Signal K JS Client


> A Javascript SDK for Signal K clients. Provides various abstract interfaces for discovering the Signal K server and communication via WebSocket & REST. Aims to implement all major APIs in the most recent Signal K version(s).

$3

``bash
[sudo] npm install --save @signalk/client
`

$3

`javascript
import Client, { Discovery } from '@signalk/client'
import Bonjour from 'bonjour'

let client = null

// Default options for instantiating a client:
const defaults = {
hostname: 'localhost',
port: 3000,
useTLS: true,
useAuthentication: false,
notifications: true,
autoConnect: false,
reconnect: true,
maxRetries: Infinity,
maxTimeBetweenRetries: 2500,
username: null,
password: null,
deltaStreamBehaviour: 'none',
wsKeepaliveInterval: 0
}

// Instantiate client
client = new Client({
hostname: 'demo.signalk.org',
port: 80,
useTLS: false,
reconnect: true,
autoConnect: false,
})

// Instantiate client with authentication
client = new Client({
hostname: 'demo.signalk.org',
port: 80,
useTLS: false,
rejectUnauthorized: false, // Optional, set to false only if the server has a self-signed certificate
useAuthentication: true,
reconnect: true,
autoConnect: false,
username: 'demo@signalk.org',
password: 'signalk',
})

// Discover client using mDNS
// Params: bonjour lib, search time
const bonjour = Bonjour()
const discovery = new Discovery(bonjour, 60000)

// Timeout fires when search time is up and no servers were found
discovery.on('timeout', () => console.log('No SK servers found'))

// Found fires when a SK server was found
discovery.on('found', (server) => {
if (server.isMain() && server.isMaster()) {
client = server.createClient({
useTLS: false,
useAuthentication: true,
reconnect: true,
autoConnect: true,
notifications: false,
username: 'sdk@decipher.industries',
password: 'signalk',
})
}
})

// Delta Stream over WS usage
// 1. Stream behaviour selection
client = new Client({
hostname: 'demo.signalk.org',
port: 80,
useTLS: false,
reconnect: true,
autoConnect: false,
notifications: false,
// Either "self", "all", "none", or null (see below)
// - null: no behaviour is set for the delta stream, default behaviour is used. Use this option when connecting to older devices that don't support the subscription modifiers per query request. See https://signalk.org/specification/1.4.0/doc/subscription_protocol.html.
// - "self" provides a stream of all local data of own vessel
// - "all" provides a stream of all data for all vessels
// - "none" provides no data over the stream
deltaStreamBehaviour: 'self',
// Either "all" or null.
// - null: provides no Meta data over the stream
// - "all" include Meta data of all data for all vessels
sendMeta: 'all',
// Sends an empty message to the websocket every 10 seconds when the client does not receive any more update from the server to detect if the socket is dead.
wsKeepaliveInterval: 10

})

// 2. Subscribe to specific Signal K paths
client = new Client({
hostname: 'demo.signalk.org',
port: 80,
useTLS: false,
reconnect: true,
autoConnect: false,
notifications: false,
subscriptions: [
{
context: 'vessels.*',
subscribe: [
{
path: 'navigation.position',
policy: 'instant',
},
],
},
],
})

// 3. Listen to the "delta" event to get the stream data
client.on('delta', (delta) => {
// do something with delta
})

// 4. Modify your subscription parameters. Can be a single object or an array.
client.subscribe([
{
context: 'vessels.*',
subscribe: [
{
path: 'navigation.position',
policy: 'instant',
},
],
},
])

// 5. Unsubscribe from all data paths.
client.unsubscribe()

// REST API usage
// 1. Fetch an entire group
client
.API() // create REST API client
.then((api) => api.navigation())
.then((navigationGroupResult) => {
// Do something with navigation group data
})

// 2. Fetch a specific path
client
.API() // create REST API client
.then((api) => api.get('/vessels/self/navigation/position')) // Path can be specified using dotnotation and slashes
.then((positionResult) => {
// Do something with position data
})

// 3. Fetch meta for a specific path
client
.API() // create REST API client
.then((api) => api.getMeta('vessels.self.navigation.position'))
.then((positionMetaResult) => {
// Do something with position meta data
})

// 4. Fetch the entire tree for the local vessel
client
.API() // create REST API client
.then((api) => api.self())
.then((selfResult) => {
// Do something with boat data
})

// ... check out the tests for more REST API examples
``

$3

Angular:
Signal K client for the Angular framework
signalk-client-angular

$3

- Node SK server responds with "Request updated" for access request responses. This is incorrect per spec
- Node SK server paths for access requests repsponses are not correct to spec (i.e. no /signalk/v1 prefix)