724ae71f8a
Fixes #4137. ## The problem `NodeState.Initialize(ISystemContext, NodeState)` copies a node. Every child it materialises through `CreateChild` gets a per-instance NodeId from `ISystemContext.NodeIdFactory`, and is then initialised from its source on the very next statement - which overwrites that NodeId. The assignment is therefore *always* discarded: it only burns identifiers, and permanently leaks them for factories that track outstanding allocations. Booting the Robotics node manager left ten reservations behind that every later allocation skipped. #4123 fixed the symptom by hiding the factory for the duration of the copy, wrapping the context in one that reports `NodeIdFactory` as `null`. The review objection was fair: a context that lies about one property is hard to reason about, and it only works because that property is allowed to be null. ## What this does States the intent instead of faking the environment. NodeId assignment is now an argument of the two members that materialise children: ```csharp public virtual BaseInstanceState? CreateChild( ISystemContext context, QualifiedName browseName, bool assignInstanceNodeIds = true); protected virtual BaseInstanceState? FindChild( ISystemContext context, QualifiedName browseName, bool createOrReplace, BaseInstanceState? replacement, bool assignInstanceNodeIds = true); ``` A copy passes `assignInstanceNodeIds: false` and every node type - generated or hand-written - sees the real context. There is no capability property, no wrapper, and no second overload to keep in sync. `MethodState`, `BaseDataVariableState` and the source generator template each collapse to a single `FindChild` override that threads the argument into its `CreateOrReplace<Child>` helpers. ## Breaking change The four argument `FindChild` and the two argument `CreateChild` virtuals are gone. - **Call sites are unaffected.** The new parameter defaults to `true`, so `CreateChild(context, browseName)` and `FindChild(context, browseName, true, null)` keep compiling and keep the 1.5.378 behaviour. - **Overrides must add the parameter.** A node manager that overrides either member gets `CS0115` until it does. The compiler points at every site; `docs/migrate/2.0.x/node-states.md` shows the before/after. This is deliberate, per review: the stack ships all base types, and types generated from a model are regenerated for 2.0 anyway. ## Also fixed `MethodState.FindChild` returned `OutputArguments` when asked for `InputArguments` with `createOrReplace: false` - a pre-existing bug in the method being restructured. Covered by `FindChildReturnsTheRequestedArgumentsProperty`. ## Validation - Full `dotnet build UA.slnx`: **0 errors, 0 warnings**. - `Opc.Ua.Types.Tests`, `Opc.Ua.SourceGeneration.Core.Tests`, `Opc.Ua.SourceGeneration.Tests`, `Opc.Ua.Di.Tests`, `Opc.Ua.Robotics.Tests` - all passing. - Each new regression test was checked to fail without its corresponding fix. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> Copilot-Session: 8cbb8cd0-f0cb-4ab0-bea2-6202fbf69485 Copilot-Session: f45109d9-59cb-4ffd-a4f7-16e1ea449ae4
OPC UA .NET Standard Stack
🆕 This is version 2.0 of the OPC UA .NET Standard Stack (current
master).Looking for the supported 1.x release? It lives on the
master378branch (last release:1.5.378). All new feature work happens here onmaster;master378continues to receive security and critical-bug fixes for the 1.x line.
The official OPC Foundation reference implementation of OPC UA for .NET — a certified, cross-platform stack with client, server, PubSub, GDS, complex types, and source-generated tooling. Used in production across industrial control, manufacturing, energy, and IoT systems.
📦 What it is
- A full-stack OPC UA implementation — Core / Client / Server / PubSub / GDS / LDS / Complex Types / Device Integration / Positioning libraries built on .NET, with UA-TCP and HTTPS transports.
- Cross-platform — runs on .NET 10, .NET 9, .NET 8 (LTS), .NET Framework 4.8, and .NET Standard 2.1; ships Native-AOT-friendly assemblies.
- Certified for compliance — the reference server has been certified through an OPC Foundation Certification Test Lab and is continuously verified against the latest Compliance Test Tool (CTT).
- Companion-spec coverage — Part 9 (Alarms & Conditions), Part 11 (Historical Access), Part 13 (Aggregates), Part 16 (State Machines), Part 17 (Alias Names), Part 18 (Role Management), Part 20 (File Transfer), Part 100 (Device Integration), Parts 210/211 (Relative Spatial Location and Global Positioning), OPC-10030 (ISA-95 Common Model) with OPC-10031-4 Job Control V1/V2, OPC 10100-1 (WoT Connectivity), OPC 40001-1 (Industrial Automation), OPC 40010-1 (Robotics).
