# Sterfive: full content manifest

> Comprehensive list of canonical content URLs at sterfive.com, generated from the site's structured metadata. For a curated overview, see [/llms.txt](https://www.sterfive.com/llms.txt).
>
> Sterfive maintains NodeOPCUA (the leading open-source OPC UA stack for Node.js / TypeScript) and develops commercial OPC UA products including the Sterfive GDS Server, OPC UA Modeler, OPC UA for Node-RED, OPC UA Toolbox, and OPC UA Omni Edge. Content available in English, German, and French at `/en/`, `/de/`, `/fr/`.

## Blog: analysis, tutorials, technical deep-dives

- [Sterfive OPC UA Modeler vs UaModeler — choosing an OPC UA modelling tool](https://www.sterfive.com/en/blog/opcua-modeler-vs-uamodeler): Two very different philosophies for building OPC UA information models: UaModeler's GUI-driven approach vs Sterfive's model-as-code YAML in VS Code. An honest comparison from a team with a stake in one of them.
  - published: 2026-07-29 · category: Comparison · keywords: UaModeler, UaModeler alternative, SiOME, Siemens OPC UA Modeling Editor, UA-ModelCompiler, OPC UA Modeler comparison
- [Introducing i3x-portal: an open sandbox for OPC UA over i3X REST](https://www.sterfive.com/en/blog/i3x-portal-open-sandbox-opcua-i3x-interop): i3x-portal.sterfive.io is now open. A live OPC UA server that also answers i3X REST. Sign up for a private area, point your client at any opc.tcp URL, and start exploring. Free.
  - published: 2026-07-13 · category: Announcement · keywords: i3x-portal, i3X REST, OPC UA REST, node-i3x, OPC UA sandbox, OPC UA public server
- [Mapping OPC UA Data Types to JSON Schema: DataType, ValueRank & ArrayDimensions](https://www.sterfive.com/en/blog/opcua-datatype-valuerank-json-schema): Every OPC UA variable describes its value shape with three attributes — DataType, ValueRank and ArrayDimensions. This guide shows how node-i3x maps them, dimension for dimension, onto i3X JSON Schema, and how the special ValueRank -2 (Any) case resolves cleanly to a JSON Schema oneOf.
  - published: 2026-07-13 · category: Tutorial · keywords: OPC UA ValueRank to JSON Schema, map OPC UA data types to JSON Schema, OPC UA ArrayDimensions, OPC UA ValueRank -2, OPC UA array JSON Schema, i3X JSON Schema
- [OPC UA Role-Based Security in Practice: Implementing OPC 10000-18 with NodeOPCUA 2.174.0](https://www.sterfive.com/en/blog/opcua-role-based-security-nodeopcua-2-174-0): NodeOPCUA 2.174.0 ships a complete, spec-conformant implementation of OPC 10000-18 Role-Based Security and User Management, in open source, with one-call setup, encrypted persistence, and admin over OPC UA itself.
  - published: 2026-06-30 · category: Architecture · keywords: OPC UA Role-Based Security, OPC 10000-18, NodeOPCUA 2.174.0, OPC UA RBAC, OPC UA user management, OPC UA identity mapping
- [Connecting Siemens S7 and Modbus PLCs to OPC UA — the brownfield guide](https://www.sterfive.com/en/blog/s7-modbus-to-opc-ua): Most plants don't need new PLCs — they need their existing S7 and Modbus devices to speak OPC UA. Here's how brownfield-to-OPC-UA actually works, where hand-rolled gateways go wrong, and how to do it with one YAML file.
  - published: 2026-06-14 · updated: 2026-06-30 · category: Tutorial · keywords: S7 to OPC UA, Modbus to OPC UA, Modbus OPC UA gateway, Siemens S7 OPC UA, brownfield OPC UA, PLC to OPC UA
- [The Missing Safety Layer — and How to Bridge It (Part 3/3)](https://www.sterfive.com/en/blog/i3x-opcua-missing-safety-layer): i3X has no alarms, no method calls, no event subscriptions, and no support for dynamic address spaces. In regulated industries, this is a compliance blocker. Here's what's missing, why it matters, and how Sterfive's node-i3x bridges the gap.
  - published: 2026-06-09 · updated: 2026-06-30 · category: Architecture · keywords: i3X alarms conditions, OPC UA alarms i3X, i3X method invocation, i3X gaps limitations, i3X dynamic address space, OPC UA events i3X
