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Real-time Publish-Subscribe (RTPS) Wire Protocol defines a set of requirements for a wire protocol suitable for the Data Distribution Service (DDS). Primary considerations in the design of the RTPS wire protocol are: performance, configurability (tuning quality-of-service), fault-tolerance (no single points of failure), extensibility (support new transports), plug-and-play connectivity (automatic discovery), modularity, scalability, and type safety.
RTPS imposes very little requirements on the underlying transport: a connectionless service capable of sending packets best-effort is sufficient. A connection-oriented protocol can be used but is not required. The mechanisms of the underlying protocol map to the generalized notions of the RTPS Platform Independent Model (PIM).
The original DDSI-RTPS specification defined a Platform Specific Model (PSM) built upon the User Datagram Protocol (UDP) because of its simplicity, universal availability, best-effort and connectionless capabilities, predictable behavior, scalability, and multicast support.