Struct DatagramHeader 

pub struct DatagramHeader {
    pub track_alias: VarInt,
    pub group_id: VarInt,
    pub object_id: VarInt,
    pub publisher_priority: u8,
    pub extension_count: VarInt,
    pub extensions: Vec<u8>,
    pub object_status: ObjectStatus,
    pub payload_length: VarInt,
}

Datagram header with payload (draft-08, type 0x01).

Encoding (after type varint): track_alias(vi), group_id(vi), object_id(vi), publisher_priority(u8), extension_count(vi), [extensions…], payload_length(vi), if payload_length == 0: object_status(vi), payload bytes

Fields

track_alias: VarInt

Track alias identifying the subscription.

group_id: VarInt

Group identifier.

object_id: VarInt

Object identifier within the group.

publisher_priority: u8

Publisher priority for delivery ordering.

extension_count: VarInt

Number of extensions.

extensions: Vec<u8>

Raw extension bytes (opaque).

object_status: ObjectStatus

Status of this object.

payload_length: VarInt

Length of the object payload in bytes.

Implementations

impl DatagramHeader

pub fn encode(&self, buf: &mut impl BufMut)

Encode the datagram header into the buffer.

The declared payload length is taken as the authority on framing: the status field is written exactly when that length is zero, because that is the condition under which the OBJECT_DATAGRAM layout in draft-08 Section 8.2 carries one. That is what makes this infallible — and what makes it lossy when the struct disagrees with itself. An object_status set alongside a non-zero payload_length is discarded here without a word. Prefer Self::encode_checked, which refuses that combination instead of resolving it.

pub fn encode_checked(&self, buf: &mut impl BufMut) -> Result<(), CodecError>

Encode the datagram header, refusing a status the framing cannot carry.

A datagram states its Object Status only when its Object Payload Length is zero. With a non-zero length there is no status field on the wire, so an object_status of anything but ObjectStatus::Normal has nowhere to go: Self::encode drops it and the datagram parses back as an ordinary payload object. An End of Group marker written that way does not arrive late or malformed — it does not arrive at all, and the receiver sees a normal object in its place.

That pair is also the frame draft-08 Section 8.1.1.1 forbids outright: “Any object with a status code other than zero MUST have an empty payload.” So the refusal here is not merely about what this encoder can express; there is no conforming datagram to express.

ObjectStatus::Normal beside a payload is not that case and is accepted. It is the status every payload-bearing object has under the rule above, and the one the encoding elides, so stating it asks for exactly the bytes leaving it out asks for and nothing is lost.

Errors with CodecError::InvalidField on the lossy combination, before any byte is written, so a refused header leaves buf untouched.

pub fn decode(buf: &mut impl Buf) -> Result<Self, CodecError>

Decode a datagram header from the buffer.

Trait Implementations

impl Clone for DatagramHeader

fn clone(&self) -> DatagramHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DatagramHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for DatagramHeader

impl PartialEq for DatagramHeader

fn eq(&self, other: &DatagramHeader) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for DatagramHeader