- [One API Call to Rule Them All — and Its Limits (Part 2/3)](https://www.sterfive.com/en/blog/i3x-opcua-one-api-call): i3X treats every OPC UA object as a decomposable asset — one REST call returns the entire machine state. But this elegant model has cracks: missed transitions, lost counts, and no deadband control. Here's why.
  - published: 2026-06-09 · updated: 2026-06-30 · category: Architecture · keywords: i3X asset model, i3X maxDepth, i3X isComposition, OPC UA variable decomposition, i3X subscription, digital twin API
- [i3X Meets OPC UA: When REST Meets Real-Time (Part 1/3)](https://www.sterfive.com/en/blog/i3x-opcua-rest-meets-realtime): i3X and OPC UA share the same information-modeling DNA — typed hierarchies, namespaces, and VQT data atoms. This article explores why they are complementary layers, not competitors, and introduces Sterfive's node-i3x bridge.
  - published: 2026-06-09 · updated: 2026-06-30 · category: Architecture · keywords: i3X OPC UA integration, i3X REST API, OPC UA REST gateway, i3X VQT
- [i3X and OPC UA — a practical introduction](https://www.sterfive.com/en/blog/i3x-opc-ua-101): i3X is the new REST API standard from CESMII that makes OPC UA data accessible to IT developers. This 101 guide explains what i3X is, how it relates to OPC UA, and where each fits in your architecture.
  - published: 2026-06-03 · updated: 2026-06-30 · category: Architecture · keywords: i3X OPC UA, CESMII i3X, Smart Manufacturing Profile, OPC UA REST API, IT OT convergence, industrial data interoperability
- [What is an OPC UA Data Diode? One-way networks explained](https://www.sterfive.com/en/blog/opcua-data-diode): OPC UA is bidirectional by design. But some environments demand strictly one-way data flow. This article explains the Data Diode pattern — how to replicate OPC UA data across security boundaries without opening a return channel.
  - published: 2026-03-18 · updated: 2026-06-30 · category: Security · keywords: one-way OPC UA, OPC UA cyber security, OPC UA PubSub data diode, OPC UA critical infrastructure, OPC UA defense, what is an OPC UA data diode
- [What is an OPC UA GDS? Certificate management explained](https://www.sterfive.com/en/blog/what-is-opc-ua-gds): The Global Discovery Server (GDS) is the PKI backbone of OPC UA. This guide explains what it does, why you need one, and how it simplifies certificate management across your OPC UA deployment.
  - published: 2025-11-05 · updated: 2026-06-30 · category: Architecture · keywords: OPC UA certificate management, OPC UA PKI, certificate push pull, OPC UA trust list, what is an OPC UA GDS, OPC UA GDS explained
- [Building a fully compliant OPC UA server — from Companion Spec to brownfield](https://www.sterfive.com/en/blog/building-compliant-opcua-server): How to build an OPC UA server that implements Companion Specifications, exposes a rich information model, and connects to legacy PLCs and brownfield equipment — all through configuration, not code.
  - published: 2025-08-12 · updated: 2026-06-30 · category: Architecture · keywords: OPC UA server, OPC UA Companion Specification, brownfield OPC UA, OPC UA Modbus, OPC UA S7, configurable OPC UA server
- [The future of industry starts with semantic modeling](https://www.sterfive.com/en/blog/semantic-modeling-ai-industry): Before AI can transform manufacturing, machines need a common language. OPC UA Companion Specifications provide exactly that — and they are the missing foundation that separates industrial AI pilots from production-grade systems.
  - published: 2025-04-22 · updated: 2026-06-30 · category: Vision · keywords: OPC UA information modeling, Companion Specification, industrial AI, semantic modeling OPC UA, digital twin OPC UA, PackML OPC UA
- [OPC UA vs MQTT — when to use what in industrial IoT](https://www.sterfive.com/en/blog/opc-ua-vs-mqtt): OPC UA and MQTT solve different problems. This guide breaks down when to use each — and when to use both — with concrete architecture patterns for OT/IT convergence.
  - published: 2025-01-15 · updated: 2026-06-30 · category: Comparison · keywords: OPC UA vs MQTT, OPC UA MQTT comparison, industrial IoT protocol, OPC UA PubSub MQTT, OT IT convergence, Industry 4.0 protocol

