Module metadata

Structs§

Parameter: A metadata parameter that can be sent as part of output messages.

FIN: Metadata key marking the last chunk of a segment (true on final chunk).
FLUSH: Metadata key to discard older queued messages on this input (true to flush).
FRAMING: Metadata key indicating the wire framing of the data payload. When set to "arrow-ipc", the payload is an Arrow IPC stream.
FRAMING_ARROW_IPC: Value for FRAMING indicating Arrow IPC stream framing.
GOAL_ID: Metadata key for identifying an action goal across feedback/result messages.
GOAL_STATUS: Metadata key for the completion status of an action goal.
GOAL_STATUS_ABORTED: Goal was aborted by the server.
GOAL_STATUS_CANCELED: Goal was canceled by the client.
GOAL_STATUS_SUCCEEDED: Goal completed successfully.
REQUEST_ID: Metadata key for correlating a service request with its response.
SCHEMA_HASH: Metadata key carrying the FNV-1a hash (as an i64) of the Arrow IPC schema for a zenoh data message. Present on schema-once messages so a receiver can tell which primed decoder a schema-less batch belongs to and detect schema changes. Absent on messages a receiver should decode as a standalone full stream (large/SHM and daemon-path payloads).
SEGMENT_ID: Metadata key for the logical segment within a session (e.g. one utterance).
SEQ: Metadata key for chunk sequence number within a segment.
SESSION_ID: Metadata key identifying the conversation/session.

carries_pattern_correlation: Returns true if the given parameters carry any pattern-correlation key (REQUEST_ID, GOAL_ID, or GOAL_STATUS).
fnv1a: FNV-1a-64 hash with a fixed seed (cross-process deterministic). Used to fingerprint an Arrow IPC schema block so a schema-less batch can be matched to the schema it was encoded against (see SCHEMA_HASH). The producer node, the consumer node, and the daemon’s dora topic debug path all hash the same schema-block bytes with this function, so the value must stay identical across crates — keep this the single source of truth.
get_bool_param: Extract a bool parameter from metadata, returning None if missing or not a Parameter::Bool.
get_integer_param: Extract an integer parameter from metadata, returning None if missing or not a Parameter::Integer.
get_string_param: Extract a string parameter from metadata, returning None if missing or not a Parameter::String.
strip_internal_parameters: Remove internal wire-protocol keys (SCHEMA_HASH, FRAMING) from a parameter map. Call this at every wire→user boundary: the keys are meaningless after decode, and a stale SCHEMA_HASH forwarded from an input’s metadata into send_output parameters (a standard pattern, e.g. replay) would ride onto outputs that don’t overwrite it, making receivers hash-mismatch and silently drop them (dora-rs/dora#2366 review).

MetadataParameters: Additional metadata that can be sent as part of output messages.