most recent message in the room at
|
|
the point it was sent. However, homeservers may legitimately race with each
|
|
other when sending messages, resulting in a single event having multiple
|
|
successors. The next event added to the graph thus will have multiple parents.
|
|
Every event graph has a single root event with no parent.
|
|
|
|
To order and ease chronological comparison between the events within the graph,
|
|
homeservers maintain a ``depth`` metadata field on each event. An event's
|
|
``depth`` is a positive integer that is strictly greater than the depths of any
|
|
of its parents. The root event should have a depth of 1. Thus if one event is
|
|
before another, then it must have a strictly smaller depth.
|
|
|
|
Room structure
|
|
~~~~~~~~~~~~~~
|
|
|
|
A room is a conceptual place where users can send and receive events. Events are
|
|
sent to a room, and all participants in that room with sufficient access will
|
|
receive the event. Rooms are uniquely identified internally via "Room IDs",
|
|
which have the form::
|
|
|
|
!opaque_id:domain
|
|
|
|
There is exactly one room ID for each room. Whilst the room ID does contain a
|
|
domain, it is simply for globally namespacing room IDs. The room does NOT
|
|
reside on the domain specified. Room IDs are not meant to be human readable.
|
|
They are case-sensitive.
|
|
|
|
The following conceptual diagram shows an ``m.room.message`` event being sent to
|
|
the room ``!qporfwt:matrix.org``::
|
|
|
|
{ @alice:matrix.org } { @bob:domain.com }
|
|
| ^
|
|
| |
|
|
[HTTP POST] [HTTP GET]
|
|
Room ID: !qporfwt:matrix.org Room ID: !qporfwt:matrix.org
|
|
Event type: m.room.message Event type: m.room.message
|
|
Content: { JSON object } Content: { JSON object }
|
|
| |
|
|
V |
|
|
+------------------+ +------------------+
|
|
| Home Server | | Home Server |
|
|
| matrix.org | | domain.com |
|
|
+------------------+ +------------------+
|
|
| ^
|
|
| [HTTP PUT] |
|
|
| Room ID: !qporfwt:matrix.org |
|
|
| Event type: m.room.message |
|
|
| Content: { JSON object } |
|
|
`-------> Pointer to the preceding message ------`
|
|
PKI signature from matrix.org
|
|
Transaction-layer metadata
|
|
PKI Authorization header
|
|
|
|
...................................
|
|
| Shared Data |
|
|
| State: |
|
|
| Room ID: !qporfwt:matrix.org |
|
|
| Servers: matrix.org, domain.com |
|
|
| Members: |
|
|
| - @alice:matrix.org |
|
|
| - @bob:domain.com |
|
|
| Messages: |
|
|
| - @alice:matrix.org |
|
|
| Content: { JSON object } |
|
|
|...................................|
|
|
|
|
Federation maintains *shared data structures* per-room between multiple home
|
|
servers. The data is split into ``message events`` and ``state events``.
|
|
|
|
``Message events`` describe transient 'once-off' activity in a room such as an
|
|
instant messages, VoIP call setups, file transfers, etc. They generally describe
|
|
communication activity.
|
|
|
|
``State events`` describe updates to a given piece of persistent information
|
|
('state') related to a room, such as the room's name, topic, membership,
|
|
participating servers, etc. State is modelled as a lookup table of key/value
|
|
pairs per room, with each key being a tuple of ``state_key`` and ``event type``.
|
|
Each state event updates the value of a given key.
|
|
|
|
The state of the room at a given point is calculated by considering all events
|
|
preceding and including a given event in the graph. Where events describe the
|
|
same state, a merge conflict algorithm is applied. The state resolution
|
|
algorithm is transitive and does not depend on server state, as it must
|
|
consistently select the same event irrespective of the server or the order the
|
|
events were received in.
|
|
|
|
Events are signed by the originating server (the signature includes the parent
|
|
relations, type, depth and payload hash) and are pushed over federation to the
|
|
participating servers in a room, currently using full mesh topology. Servers may
|
|
also request backfill of events over federation from the other servers
|
|
participating in a room.
|
|
|
|
|
|
Room Aliases
|
|
++++++++++++
|
|
|
|
Each room can also have multiple "Room Aliases", which look like::
|
|
|
|
#room_alias:domain
|
|
|
|
.. TODO
|
|
- Need to specify precise grammar for Room Aliases
|
|
|
|
A room alias "points" to a room ID and is the human-readable label by which
|
|
rooms are publicised and discovered. The room ID the alias is pointing to can
|
|
be obtained by visiting the domain specified. They are case-insensitive. Note
|
|
that the mapping from a room alias to a room ID is not fixed, and may change
|
|
over time to point to a different room ID. For this reason, Clients SHOULD
|
|
resolve the room alias to a room ID once and then use that ID on subsequent
|
|
requests.
