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diff --git a/docs/client-server/model/terminology.rst b/docs/client-server/model/terminology.rst new file mode 100644 index 0000000000..cc6e6760ac --- /dev/null +++ b/docs/client-server/model/terminology.rst @@ -0,0 +1,86 @@ +=========== +Terminology +=========== + +A list of definitions of specific terminology used among these documents. +These terms were originally taken from the server-server documentation, and may +not currently match the exact meanings used in other places; though as a +medium-term goal we should encourage the unification of this terminology. + + +Terms +===== + +Backfilling: + The process of synchronising historic state from one home server to another, + to backfill the event storage so that scrollback can be presented to the + client(s). (Formerly, and confusingly, called 'pagination') + +Context: + A single human-level entity of interest (currently, a chat room) + +EDU (Ephemeral Data Unit): + A message that relates directly to a given pair of home servers that are + exchanging it. EDUs are short-lived messages that related only to one single + pair of servers; they are not persisted for a long time and are not forwarded + on to other servers. Because of this, they have no internal ID nor previous + EDUs reference chain. + +Event: + A record of activity that records a single thing that happened on to a context + (currently, a chat room). These are the "chat messages" that Synapse makes + available. + [[NOTE(paul): The current server-server implementation calls these simply + "messages" but the term is too ambiguous here; I've called them Events]] + +PDU (Persistent Data Unit): + A message that relates to a single context, irrespective of the server that + is communicating it. PDUs either encode a single Event, or a single State + change. A PDU is referred to by its PDU ID; the pair of its origin server + and local reference from that server. + +PDU ID: + The pair of PDU Origin and PDU Reference, that together globally uniquely + refers to a specific PDU. + +PDU Origin: + The name of the origin server that generated a given PDU. This may not be the + server from which it has been received, due to the way they are copied around + from server to server. The origin always records the original server that + created it. + +PDU Reference: + A local ID used to refer to a specific PDU from a given origin server. These + references are opaque at the protocol level, but may optionally have some + structured meaning within a given origin server or implementation. + +Presence: + The concept of whether a user is currently online, how available they declare + they are, and so on. See also: doc/model/presence + +Profile: + A set of metadata about a user, such as a display name, provided for the + benefit of other users. See also: doc/model/profiles + +Room ID: + An opaque string (of as-yet undecided format) that identifies a particular + room and used in PDUs referring to it. + +Room Alias: + A human-readable string of the form #name:some.domain that users can use as a + pointer to identify a room; a Directory Server will map this to its Room ID + +State: + A set of metadata maintained about a Context, which is replicated among the + servers in addition to the history of Events. + +User ID: + A string of the form @localpart:domain.name that identifies a user for + wire-protocol purposes. The localpart is meaningless outside of a particular + home server. This takes a human-readable form that end-users can use directly + if they so wish, avoiding the 3PIDs. + +Transaction: + A message which relates to the communication between a given pair of servers. + A transaction contains possibly-empty lists of PDUs and EDUs. + |