The SpringCard Companion Service's WebSocket delivers push notifications when specific events occurs in the system or in the connected devices. The protocol is based on JSON RPC.
Their are 4 families of events:
- Notification generated spontaneously by the Companion Service when the list of devices has changed,
- Notifications related to a user-initiated task, such as firmware upgrading, device lookup task or device network setup,
- Smart Reader related events: notification that the reader has been started or stopped, and transmission of the incoming data everytime a tag is read
- PC/SC related events: notification that the list of PC/SC readers has changed, and notification that the state of one of the PC/SC readers has changed
All the events documented in this section are broadcasted to all the client application that are currently connected to the WebSocket.
If two instances of the very same application are running simultaneously, the event is likely to be processed twice. The implementer shall be take the appropriate countermeasures accordingly.
Also, care must be taken when implementing an application that new events are likely to be added in the future. The application shall ignore gracefully all the events it does not know.