[−][src]Crate ruma_events

Crate ruma_events contains serializable types for the events in the Matrix specification that can be shared by client and server code.

All data exchanged over Matrix is expressed as an event. Different event types represent different actions, such as joining a room or sending a message. Events are stored and transmitted as simple JSON structures. While anyone can create a new event type for their own purposes, the Matrix specification defines a number of event types which are considered core to the protocol, and Matrix clients and servers must understand their semantics. ruma_events contains Rust types for each of the event types defined by the specification and facilities for extending the event system for custom event types.

Event types

ruma_events includes a Rust enum called EventType, which provides a simple enumeration of all the event types defined by the Matrix specification. Matrix event types are serialized to JSON strings in reverse domain name notation, although the core event types all use the special "m" TLD, e.g. m.room.message. EventType also includes a variant called Custom, which is a catch-all that stores a string containing the name of any event type that isn't part of the specification. EventType is used throughout ruma_events to identify and differentiate between events of different types.

Event traits

Matrix defines three "kinds" of events:

Events, which are arbitrary JSON structures that have two required keys:
- type, which specifies the event's type
- content, which is a JSON object containing the "payload" of the event
Room events, which are a superset of events and represent actions that occurred within the context of a Matrix room. They have at least the following additional keys:
- event_id, which is a unique identifier for the event
- room_id, which is a unique identifier for the room in which the event occurred
- sender, which is the unique identifier of the Matrix user who created the event
- Optionally, unsigned, which is a JSON object containing arbitrary additional metadata that is not digitally signed by Matrix homeservers.
State events, which are a superset of room events and represent persistent state specific to a room, such as the room's member list or topic. Within a single room, state events of the same type and with the same "state key" will effectively "replace" the previous one, updating the room's state. They have at least the following additional keys:
- state_key, a string which serves as a sort of "sub-type." The state key allows a room to persist multiple state events of the same type. You can think of a room's state events as being a HashMap where the keys are the tuple (event_type, state_key).
- Optionally, prev_content, a JSON object containing the content object from the previous event of the given (event_type, state_key) tuple in the given room.

ruma_events represents these three event kinds as traits, allowing any Rust type to serve as a Matrix event so long as it upholds the contract expected of its kind.

Core event types

ruma_events includes Rust types for every one of the event types in the Matrix specification. To better organize the crate, these types live in separate modules with a hierarchy that matches the reverse domain name notation of the event type. For example, the m.room.message event lives at ruma_events::room::message::MessageEvent. Each type's module also contains a Rust type for that event type's content field, and any other supporting types required by the event's other fields. All concrete event types in ruma_events are serializable and deserializable using the Serde serialization library.

Custom events

Although any Rust type that implements Event, RoomEvent, or StateEvent can serve as a Matrix event type, ruma_events also includes a few convenience types for representing events that are not convered by the spec and not otherwise known by the application. CustomEvent, CustomRoomEvent, and CustomStateEvent are simple implementations of their respective event traits whose content field is simply a serde_json::Value value, which represents arbitrary JSON.

Collections

With the trait-based approach to events, it's easy to write generic collection types like Vec<Box<R: RoomEvent>>. However, there are APIs in the Matrix specification that involve heterogeneous collections of events, i.e. a list of events of different event types. Because Rust does not have a facility for arrays, vectors, or slices containing multiple concrete types, ruma_events provides special collection types for this purpose. The collection types are enums which effectively "wrap" each possible event type of a particular event "kind."

Because of the hierarchical nature of event kinds in Matrix, these collection types are divied into two modules, ruma_events::collections::all and ruma_events::collections::only. The "all" versions include every event type that implements the relevant event trait as well as more specific event traits. The "only" versions include only the event types that implement "at most" the relevant event trait.

For example, the ruma_events::collections::all::Event enum includes m.room.message, because that event type is both an event and a room event. However, the ruma_events::collections::only::Event enum does not include m.room.message, because m.room.message implements a more specific event trait than Event.

Modules

call	Modules for events in the m.call namespace.
collections	Enums for heterogeneous collections of events.
direct	Types for the m.direct event.
presence	Types for the m.presence event.
receipt	Types for the m.receipt event.
room	Modules for events in the m.room namespace.
stripped	"Stripped-down" versions of the core state events.
tag	Types for the m.tag event.
typing	Types for the m.typing event.

Structs

CustomEvent	A custom basic event not covered by the Matrix specification.
CustomRoomEvent	A custom room event not covered by the Matrix specification.
CustomStateEvent	A custom state event not covered by the Matrix specification.
ParseError	An error when attempting to convert a string to an enum that only accepts certain values.

Enums

EventType

The type of an event.

Traits

Event	A basic event.
RoomEvent	An event within the context of a room.
StateEvent	An event that describes persistent state about a room.