Klaus LandsdorfandMarc Schier
2a619cdf05
# Description Two client fixes, one commit each. **1. `CoreClientUtils.SelectEndpoint` skips OpenAPI endpoints.** - An HTTPS listener with the REST binding announces its OpenAPI endpoint with the same URL and message mode as its binary mode-None endpoint. `SelectEndpoint` matched on the URL scheme and the message mode only, so the first of the two in the GetEndpoints result won, in the main pass and in the HTTPS fallback for `useSecurity`. - The OpenAPI mapping (OPC 10000-6 §G.3) is the REST binding, not the binary transport the caller connects with. With the default channel bindings no channel factory is registered for the OpenAPI profile (`ClientChannelManager` maps it to `opc.https+webapi`), so a Session cannot be created on it; with the REST channel registered, the Session silently runs over REST. - Following OPC 10000-4 §5.5.4 (select by `TransportProfileUri`), both passes now skip endpoints with the HTTPS or WSS OpenAPI transport profile. Endpoints without a `TransportProfileUri` are selected as before. **2. A closed Session does not send requests without authenticationToken.** - A request with a null `authenticationToken` is a session-less invocation (OPC 10000-4 §6.3.1). - After `CloseAsync(closeChannel: false)`, a request sent through the same `Session` object went out that way. A server that supports session-less invocation processed it as one instead of rejecting it. - `Session` now records that a session was created (`SessionCreated` with a non-null cookie; `OpenAsync` now calls it through the override instead of `base.SessionCreated`). From then on `UpdateRequestHeader` fails a request without token locally with `Bad_SessionIdInvalid`, and the request is never sent. CreateSession and ActivateSession are exempt, so reopening and reactivating keep working. A Session that was never created behaves as before. ## Changes - `src/Opc.Ua.Client/CoreClientUtils.cs`: `IsOpenApiEndpoint`, used in both selection passes; the `<returns>` documentation says that an OpenAPI endpoint is never returned. - `src/Opc.Ua.Client/Session/Session.cs`: overrides of `SessionCreated` and `UpdateRequestHeader` (both virtual in `SessionClient` / `ClientBase`), one `volatile bool` field. ## Tests - **New, part 1** (`Opc.Ua.Client.Tests`, `CoreClientUtilsSelectEndpointTests`): `SelectEndpointSkipsTheOpenApiEndpointListedFirst`, `SelectEndpointWithSecurityFallbackSkipsTheOpenApiEndpoint`, `SelectEndpointSkipsTheWssOpenApiEndpoint`, `SelectEndpointReturnsNullWhenOnlyOpenApiEndpointsMatch` (with and without `useSecurity`), `SelectEndpointKeepsTheFirstBinaryEndpointWithoutTransportProfile`. - **New, part 2** (`Opc.Ua.Client.Tests`, `SessionTests` with the channel mock): `RequestAfterCloseFailsLocallyWithBadSessionIdInvalidAsync` (the Read never reaches the channel), `ActivateSessionIsStillSentAfterCloseAsync`, `RequestAfterANewSessionIsCreatedCarriesItsTokenAsync`, `RequestBeforeASessionIsCreatedIsNotRefusedAsync`. - **Updated:** `Opc.Ua.Sessions.Tests` `ClientTest.ReconnectSessionOnAlternateChannelAsync` closes the Session and then the channel. The read that follows now fails with `Bad_SessionIdInvalid` before it reaches the closed channel, and the test expects that code instead of the codes of the closed channel (on master it gets `Bad_NotConnected`). - **Fail without the fix:** with `CoreClientUtils.cs` and `Session.cs` from master, all five SelectEndpoint tests that involve an OpenAPI endpoint (6 cases) fail, as does `RequestAfterCloseFailsLocallyWithBadSessionIdInvalidAsync`, and `ReconnectSessionOnAlternateChannelAsync` fails with `Bad_NotConnected`. `SelectEndpointKeepsTheFirstBinaryEndpointWithoutTransportProfile` and the three other Session tests pass there by design: they pin behaviour that must not change. - `Opc.Ua.Client.Tests` 2743/2743 and `Opc.Ua.Sessions.Tests` 672 passed / 287 skipped / 0 failed on net10.0 and net8.0 (macOS). - `Opc.Ua.Client` builds for net48, net8.0, net9.0 and net10.0 with 0 warnings; `dotnet format` (whitespace, style, analyzers) reports nothing on the changed lines; changed lines covered 26/26 (100 %) with the two suites above. - Fork CI (full matrix incl. macOS) and CodeQL: [CI run 37128535726](https://github.com/biancode/UA-.NETStandard/actions/runs/37128535726) (154 jobs) and [CodeQL run 37128537502](https://github.com/biancode/UA-.NETStandard/actions/runs/37128537502). CodeQL is green; CI is green except `Opc.Ua.Interop.Tests` `LegacyClientExtendedCheckAsync("ComplexTypes")` / `LoadAndDecodeLegacyComplexTypesAsync` ("1 of N structures were not decoded"), which came with #4630 and fails the same way on other open pull requests; this change does not touch ComplexTypes. ## Notes for review - Part 2 changes the code a caller sees for a request on a closed Session: `Bad_SessionIdInvalid` is raised locally instead of whatever the server or the closed channel answers. Reconnect paths are not affected, because they use ActivateSession or a new Session object. If you prefer to keep part 2 out, its commit can be dropped without affecting part 1. - The test framework's own endpoint selection (`ClientFixture`) is left as it is; the upstream test servers do not need the change. ## Related Issues - Fixes #4645 ## Checklist - [x] I have signed the [CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf) and read the [CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md) doc. - [x] I have added tests that prove my fix is effective or that my feature works and increased code coverage. - [x] I have added all necessary documentation. - [x] I have verified that my changes do not introduce (new) build or analyzer warnings. - [ ] I ran **all** tests locally using the **UA.slnx** solution against at least .net **framework** and .net **10**, and all passed. (Affected suites on net10.0 and net8.0 locally on macOS; .NET Framework is covered by the fork CI's Windows net48 legs.) - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received. --------- Co-authored-by: Marc Schier <marcschier@users.noreply.github.com>
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; 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 30270 / OPC UA for Asset Administration Shell V2 and V3, OPC 10100-1 (WoT Connectivity), Part 200 (Industrial Automation), OPC 40001-1/-2/-3/-4/-101 (Machinery with Process Values, Job Management, Energy and Result Transfer), OPC 34100 (Energy Consumption Management), OPC 30081 (PA-DIM), OPC 40010-1 (Robotics), OPC 40223 (Pumps and Vacuum Pumps), OPC 40200 (Weighing Technology) with OPC 30050 (PackML).
- 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
To run a first OPC UA client and server, from NuGet packages or from the samples in this repository, follow Getting started. The documentation index then leads from the core concepts to advanced and experimental features.
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 reference individual packages directly, e.g.
OPCFoundation.NetStandard.Opc.Ua.Client for clients or
OPCFoundation.NetStandard.Opc.Ua.Server for servers. Preview builds from
every successful master build are available from the
GitHub Packages NuGet feed,
which is the only feed they are published to. nuget.org receives a version
only through a manually approved promotion from a release/<major>.<minor>
branch — that is where the 2.0.0-preview.N packages already on nuget.org
came from, via the earlier release/2.0.0 line. To use those, enable
prerelease packages and float with 2.0.0-preview.* until 2.0.0 is
released. The XRegistry, WoT Connectivity, Vision, Robotics,
Redundancy, Positioning, OpenUSD, ISA95, AI, and DI package families remain
preview packages when the root version is promoted to a stable version, and
keep their own -preview.N versions on nuget.org. See
docs/ReleaseProcess.md for how and when stable
versions are released.
Samples
The stack also includes a large collection of platform-independent sample applications that turn its core services and companion models into runnable client/server workflows. More applications, including platform-specific examples, are available 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 for the migration sub-topics.
Most of the mechanical migration work is automated:
OPCFoundation.NetStandard.Opc.Ua.MigrationAnalyzerNuGet — install it in your project to get 26 analyzer rules throughUA0030(excludingUA0013,UA0016,UA0017, and the shim-onlyUA0029) plus 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.
Copilot CLI discovers the skill automatically inside a clone. To install it for use in any repository:
copilot plugin marketplace add OPCFoundation/UA-.NETStandard
copilot plugin install opcua-v20-migration@opcua-dotnet
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.
- Preview Nuget package feed —
prerelease builds from every successful
masterbuild.