|
|
|
|
When resolving a room alias the server will also respond with a list of servers
|
|
that are in the room that can be used to join via.
|
|
|
|
::
|
|
|
|
HTTP GET
|
|
#matrix:domain.com !aaabaa:matrix.org
|
|
| ^
|
|
| |
|
|
_______V____________________|____
|
|
| domain.com |
|
|
| Mappings: |
|
|
| #matrix >> !aaabaa:matrix.org |
|
|
| #golf >> !wfeiofh:sport.com |
|
|
| #bike >> !4rguxf:matrix.org |
|
|
|________________________________|
|
|
|
|
Identity
|
|
~~~~~~~~
|
|
|
|
Users in Matrix are identified via their matrix user ID (MXID). However,
|
|
existing 3rd party ID namespaces can also be used in order to identify Matrix
|
|
users. A Matrix "Identity" describes both the user ID and any other existing IDs
|
|
from third party namespaces *linked* to their account.
|
|
|
|
Matrix users can *link* third-party IDs (3PIDs) such as email addresses, social
|
|
network accounts and phone numbers to their user ID. Linking 3PIDs creates a
|
|
mapping from a 3PID to a user ID. This mapping can then be used by Matrix
|
|
users in order to discover the MXIDs of their contacts.
|
|
|
|
In order to ensure that the mapping from 3PID to user ID is genuine, a globally
|
|
federated cluster of trusted "Identity Servers" (IS) are used to verify the 3PID
|
|
and persist and replicate the mappings.
|
|
|
|
Usage of an IS is not required in order for a client application to be part of
|
|
the Matrix ecosystem. However, without one clients will not be able to look up
|
|
user IDs using 3PIDs.
|
|
|
|
Presence
|
|
~~~~~~~~
|
|
|
|
Each user has the concept of presence information. This encodes:
|
|
|
|
* Whether the user is currently online
|
|
* How recently the user was last active (as seen by the server)
|
|
* Whether a given client considers the user to be currently idle
|
|
* Arbitrary information about the user's current status (e.g. "in a meeting").
|
|
|
|
This information is collated from both per-device (online; idle; last_active) and
|
|
per-user (status) data, aggregated by the user's homeserver and transmitted as
|
|
an ``m.presence`` event. This is one of the few events which are sent *outside
|
|
the context of a room*. Presence events are sent to all users who subscribe to
|
|
this user's presence through a presence list or by sharing membership of a room.
|
|
|
|
.. TODO
|
|
How do we let users hide their presence information?
|
|
|
|
.. TODO
|
|
The last_active specifics should be moved to the detailed presence event section
|
|
|
|
Last activity is tracked by the server maintaining a timestamp of the last time
|
|
it saw a pro-active event from the user. Any event which could be triggered by a
|
|
human using the application is considered pro-active (e.g. sending an event to a
|
|
room). An example of a non-proactive client activity would be a client setting
|
|
'idle' presence status, or polling for events. This timestamp is presented via a
|
|
key called ``last_active_ago``, which gives the relative number of milliseconds
|
|
since the message is generated/emitted that the user was last seen active.
|
|
|
|
N.B. in v1 API, status/online/idle state are muxed into a single 'presence' field on the m.presence event.
|
|
|
|
Presence Lists
|
|
~~~~~~~~~~~~~~
|
|
|
|
Each user's home server stores a "presence list". This stores a list of user IDs
|
|
whose presence the user wants to follow.
|
|
|
|
To be added to this list, the user being added must be invited by the list owner
|
|
and accept the invitation. Once accepted, both user's HSes track the
|
|
subscription.
|
|
|
|
|
|
Profiles
|
|
~~~~~~~~
|
|
|
|
Users may publish arbitrary key/value data associated with their account - such
|
|
as a human readable ``display name``, a profile photo URL, contact information
|
|
(email address, phone nubers, website URLs etc).
|
|
|
|
In Client-Server API v2, profile data is typed using namespaced keys for
|
|
interoperability, much like events - e.g. ``m.profile.display_name``.
|
|
|
|
.. TODO
|
|
Actually specify the different types of data - e.g. what format are display
|
|
names allowed to be?
|
|
|
|
Private User Data
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
Users may also store arbitrary private key/value data in their account - such as
|
|
client preferences, or server configuration settings which lack any other
|
|
dedicated API. The API is symmetrical to managing Profile data.
|
|
|
|
.. TODO
|
|
Would it really be overengineered to use the same API for both profile &
|
|
private user data, but with different ACLs?