- Modern developer surface — first-class
Microsoft.Extensions.DependencyInjectionhosting (services.AddOpcUa()), fluent server + client builders, source-generated NodeManagers and DataTypes, and an MCP server so LLMs / Copilot can drive an OPC UA client.
For the full feature breakdown see OPC UA Profiles and Facets and the What's New in 2.0 tour.
🚀 Getting started
You need the .NET 10 SDK to build the repo. From the repository root:
dotnet restore UA.slnx
dotnet build UA.slnx
For the supported target frameworks and platform notes see
the Developer Guide. The official NuGet packages
are published to nuget.org under the OPCFoundation.NetStandard
prefix — the meta package
OPCFoundation.NetStandard.Opc.Ua
pulls in everything, or pick the split
OPCFoundation.NetStandard.Opc.Ua.Core / .Client / .Server /
.Bindings.Https packages directly. Preview builds for every successful
master build are available in the
Azure DevOps opcua-preview feed.
Sample applications
Each sample has its own README.md with build and run instructions.
Reference applications
- Console Reference Server — the certified reference server (with Quickstarts, CTT, and Mono configs). Also ships as a Docker container.
- Console Reference Client — cross-platform reference client demonstrating sessions, subscriptions, browsing, and method calls.
- Console LDS Server — a standalone
Local Discovery Server built on
Opc.Ua.Lds.Server.
PubSub samples
- Console Reference PubSub Client —
one executable with
publisher,subscriber, andexternal(external-server adapter) modes across the supported transport profiles.
Minimal / Device-Integration samples
- Minimal Calc Server — minimal server built on the source-generated NodeManager pipeline (Calc model).
- Minimal Boiler Server — minimal Boiler-model server with the fluent state-machine builder; Native-AOT publishable.
- Pump Device Integration Server —
minimal Device Integration (Part 100) server using
Opc.Ua.Di.Server's fluent builder. - Minimal Robot Server — OPC 40010 Robotics with independently configurable RSL/GPOS motion and live OpenUSD transforms.
- Minimal ISA-95 Server — minimal server hosting the OPC-10030 ISA-95 Common Model together with OPC-10031-4 Job Control V1 and V2, using the typed common-model builder and the in-memory Job Control provider.
More sample projects are maintained in the companion OPC UA .NET Samples repository.
Developer tools
- OPC UA MCP Server — installable .NET tool and container that exposes OPC UA client operations as MCP tools for LLMs and Copilot.
🔧 Migrating from 1.5.378 to 2.0
The 2.0 release introduces breaking API changes, and comes with a full prescriptive migration guide that links to per-area documentation covering telemetry, packages, source generation, types, encoders, node states, identity, certificates, configuration, sessions / subscriptions, alarms / model change, and TimeProvider.
Most of the mechanical migration work is automated:
OPCFoundation.NetStandard.Opc.Ua.MigrationAnalyzerNuGet — install it in your project to get analyzer warnings (UA0001–UA0022)- one-click code fixes for the patterns in the guide. Setup steps are in the package's NugetREADME.md.
- Migration agent skill — the
opcua-v20-migrationskill walks Copilot / Claude / any coding agent through installing the NuGet, runningdotnet format analyzersto apply auto-fixes, and handling the small residual manual patterns. The skill knows which sub-doc to load for each symptom so it stays context-efficient.
If you are still on 1.x and not ready to upgrade, stay on the
master378
branch — it continues to receive security and critical-bug fixes.
🤝 Contributing and license
Community contributions are welcome. Fork the repository, make your changes on a branch, and open a pull request; see CONTRIBUTING.md for the contribution workflow.
Contributors must sign the OPC Foundation Contributor License Agreement (CLA). The CLA "I AGREE" gate is presented automatically on your first PR.
The project is licensed under the OPC Foundation MIT License. Report security vulnerabilities via the process documented in SECURITY.md.
📚 Further reading
- Documentation index — every per-feature doc with a one-line description.
- What's New in 2.0 — narrative tour of the 1.5.378 → 2.0 changes grouped by theme and layer.
- OPC UA Profiles and Facets — facets / transports / security policies the stack implements.
- Migration Guide — prescriptive
per-version migration reference (links to
docs/migrate/2.0.x/). - OPC UA Online Reference — the official OPC 10000 series specification index.
- OPC UA .NET Samples — companion repository with more sample applications.
- Preview NuGet feed — prerelease builds from Azure DevOps.