## Learn: OPC UA Reference TL;DR

- [ISA-5.1 Tag Naming vs. Explicit OPC UA Modelling](https://www.sterfive.com/en/learn/opcua-reference/alias-names-isa5): Why ISA-5.1 tags and explicit OPC UA information models pull in opposite directions — and how Part 17 Alias Names lets you keep both.
  - published: 2026-08-09 · category: OPC UA Reference · keywords: ISA-5.1, instrument tag naming, OPC UA Part 17, Alias Names, OPC UA information model, brownfield modernisation
- [TL;DR — OPC UA Part 17: Alias Names](https://www.sterfive.com/en/learn/opcua-reference/alias-names): A quick-reference guide to OPC UA Part 17 (Alias Names) — FindAlias, the Aliases/TagVariables/Topics model, GDS aggregation, redundancy and failover.
  - published: 2026-08-09 · category: OPC UA Reference · keywords: OPC UA Part 17, Alias Names, FindAlias, AliasNameType, TagVariables, OPC UA GDS
- [TL;DR — ModelChangeEvents, SemanticChangeEvents and NodeVersion](https://www.sterfive.com/en/learn/opcua-reference/model-change-events): A quick-reference guide to announcing address-space changes in OPC UA — ModelChangeEvents, SemanticChangeEvents, NodeVersion, event compression, and how NodeOPCUA implements them.
  - published: 2026-08-09 · category: OPC UA Reference · keywords: ModelChangeEvent, GeneralModelChangeEventType, SemanticChangeEvent, NodeVersion, OPC UA address space, node-opcua
- [TL;DR — Reverse Connection in OPC UA](https://www.sterfive.com/en/learn/opcua-reference/reverse-connection): A quick-reference guide to OPC UA reverse connections — the ReverseHello message, firewall and NAT traversal, certificates, reconnection duties and alternatives.
  - published: 2026-08-09 · category: OPC UA Reference · keywords: OPC UA reverse connection, ReverseHello, OPC UA NAT traversal, OPC UA firewall, opc.tcp, node-opcua
- [TL;DR — OPC UA Part 12: Global Discovery Server (GDS)](https://www.sterfive.com/en/learn/opcua-reference/gds): A quick-reference guide to OPC UA Part 12 (GDS), detailing certificate management, trust list distribution, and global server registration.
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA Part 12, GDS
- [TL;DR — OPC UA Machine Vision Companion Specification](https://www.sterfive.com/en/learn/opcua-reference/machine-vision): A quick-reference guide to the OPC UA Machine Vision Companion Spec, detailing vision system integration, configuration, and results reporting.
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA Machine Vision, Companion Specification, machine vision integration, vision system
- [TL;DR — OPC UA Machinery Companion Specification](https://www.sterfive.com/en/learn/opcua-reference/machinery-jobs): A quick-reference guide to the OPC UA Machinery Companion Spec, covering machine identification, status, and job management.
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA Machinery, Companion Specification, machine identification, job management
- [TL;DR — OPC UA Information Modeling Best Practices](https://www.sterfive.com/en/learn/opcua-reference/model-best): Best practices for designing clean, high-performance, and standards-compliant OPC UA information models and companion specs.
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA modeling, information modeling, best practices, companion spec design
- [TL;DR — GDS Onboarding and Certificate Management](https://www.sterfive.com/en/learn/opcua-reference/onboarding): A quick-reference guide explaining the PUSH and PULL certificate management and onboarding flows in OPC UA Global Discovery Server (GDS).
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA onboarding, PUSH onboarding, PULL onboarding
- [TL;DR: OPC UA Part 18: Role-Based Security](https://www.sterfive.com/en/learn/opcua-reference/role-based-security): A quick-reference guide to OPC UA Part 18 (Role-Based Security), explaining identity mapping, RoleSet configurations, and local user management.
  - published: 2026-06-30 · category: OPC UA Reference · keywords: OPC UA Part 18, Role-Based Security, RBAC, OPC UA security

