open62541 implentation

[roblahnst]

I’d like to submit a feature request regarding OPC UA support in Mongoose.

Motivation

In a number of embedded/industrial applications, OPC UA is a common requirement (integration into PLC/SCADA/MES environments, standardized information modeling, and interoperable data access). Today, MQTT is often a good fit for telemetry, but it doesn’t cover the same use cases as OPC UA (client/server, browseable information model, method calls, etc.).

For constrained targets (e.g., STM32-class MCUs), the open62541 stack is a well-established, permissively licensed OPC UA implementation and is widely used in embedded settings.

Requested feature

Add an officially supported option to use OPC UA via open62541 within Mongoose-based applications, as an alternative (or complement) to MQTT.

Concretely, this could be delivered as one of the following:

1. Integration module / example: A maintained reference integration showing how to run an open62541 server (and/or client) alongside the Mongoose event loop, including best practices for non-blocking operation.
2. Event-loop friendly API: Helpers to drive open62541’s periodic work from Mongoose timers/polling, so that the OPC UA stack can run cooperatively with Mongoose networking (no dedicated thread required).
3. Build & portability support: Guidance and configuration for common embedded toolchains (GCC/Clang, STM32CubeIDE), including static builds and minimal feature sets to reduce footprint.

Technical notes / expectations

• Non-blocking design: Ideally, the integration would avoid long blocking calls and allow open62541 iteration via mg_timer or a similar mechanism.
• TLS considerations: If TLS is used, alignment with Mongoose TLS abstractions (where feasible) would be helpful, especially for constrained platforms.
• Resource footprint: A “minimal embedded profile” (reduced nodeset, minimal security policies, etc.) would be valuable.
• Examples: An example exposing a few variables (e.g., floats/ints) and updating them periodically would help adoption, as would a simple client example.

Why this is valuable for Mongoose

• Broadens Mongoose’s appeal in industrial/OT contexts where OPC UA is requested by customers.
• Provides a clear migration path for users who currently build custom glue code between Mongoose and open62541.
• Positions Mongoose as a more complete connectivity layer (MQTT + OPC UA), especially on embedded devices.

[scaprile]

What you expect is basically what we always do.
We have no current interest in this, if you have a compelling application you might want to contact us at Support and discuss a commercial agreement.
Thank you