Trait ServerHandler 

pub trait ServerHandler {
    type Error: NrcError;

    // Required methods
    fn read_did(&self, did: u16, buf: &mut [u8]) -> Result<usize, Self::Error>;
    fn write_did(&mut self, did: u16, data: &[u8]) -> Result<(), Self::Error>;
    fn ecu_reset(&mut self, reset_type: u8) -> Result<(), Self::Error>;

    // Provided methods
    fn routine_control(
        &mut self,
        _routine_id: u16,
        _sub_function: u8,
        _data: &[u8],
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
    fn communication_control(
        &mut self,
        _control_type: u8,
        _comm_type: u8,
    ) -> Result<usize, Self::Error> { ... }
    fn request_download(
        &mut self,
        _memory_address: &[u8],
        _memory_size: &[u8],
        _compression_method: u8,
        _encrypting_method: u8,
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
    fn io_control(
        &mut self,
        _did: u16,
        _parameter: u8,
        _control_state: &[u8],
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
    fn transfer_data(
        &mut self,
        _block_sequence_counter: u8,
        _data: &[u8],
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
    fn request_transfer_exit(
        &mut self,
        _parameter_record: &[u8],
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
    fn request_file_transfer(
        &mut self,
        _operation: u8,
        _path: &[u8],
        _buf: &mut [u8],
    ) -> Result<usize, Self::Error> { ... }
}

Application-level hook trait for UDS service handling.

The server state machine calls these hooks when a valid, session-permitted, security-cleared request arrives that requires application data or action. The server handles all protocol framing, session management, security access state, and periodic scheduling internally - the handler only sees the decoded parameters.

Required vs Optional Hooks

Required hooks have no default implementation - the compiler enforces them. Optional hooks default to NRC 0x11 (Service Not Supported). Override only the services your ECU actually supports.

Buffer Convention

Response data is written into the provided buf slice. The return value is the number of valid bytes written. The server sends only buf[..len].

Error Mapping

type Error must implement NrcError + Into<u8>. The server converts handler errors directly to NRC bytes in the negative response.

Required Associated Types

type Error: NrcError

Required Methods

fn read_did(&self, did: u16, buf: &mut [u8]) -> Result<usize, Self::Error>

Reads the value of a data identifier into buf.

Called for ReadDataByIdentifier (0x22) and periodic scheduling (0x2A). Returns the number of bytes written into buf.

fn write_did(&mut self, did: u16, data: &[u8]) -> Result<(), Self::Error>

Writes a value to a data identifier.

Called for WriteDataByIdentifier (0x2E).

fn ecu_reset(&mut self, reset_type: u8) -> Result<(), Self::Error>

Executes an ECU Reset.

Called for EcuReset (0x11). Reset Types: 0x01 Hard Reset, 0x02 KeyOffOnReset, 0x03 SoftReset. The positive response is sent before this hook is called.

Provided Methods

fn routine_control( &mut self, _routine_id: u16, _sub_function: u8, _data: &[u8], _buf: &mut [u8], ) -> Result<usize, Self::Error>

Executes a routine control operation.

Called for Routine Control (0x31). Sub-Functions: 0x01 Start Routine, 0x02 Stop Routine, 0x03 Request Routine Results.

Return the number of bytes written into buf.

fn communication_control( &mut self, _control_type: u8, _comm_type: u8, ) -> Result<usize, Self::Error>

Controls communication on a network channel.

Called for CommunicationControl (0x28)

fn request_download( &mut self, _memory_address: &[u8], _memory_size: &[u8], _compression_method: u8, _encrypting_method: u8, _buf: &mut [u8], ) -> Result<usize, Self::Error>

Initiates a data download session.

Called for RequestDownload (0x34).

Returns max block length encoded in buf.

fn io_control( &mut self, _did: u16, _parameter: u8, _control_state: &[u8], _buf: &mut [u8], ) -> Result<usize, Self::Error>

Controls an input or output signal

Called for InputOutputControlByIdentifier (0x2F).

Returns the number of bytes written into buf.

fn transfer_data( &mut self, _block_sequence_counter: u8, _data: &[u8], _buf: &mut [u8], ) -> Result<usize, Self::Error>

Transfers a block of data.

Called for TransferData (0x36).

Returns the number of bytes written into buf.

fn request_transfer_exit( &mut self, _parameter_record: &[u8], _buf: &mut [u8], ) -> Result<usize, Self::Error>

Finalises a data transfer session.

Called for RequestTransferExit (0x37).

Returns the number of bytes written into buf.

fn request_file_transfer( &mut self, _operation: u8, _path: &[u8], _buf: &mut [u8], ) -> Result<usize, Self::Error>

Initiates a file transfer operation.

Called for RequestFileTransfer (0x38).

Returns the number of bytes written into buf.

Implementors