OPC UA vs MQTT
How to think about OPC UA and MQTT in industrial systems without turning the comparison into a vendor argument.
Different shapes of communication
OPC UA is commonly used for structured industrial interoperability. MQTT is commonly used for lightweight publish/subscribe messaging. Both can move industrial data, but they encourage different system designs.
OPC UA strengths
OPC UA provides a typed address space, browse/discovery features, subscriptions, rich metadata, security options, and a service model that is familiar in plant-floor integration.
MQTT strengths
MQTT is lightweight, broker-centered, and useful for decoupling publishers from consumers. It works well for edge telemetry, cloud ingestion, store-and-forward patterns, and topic-based event streams.
Practical comparison
Use OPC UA when the consuming application benefits from browsable structure, typed nodes, and device/server semantics. Use MQTT when multiple consumers need event or telemetry streams through a broker and payload conventions are clearly controlled.
The real issue
The hard part is not choosing a protocol name. The hard part is defining payload context, quality, timestamp semantics, security boundaries, ownership, and operational support.