Module submessages 

RTPS Submessages

Minimal subset for BEST_EFFORT QoS:

• DATA: User data
• HEARTBEAT: Writer liveliness
• ACKNACK: Reader acknowledgment (optional for RELIABLE)

Structs

AckNack

ACKNACK submessage

Data

DATA submessage

Heartbeat

HEARTBEAT submessage

SubmessageFlags

Submessage flags (1 byte)

SubmessageHeader

Submessage header (4 bytes)

Enums

Submessage

Generic submessage enum

SubmessageKind

Submessage kind (1 byte)