Discovery and Connection Establishment

Service Discovery

A Signal K server SHOULD advertise its services over mDNS/Bonjour. The server MUST use the service types

• _signalk-http._tcp for http API
• _signalk-ws._tcp for WebSocket
• _signalk-https._tcp for HTTPS API
• _signalk-wss._tcp for secure WebSocket

Furthermore a server SHOULD advertise its web interface with normal Bonjour convention _http._tcp and _https._tcp.

A sample Bonjour record output, dumped using avahi-discover:

Service data for service 'signalk-http (2)' of type '_signalk-http._tcp' in domain 'local' on 4.0:
    Host 10-1-1-40.local (10.1.1.40),
    port 8080,
    TXT data: [
        'vessel_uuid=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'version=v1.0.0',
        'vessel_name=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'vessel_mmsi=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'server=signalk-server',
        'path=/signalk'
        ]

Service data for service 'signalk-ws (2)' of type '_signalk-ws._tcp' in domain 'local' on 4.0:
    Host 10-1-1-40.local (10.1.1.40),
    port 3000,
    TXT data: [
        'vessel_uuid=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'version=v1.0.0',
        'vessel_name=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'vessel_mmsi=urn:mrn:signalk:uuid:6b0e776f-811a-4b35-980e-b93405371bc5',
        'server=signalk-server',
        'path=/signalk'
        ]

Connection Establishment

Using the information above a web client or http capable device can discover and connect to a Signal K server using the following process:

• Listen for Signal K services using Bonjour/mDns.
• Use the Bonjour record to find the REST api interface signalk-http
• Make a GET call to (eg http://10.1.1.40:8080/signalk from above)
• And get the endpoints json

{
    "endpoints": {
        "v1": {
            "version": "1.1.2",
            "signalk-http": "http://192.168.1.2/signalk/v1/api/",
            "signalk-ws": "ws://192.168.1.2:34567/signalk/v1/stream"
        }
     }
 }

• Make further REST calls for more specific data, or open a websocket connection to start streaming updates.