OPC UA

OPC UA (Unified Architecture) is a platform-independent, service-oriented standard — formalized as IEC 62541 — for secure and reliable data exchange in industrial automation. Maintained by the OPC Foundation, it succeeds the older Windows-bound OPC “Classic” specifications and combines a rich information-modeling framework with transport and security built in. It has become a backbone protocol for connecting factory-floor equipment, control systems, and Industrial IoT (IIoT) platforms.

• Information modeling - Data isn’t just values; it carries a typed, addressable model describing what each node means and how nodes relate.
• Platform independence - Runs across operating systems and hardware, from embedded PLCs up to cloud services, replacing OPC Classic’s Windows/DCOM dependency.
• Built-in security - Authentication, authorization, encryption, and message signing are part of the standard rather than bolted on.
• Flexible transport - Supports both client/server request-response and publish/subscribe (pub/sub) patterns, the latter suited to high-volume telemetry.

For API and integration work, OPC UA is the industrial equivalent of an API contract — it is how machines and manufacturing systems expose their data in a discoverable, typed, secured way. The interesting frontier is the seam between OPC UA and web APIs: gateways increasingly bridge OPC UA information models into REST, MQTT, or event streams so that factory data can flow into cloud analytics, dashboards, and — increasingly — agents that reason over operational state. Its self-describing information model makes that translation far cleaner than scraping raw sensor values, which is why OPC UA sits at the center of most serious IIoT interoperability efforts.