SDK-Hardware Interface Notes
- Oscar Prom
- Luke Derrick
SDK HARDWARE_ONLINE & HARDWARE_OFFLINE Callbacks
The exhibit SDK emits a HARDWARE_ONLINE event with the after a hardware connection is established and successfully authenticates. It also emits a HARDWARE_OFFLINE event if the MQTT heartbeat for a particular harwareId connection isn’t received by the SDK within 20 seconds.
// gumband sdk initalization above...
// register hardware connection callbacks
gb.on(Sockets.HARDWARE_ONLINE, (payload) => {
console.log(payload);
});
gb.on(Sockets.HARDWARE_OFFLINE, (payload) => {
console.log(payload);
});Both events contain the following payload:
{
hardwareId: 123,
name: 'Exhibit Gizmo'
}SDK Hardware Authentication Scenarios
Exhibit Online |
Normal Gumband Cloud connectivity | Once the exhibit SDK has initialized, it will use hardware list (ie. connected hardware from the web UI) to know which If the exhibit SDK does not yet have the hardware list when hardware connects, those hardware connections are added to a "Waiting for Auth" queue. |
Exhibit Offline |
No Gumband Cloud connectivity | Once the exhibit SDK has initialized, it will use hardware list to allow future connections to those |
Exhibit Offline Mode |
No Gumband Cloud connectivity | Once the exhibit SDK has initialized, it will use the |
SDK “Waiting for Auth” Queue
If the exhibit SDK has not yet received the hardware list from the Gumband Cloud but is expecting to (ie. noInternetConnection: false and the SDK is initializing or the exhibit is temporarily offline), the SDK holds hardware connections in a “Waiting for Auth” queue as it waits for the hardware list. When the SDK adds connections to this queue, it doesn’t request the auth token from the connection immediately but instead just holds the connection. If the SDK doesn’t receive the hardware list from the Gumband Cloud within 10 seconds, it will disconnect the hardware connection assuming that the hardware will try to reconnect, and repeat that cycle until the Gumband Cloud connection is re-established.
How Two MQTT Connections for the Same Hardware ID Respond
If two connections try to authenticate with the same hardwareId, the SDK responds whether or not the existing connection is authenticated. If that case is true, then the new hardware connection is rejected. If the existing connection is not authenticated (ie. in the “Waiting for Auth” queue), then that connection will be severed and the new connection will be accepted.