Trait Device 

pub trait Device: Send {
    // Required methods
    fn kind(&self) -> &'static str;
    fn state(&self) -> Value;
    fn on_host_bytes(&mut self, data: &[u8], now: Millis) -> Vec<DeviceEvent>;
    fn on_control(
        &mut self,
        cmd: ControlCommand,
        now: Millis,
    ) -> Vec<DeviceEvent>;
    fn on_tick(&mut self, now: Millis) -> Vec<DeviceEvent>;
    fn next_deadline(&self) -> Option<Millis>;
    fn faults(&self) -> Vec<FaultId>;
    fn set_fault(
        &mut self,
        fault: FaultId,
        active: bool,
        opts: FaultOptions,
        now: Millis,
    ) -> Vec<DeviceEvent>;
    fn reset(&mut self, now: Millis) -> Vec<DeviceEvent>;

    // Provided methods
    fn attached_to(&self) -> Option<DeviceId> { ... }
    fn on_peripheral(
        &mut self,
        from: &DeviceId,
        signal: PeripheralSignal,
        now: Millis,
    ) -> Vec<DeviceEvent> { ... }
}

A device instance.

Sans-IO: a device is a pure state machine. Transports own all I/O and time, and pass the current time in as now. A device asks to be woken by returning a deadline from Device::next_deadline; the caller then calls Device::on_tick at or after it.

Required Methods

fn kind(&self) -> &'static str

The device kind, matching its plugin’s DevicePlugin::kind.

fn state(&self) -> Value

A JSON snapshot of the device’s state, shown in the dashboard and APIs.

fn on_host_bytes(&mut self, data: &[u8], now: Millis) -> Vec<DeviceEvent>

Host -> device bytes. A command may be split across calls.

fn on_control(&mut self, cmd: ControlCommand, now: Millis) -> Vec<DeviceEvent>

A control action from the dashboard, API, CLI or a scenario: scan, tap, close drawer.

fn on_tick(&mut self, now: Millis) -> Vec<DeviceEvent>

Time has reached (or passed) Device::next_deadline: pulses, idle job close.

fn next_deadline(&self) -> Option<Millis>

When the device next needs Device::on_tick, if ever. A deadline at or before the current time means “as soon as possible”.

fn faults(&self) -> Vec<FaultId>

The faults that apply to this instance, which may depend on its config (a serial printer has baud-mismatch, a USB one has stall). The registry rejects any other fault with RegistryError::UnsupportedFault.

fn set_fault( &mut self, fault: FaultId, active: bool, opts: FaultOptions, now: Millis, ) -> Vec<DeviceEvent>

Turns a fault on or off at now, returning what that caused, e.g. DeviceEvent::Disconnected for offline. Turning on a fault that is already on replaces its options.

fn reset(&mut self, now: Millis) -> Vec<DeviceEvent>

Back to the freshly created state at now: clears buffers, jobs and faults. Returns what that caused, e.g. DeviceEvent::Connected if the device was offline.

Provided Methods

fn attached_to(&self) -> Option<DeviceId>

The device this one is attached to as a peripheral, e.g. a cash drawer’s printer. DeviceEvent::Peripheral signals travel between attached devices.

fn on_peripheral( &mut self, from: &DeviceId, signal: PeripheralSignal, now: Millis, ) -> Vec<DeviceEvent>

A PeripheralSignal from an attached device: from a peripheral to the device it is attached to (e.g. the drawer’s open sensor), or from that device to its peripherals (e.g. a drawer-kick pulse).

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors