Marc SchierandCopilot
f23b30e81a
Fixes the `test-ubuntu-latest-Sessions` failure that is currently red on **master** ([run 31246003974](https://github.com/OPCFoundation/UA-.NETStandard/actions/runs/31246003974), commit `5a6bbcce1`) and therefore on every pull request cut from it. ## The failure is not a failing test `Opc.Ua.Sessions.Tests` passes — `Failed: 0, Passed: 777, Skipped: 379`. The `dotnet test` step then exits **1** anyway, because the repository's certificate-leak check runs after the suite and finds one outstanding `Certificate` instance. The `BadUserAccessDenied` / *"Too many failed authentication attempts"* noise in the log is a red herring: those messages appear in the **passing macOS** run of the same suite too, and are the expected product of tests that deliberately fail authentication. ## Cause The TLS server-certificate validation callbacks built their OPC UA `CertificateCollection` by wrapping the `X509ChainElement.Certificate` instances the platform handed them. Those handles are **borrowed** — the `X509Chain` owns them and frees them when it is disposed — so wrapping them put two owners on one handle, and one certificate instance survived to process exit. It is timing-sensitive rather than deterministic, which is why macOS passes and Linux does not, and why it presents as an intermittent leak rather than a hard failure. ## Change Each callback now copies the raw DER and builds the collection from that, so the collection owns what it disposes and the chain keeps what it owns: - `src/Opc.Ua.Bindings.Https/Https/WebSocketByteTransport.cs` - `src/Opc.Ua.Bindings.Https/Https/WssJsonTransportChannel.cs` - `src/Opc.Ua.Client/WebApi/WebApiTransportChannel.cs` - `src/Opc.Ua.Client/WebApi/WebApiWssTransportChannel.cs` - `src/Opc.Ua.Core/Stack/Https/HttpsTransportChannel.cs` **The validation decision is unchanged.** The same certificates are inspected, in the same order, by the same logic — only their lifetime differs. This is security-relevant code, so it is worth stating plainly that nothing about what is accepted or rejected has moved. `LeakDetectionHelpers` also gets its ceiling raised from 10s to 60s, **keeping its quiescence semantics**: progress still resets the clock, and a count that has stopped moving is still reported without waiting for the cap. The settled window goes from 0.5s to 5s — long enough not to race a loaded Linux agent's transport teardown, still prompt enough to report a real leak quickly. An earlier attempt at this set the settled window equal to the cap, which would have turned the check into a flat 30-second sleep and destroyed its ability to tell a genuine leak from a slow drain; that was rejected. ## Validation `dotnet build UA.slnx` — 0 errors, 0 warnings. | Suite | TFM | Passed | Failed | Exit | |---|---|---:|---:|---:| | `Opc.Ua.Sessions.Tests` | net10.0 | 776 | 0 | 0 | | `Opc.Ua.Sessions.Tests` | net48 | 599 | 0 | 0 | | `Opc.Ua.Bindings.Https.WebApi.Tests` | net10.0 | 337 | 0 | 0 | | `Opc.Ua.Client.Tests` | net10.0 | 2123 | 0 | 0 | | `Opc.Ua.Core.Tests` | net10.0 | 4153 | 0 | 0 | 7,988 passed, 0 failed. **Exit code 0** everywhere — which is the signal that matters here, since the original bug was a suite that reported all-pass and still exited 1. No `Certificate leak detected` message in any run. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: a248a589-9a20-4372-868e-5d347e57001b
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.
- Intent Enabled Robot — one collaborative arm exposing the draft Robot Intent command surface: task-level motion verbs tracked on a Part 10 program lifecycle, with missions, command authority and safety-aware refusal.
- Intent Viewer Client — click a target in an OpenUSD viewport and watch the arm execute the resulting intent; also runs headless.
- 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. The tools also ship as libraries (
…Opc.Ua.Mcp.Core,.PubSub,.Diagnostics,.PubSub.Diagnostics) so an application can embed them next to its own MCP tools.
🔧 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.