Struct zenoh_protocol::proto::Frame

pub struct Frame {
    pub ch: Channel,
    pub sn: ZInt,
    pub payload: FramePayload,
}

NOTE: 16 bits (2 bytes) may be prepended to the serialized message indicating the total lenght in bytes of the message, resulting in the maximum lenght of a message being 65_536 bytes. This is necessary in those stream-oriented transports (e.g., TCP) that do not preserve the boundary of the serialized messages. The length is encoded as little-endian. In any case, the lenght of a message must not exceed 65_535 bytes.

7 6 5 4 3 2 1 0 +-+-+-+-+-+-+-+-+ |E|F|R| FRAME | +-+-+-+-+-------+ ~ SN ~ +---------------+ ~ FramePayload ~ -- if F==1 then the payload is a fragment of a single Zenoh Message, a list of complete Zenoh Messages otherwise. +---------------+

• if R==1 then the FRAME is sent on the reliable channel, best-effort otherwise.
• if F==1 then the FRAME is a fragment.
• if E==1 then the FRAME is the last fragment. E==1 is valid iff F==1.

NOTE: Only one bit would be sufficient to signal fragmentation in a IP-like fashion as follows: - if F==1 then this FRAME is a fragment and more fragment will follow; - if F==0 then the message is the last fragment if SN-1 had F==1, otherwise it's a non-fragmented message. However, this would require to always perform a two-steps de-serialization: first de-serialize the FRAME and then the Payload. This is due to the fact the F==0 is ambigous w.r.t. detecting if the FRAME is a fragment or not before SN re-ordering has occured. By using the F bit to only signal whether the FRAME is fragmented or not, it allows to de-serialize the payload in one single pass when F==0 since no re-ordering needs to take place at this stage. Then, the F bit is used to detect the last fragment during re-ordering.

Fields

ch: Channel

sn: ZInt

payload: FramePayload

Trait Implementations

impl Clone for Frame

fn clone(&self) -> Frame

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Frame

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

Formats the value using the given formatter.

impl PartialEq<Frame> for Frame

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl StructuralPartialEq for Frame