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OPC UA Fundamentals

In one sentence, OPC UA defines a framework for object-oriented information models that live in an OPC UA server together with a protocol that clients use to interact with those models over the network.

This section introduces the core concepts of OPC UA:

  • Protocol — the binary protocol over TCP, and the three nested layers of a connection.
  • Services — the service sets every interaction is expressed with.
  • Information Modelling — nodes, references, and the address space as a graph.
  • DataType — the type system's extensibility point, and how values are encoded.
  • Namespace — URIs, indices, and why ns0 and ns1 are special.
  • Nodeset Files & Companion Specs — how models are packaged and published.

For the full specification see the OPC UA standard at https://reference.opcfoundation.org/.