Start converting the presence module. Add Rationale admonition.

pull/977/head
Kegan Dougal 9 years ago
parent c96f02c2b0
commit 0a04672d76

@ -282,3 +282,9 @@ td[colspan]:not([colspan="1"]) {
thead {
background: #eeeeee;
}
div.admonition-rationale {
background-color: #efe;
border: 1px solid #ccc;
}

@ -1092,6 +1092,27 @@ Profiles
{{profile_http_api}}
Events on Change of Profile Information
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Because the profile display name and avatar information are likely to be used in
many places of a client's display, changes to these fields cause an automatic
propagation event to occur, informing likely-interested parties of the new
values. This change is conveyed using two separate mechanisms:
- a ``m.room.member`` event is sent to every room the user is a member of,
to update the ``displayname`` and ``avatar_url``.
- a ``m.presence`` presence status update is sent, again containing the new
values of the ``displayname`` and ``avatar_url`` keys, in addition to the
required ``presence`` key containing the current presence state of the user.
Both of these should be done automatically by the home server when a user
successfully changes their display name or avatar URL fields.
Additionally, when home servers emit room membership events for their own
users, they should include the display name and avatar URL fields in these
events so that clients already have these details to hand, and do not have to
perform extra round trips to query it.
Security
--------

@ -1,63 +1,89 @@
Presence
========
Each user has the concept of presence information. This encodes the
"availability" of that user, suitable for display on other user's clients.
Each user has presence information associated with them. This encodes the
"availability" of that user, suitable for display on other clients.
This is transmitted as an ``m.presence`` event and is one of the few events
which are sent *outside the context of a room*. The basic piece of presence
information is represented by the ``presence`` key, which is an enum of one
of the following:
which are sent *outside the context of a room*. Their presence state is
represented by the ``presence`` key, which is an enum of one of the following:
- ``online`` : The default state when the user is connected to an event
stream.
- ``unavailable`` : The user is not reachable at this time.
- ``offline`` : The user is not connected to an event stream.
- ``unavailable`` : The user is not reachable at this time e.g. they are
idle.
- ``offline`` : The user is not connected to an event stream or is
explicitly suppressing their profile information from being sent.
- ``free_for_chat`` : The user is generally willing to receive messages
moreso than default.
- ``hidden`` : Behaves as offline, but allows the user to see the client
state anyway and generally interact with client features. (Not yet
implemented in synapse).
In addition, the server maintains a timestamp of the last time it saw a
pro-active event from the user; either sending a message to a room, or
changing presence state from a lower to a higher level of availability
(thus: changing state from ``unavailable`` to ``online`` counts as a
proactive event, whereas in the other direction it will not). 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.
Events
------
{{presence_events}}
Presence HTTP API
-----------------
.. TODO-spec
- Define how users receive presence invites, and how they accept/decline them
Client behaviour
----------------
Clients can manually set/get their presence using the HTTP APIs listed below.
{{presence_http_api}}
Events on Change of Profile Information
---------------------------------------
Because the profile displayname and avatar information are likely to be used in
many places of a client's display, changes to these fields cause an automatic
propagation event to occur, informing likely-interested parties of the new
values. This change is conveyed using two separate mechanisms:
- a ``m.room.member`` event is sent to every room the user is a member of,
to update the ``displayname`` and ``avatar_url``.
- a ``m.presence`` presence status update is sent, again containing the new values of the
``displayname`` and ``avatar_url`` keys, in addition to the required
``presence`` key containing the current presence state of the user.
Both of these should be done automatically by the home server when a user
successfully changes their displayname or avatar URL fields.
Additionally, when home servers emit room membership events for their own
users, they should include the displayname and avatar URL fields in these
events so that clients already have these details to hand, and do not have to
perform extra roundtrips to query it.
Idle timeout
~~~~~~~~~~~~
Clients SHOULD implement an "idle timeout". This is a timer which fires after
a period of inactivity on the client. The definition of inactivity varies
depending on the client. For example, web implementations may determine
inactivity to be not moving the mouse for a certain period of time. When this
timer fires it should set the presence state to ``unavailable``. When the user
becomes active again (e.g. by moving the mouse) the client should set the
presence state to ``online``. A timeout value between 1 and 5 minutes is
recommended.
Server behaviour
----------------
Propagating profile information
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Because the profile display name and avatar information are likely to be used in
many places of a client's display, changes to these fields SHOULD cause an
automatic propagation event to occur, informing likely-interested parties of the
new values. One of these change mechanisms SHOULD be via ``m.presence`` events.
These events should set ``displayname`` and ``avatar_url`` to the new values
along with the presence-specific keys. This SHOULD be done automatically by the
home server when a user successfully changes their display name or avatar URL.
.. admonition:: Rationale
The intention for sending this information in ``m.presence`` is so that any
"user list" can display the *current* name/presence for a user ID outside the
scope of a room (e.g. a user page which has a "start conversation" button).
This is bundled into a single event to avoid "flickering" on this page which
can occur if you received presence first and then display name later (the
user's name would flicker from their user ID to the display name).
Last active ago
~~~~~~~~~~~~~~~
The server maintains a timestamp of the last time it saw a
pro-active event from the user. A pro-active event may be sending a message to a
room or changing presence state to a higher level of availability. Levels of
availability are defined from low to high as follows:
- ``offline``
- ``unavailable``
- ``online``
- ``free_for_chat``
Based on this list, changing state from ``unavailable`` to ``online`` counts as
a pro-active event, whereas ``online`` to ``unavailable`` does not. This
timestamp is presented via a key called ``last_active_ago`` which gives the
relative number of milliseconds since the pro-active event.
Security considerations
-----------------------
Presence information is shared with all users who share a room with the target
user. In large public rooms this could be undesirable.

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