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