|
|
|
|
API Standards
|
|
-------------
|
|
|
|
The mandatory baseline for communication in Matrix is exchanging JSON objects
|
|
over HTTP APIs. HTTPS is mandated as the baseline for server-server
|
|
(federation) communication. HTTPS is recommended for client-server
|
|
communication, although HTTP may be supported as a fallback to support basic
|
|
HTTP clients. More efficient optional transports for client-server
|
|
communication will in future be supported as optional extensions - e.g. a
|
|
packed binary encoding over stream-cipher encrypted TCP socket for
|
|
low-bandwidth/low-roundtrip mobile usage.
|
|
|
|
.. TODO
|
|
We need to specify capability negotiation for extensible transports
|
|
|
|
For the default HTTP transport, all API calls use a Content-Type of
|
|
``application/json``. In addition, all strings MUST be encoded as UTF-8.
|
|
|
|
Clients are authenticated using opaque ``access_token`` strings (see
|
|
`Client Authentication`_ for details), passed as a query string parameter on
|
|
all requests.
|
|
|
|
.. TODO
|
|
Need to specify any HMAC or access_token lifetime/ratcheting tricks
|
|
|
|
Any errors which occur at the Matrix API level MUST return a "standard error
|
|
response". This is a JSON object which looks like::
|
|
|
|
{
|
|
"errcode": "<error code>",
|
|
"error": "<error message>"
|
|
}
|
|
|
|
The ``error`` string will be a human-readable error message, usually a sentence
|
|
explaining what went wrong. The ``errcode`` string will be a unique string
|
|
which can be used to handle an error message e.g. ``M_FORBIDDEN``. These error
|
|
codes should have their namespace first in ALL CAPS, followed by a single _ to
|
|
ease seperating the namespace from the error code.. For example, if there was a
|
|
custom namespace ``com.mydomain.here``, and a
|
|
``FORBIDDEN`` code, the error code should look like
|
|
``COM.MYDOMAIN.HERE_FORBIDDEN``. There may be additional keys depending on the
|
|
error, but the keys ``error`` and ``errcode`` MUST always be present.
|
|
|
|
Some standard error codes are below:
|
|
|
|
:``M_FORBIDDEN``:
|
|
Forbidden access, e.g. joining a room without permission, failed login.
|
|
|
|
:``M_UNKNOWN_TOKEN``:
|
|
The access token specified was not recognised.
|
|
|
|
:``M_BAD_JSON``:
|
|
Request contained valid JSON, but it was malformed in some way, e.g. missing
|
|
required keys, invalid values for keys.
|
|
|
|
:``M_NOT_JSON``:
|
|
Request did not contain valid JSON.
|
|
|
|
:``M_NOT_FOUND``:
|
|
No resource was found for this request.
|
|
|
|
:``M_LIMIT_EXCEEDED``:
|
|
Too many requests have been sent in a short period of time. Wait a while then
|
|
try again.
|
|
|
|
Some requests have unique error codes:
|
|
|
|
:``M_USER_IN_USE``:
|
|
Encountered when trying to register a user ID which has been taken.
|
|
|
|
:``M_ROOM_IN_USE``:
|
|
Encountered when trying to create a room which has been taken.
|
|
|
|
:``M_BAD_PAGINATION``:
|
|
Encountered when specifying bad pagination query parameters.
|
|
|
|
:``M_LOGIN_EMAIL_URL_NOT_YET``:
|
|
Encountered when polling for an email link which has not been clicked yet.
|
|
|
|
The C-S API typically uses ``HTTP POST`` to submit requests. This means these
|
|
requests are not idempotent. The C-S API also allows ``HTTP PUT`` to make
|
|
requests idempotent. In order to use a ``PUT``, paths should be suffixed with
|
|
``/{txnId}``. ``{txnId}`` is a unique client-generated transaction ID which
|
|
identifies the request, and is scoped to a given Client (identified by that
|
|
client's ``access_token``). Crucially, it **only** serves to identify new
|
|
requests from retransmits. After the request has finished, the ``{txnId}``
|
|
value should be changed (how is not specified; a monotonically increasing
|
|
integer is recommended). It is preferable to use ``HTTP PUT`` to make sure
|
|
requests to send messages do not get sent more than once should clients need to
|
|
retransmit requests.
|
|
|
|
Valid requests look like::
|
|
|
|
POST /some/path/here?access_token=secret
|
|
{
|
|
"key": "This is a post."
|
|
}
|
|
|
|
PUT /some/path/here/11?access_token=secret
|
|
{
|
|
"key": "This is a put with a txnId of 11."
|
|
}
|
|
|
|
In contrast, these are invalid requests::
|
|
|
|
POST /some/path/here/11?access_token=secret
|
|
{
|
|
"key": "This is a post, but it has a txnId."
|
|
}
|
|
|
|
PUT /some/path/here?access_token=secret
|
|
{
|
|
"key": "This is a put but it is missing a txnId."
|
|
}
|
|
|