DDS is a data-centric middleware: participants publish and subscribe to typed topics in a shared global data space, and the implementation discovers peers automatically and delivers samples directly, with no broker in the path. Dozens of configurable QoS policies cover reliability, durability, deadlines, liveliness and ownership, which lets a system state its timing and delivery needs explicitly.
That makes DDS the choice where latency and determinism matter more than simplicity: ROS 2 uses it as its communication layer, and it is common in autonomous vehicles, medical devices, naval and air traffic systems. The trade-offs are complexity, a larger footprint than MQTT and a model designed for a LAN rather than devices scattered behind NATs on the internet. It can also connect to OPC UA through a defined gateway specification for industrial use.
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