OPC UA protocol vs MQTT protocol

Question

I would like to compare OPC UA vs MQTT on basis of the general characteristics of both the protocols such as Overhead (Packets), Security, Information modeling and Reliability.

Answer 1

OPC UA and MQTT are orthogonal because they try to solve different problems.

The OPC UA WG is currently developing a PubSub extension OPC UA that specifies how OPC UA payloads can be sent over MQTT, AMQP or XMPP.

One of the biggest problems with MQTT is the format of the payload is left to the application which means you have no real inter-operability between applications that have not been specifically coded to work with each other. The OPC UA PubSub extension addresses this limitation by defining a syntax for OPC UA payloads.