## Products

- [OPC UA Aggregator](https://www.sterfive.com/en/product/aggregator): A powerful OPC UA server aggregator to consolidate data from multiple OPC UA sources into a single, unified server.
  - keywords: OPC UA Aggregator, Data Consolidation, Industrial IoT, node-opcua
- [OPC UA for Node-RED](https://www.sterfive.com/en/product/for-node-red): The high-performance, secure, and fully-supported OPC UA module for professional Node-RED applications.
  - keywords: OPC UA Node-RED, nodered-contrib-opcua alternative, node-opcua
- [NodeOPCUA - The open-source OPC UA Stack](https://www.sterfive.com/en/product/node-opcua): The leading open-source OPC UA stack for Node.js, enabling rapid development of OPC UA clients, servers, and publishers/subscribers.
  - keywords: node-opcua, NodeOPCUA, OPC UA SDK, Node.js OPC UA, Open Source OPC UA
- [OPC UA Omni-Edge](https://www.sterfive.com/en/product/omni-edge): Bridge every brownfield device to OPC UA — Siemens S7, Modbus, EtherNet/IP, EtherCAT, IO-Link and more — with a single YAML file. A fully compliant edge server built on node-opcua by Sterfive.
  - keywords: OPC UA Edge Server, Industrial Edge, Brownfield Gateway, Siemens S7, Modbus TCP, EtherNet/IP
- [OPC UA Data Diode](https://www.sterfive.com/en/product/opcua-data-diode): A software-defined unidirectional data flow solution for OPC UA industrial networks. Enforce strict one-way data transmission from secure OT networks to IT/enterprise networks, preventing cyberattacks from reaching critical infrastructure.
  - keywords: OPC UA Data Diode, Unidirectional Security Gateway, OPC UA Cybersecurity, Industrial Network Security, OT IT Convergence, IEC 62443 Data Diode
- [Sterfive GDS — OPC UA Global Discovery Server](https://www.sterfive.com/en/product/opcua-gds): A production-ready OPC UA Global Discovery Server (Part 12) that automates the entire X.509 certificate lifecycle across your industrial fleet — issuance, renewal, trust list distribution and revocation, zero touch.
  - keywords: OPC UA GDS, Global Discovery Server, Certificate Management, PKI, PULL Certificate Management, PUSH Certificate Management
- [OPC UA Modeler](https://www.sterfive.com/en/product/opcua-modeler): A Low Code Tool to design and generate OPC UA information models (nodesets) with ease and precision.
  - keywords: OPC UA Modeler, Nodeset Editor, OPC UA Information Model, XML Nodeset, node-opcua
- [Sterfive's OPC UA Toolbox](https://www.sterfive.com/en/product/toolbox): A comprehensive suite of professional tools for OPC UA developers and integrators to test, diagnose, and troubleshoot their OPC UA applications.
  - keywords: OPC UA Tools, OPC UA Client, OPC UA Server Simulator, OPC UA Testing, node-opcua

## Services

- [OPC UA Consulting & Expertise](https://www.sterfive.com/en/services/consulting): OPC UA architecture, information modeling, interoperability audits, security and performance consulting — from the engineers who maintain node-opcua and sit on the OPC Foundation.
  - keywords: OPC UA consulting, OPC UA architecture review, OPC UA information modeling, OPC UA interoperability audit, OPC UA security consulting, IEC 62443 OPC UA
- [Custom OPC UA Development](https://www.sterfive.com/en/services/development): Custom OPC UA servers, clients, gateways and product integrations — built on node-opcua by the team that wrote it. Production-grade, tested against real PLCs.
  - keywords: Custom OPC UA development, OPC UA server development, OPC UA client development, S7 to OPC UA gateway, Modbus to OPC UA bridge, MQTT to OPC UA
- [node-opcua Professional Support](https://www.sterfive.com/en/services/support): Running node-opcua in production? Get a direct line to the engineers who wrote it — priority fixes, security and CRA readiness, and an SLA.
  - keywords: node-opcua support, OPC UA SLA, OPC UA CRA compliance, commercial OPC UA support, node-opcua professional support, OPC UA security advisory
- [OPC UA Training Services](https://www.sterfive.com/en/services/training): Expert-led OPC UA training courses for engineers, developers, and project managers in industrial automation.
  - keywords: OPC UA Training, OPC UA Courses, Industrial Training, OPC UA Expert Training

## Key static pages

- [Home](https://www.sterfive.com/en): Sterfive overview.
- [About Sterfive](https://www.sterfive.com/en/company/about-sterfive): Company.
- [Our team](https://www.sterfive.com/en/company/our-team): Founder Etienne Rossignon (NodeOPCUA maintainer) and engineering team.
- [Contact](https://www.sterfive.com/en/contact)
- [Training](https://www.sterfive.com/en/training): OPC UA developer / architect training.
- [Shop: OPC UA for Node-RED](https://www.sterfive.com/en/shop/opcua-for-nodered)
- [Shop: OPC UA Modeler](https://www.sterfive.com/en/shop/opcua-modeler)
- [Shop: OPC UA Toolbox](https://www.sterfive.com/en/shop/opcua-toolbox)
- [Shop: OPC UA Omni Edge](https://www.sterfive.com/en/shop/opcua-omni-edge)

## Authoritative external resources

- [github.com/node-opcua/node-opcua](https://github.com/node-opcua/node-opcua): Source code and releases for NodeOPCUA.
- [node-opcua.github.io](https://node-opcua.github.io): NodeOPCUA documentation.
- [reference.opcfoundation.org](https://reference.opcfoundation.org): Official OPC UA specifications.