Crate kinavis_signalk 

Signal K deltas in and out of the KINAVIS navigation crates.

A Signal K server merges a vessel’s NMEA 0183, NMEA 2000 and AIS into one JSON model and streams changes as deltas. This crate reads those deltas into a Picture of own vessel and every target, and a Watch assesses the picture: CPA and TCPA of each target (kinavis-traffic), and for a dangerous or developing approach the COLREGs ruling (kinavis-colregs): the encounter, who gives way and what each may do. The results go back to the server as navigation.closestApproach deltas in each target’s context and as notifications on own vessel.

Signal K units are SI: radians, metres, metres per second. The crate converts at the boundary; everything inside is KINAVIS types.

use kinavis_signalk::{parse_timestamp, Emission, Level, Watch, WatchConfig};

let mut watch = Watch::new(WatchConfig::default());
// Own vessel steering north at 6 knots (3.087 m/s)...
watch.ingest(r#"{"context":"vessels.self","updates":[{"timestamp":"2026-09-25T12:00:00Z","values":[
    {"path":"navigation.position","value":{"latitude":53.0,"longitude":5.0}},
    {"path":"navigation.courseOverGroundTrue","value":0.0},
    {"path":"navigation.speedOverGround","value":3.087}]}]}"#)?;
// ...and a motor vessel a mile and a half north and east, steering west at 6 knots.
watch.ingest(r#"{"context":"vessels.urn:mrn:imo:mmsi:244000001","updates":[{"timestamp":"2026-09-25T12:00:00Z","values":[
    {"path":"","value":{"name":"ANNA"}},
    {"path":"navigation.position","value":{"latitude":53.025,"longitude":5.04155}},
    {"path":"navigation.courseOverGroundTrue","value":4.712389},
    {"path":"navigation.speedOverGround","value":3.087},
    {"path":"navigation.state","value":"motoring"}]}]}"#)?;

let now = parse_timestamp("2026-09-25T12:00:01Z").unwrap();
let (reports, emissions) = watch.assess(now);
assert_eq!(reports[0].level, Level::Alarm);
let Some(Emission::Notification { path, value }) = emissions.last() else { panic!() };
assert_eq!(path, "notifications.navigation.closestApproach.urn:mrn:imo:mmsi:244000001");
assert_eq!(value["state"], "alarm");
assert!(value["message"].as_str().unwrap().contains("give way (Rule 15)"));

Requires the standard library: JSON, and a picture as large as the server’s.

Structs

Delta

One delta message.

Instant

The clock Watch::assess takes. Instant on one time scale, nanosecond resolution.

PathValue

A value at a path.

Picture

Every vessel seen, by context.

TargetReport

One target’s assessment.

Update

Values from one source at one time.

Utc

The clock Watch::assess takes. Coordinated Universal Time, with leap seconds.

VesselState

Last known state of one vessel.

Watch

The watch: the picture, and the level each target’s notification stands at.

WatchConfig

Watch settings: vessel decisions, with defaults for a small vessel in open water. Read from the plugin configuration, camelCase.

Enums

Category

What a vessel is, for the steering rules.

Emission

What to send to the server after an assessment.

Level

Severity of a target’s approach, as a Signal K notification state.

Constants

NOTIFICATION_PATH

Path of the notification for a target, followed by . and the target’s context without vessels..

SELF_CONTEXT

Context of own vessel in Signal K.

Functions

message

Notification text: the approach, and the ruling if there is one.

parse_timestamp

Instant of a Signal K timestamp; None if it is not one.