# Description Correct ownership, endpoint validation, policy propagation, subscription delivery, file handling and generated-model behavior across the stack, tools and samples. Add focused regression tests and update the corresponding guides and sample documentation. ### Previously included corrections - Require an active, matching session to generate or access transient ResultTransfer file handles. Cover both sessionless generation and reads against a handle owned by an active session, using live session owners in the Machinery tests. - Keep physical filesystem operations within their configured mount and apply the same confinement checks throughout file operations. - Validate LDS semaphore paths consistently during server registration and registration-store maintenance. ### Individual issues addressed | # | Component | Issue and correction | |---|---|---| | 1 | AI jobs and transfers | Jobs and transfers did not consistently retain their creator's identity and session. Apply ownership checks to descendants, file handles, subscriptions and execution, and recheck deployment permissions before dispatch. | | 2 | Password-management client | Password-bearing calls could use signing-only channels or follow a replacement connection. Capture an encrypted transport generation and keep dispatch bound to it; preserve ordinary non-password edits. | | 3 | GDS and certificate-push clients | Connections omitted hostname verification. Validate the original configured DNS name or IP address before session activation. | | 4 | Certificate push | Private-key uploads could use signing-only calls. Require an encrypted, generation-bound dispatch while preserving certificate-only updates and restoring the caller's identity afterward. | | 5 | MQTT client | The .NET Framework custom-trust callback could discard TLS hostname, certificate-availability and usage errors. Retain those checks while supporting configured issuer trust. | | 6 | DTLS handshake | Certificate trust was not tied to the configured peer address. Match the certificate's DNS or IP identity to the intended endpoint. | | 7 | Replicated address spaces | Serialized nodes lost per-node and descendant permission metadata. Preserve role permissions, user-role permissions and access restrictions, including updates to existing replica nodes. | | 8 | MCP PubSub imports | Imports without groups skipped checks on the effective broker destination. Check the actual endpoint before resolving credentials or activating the connection. | | 9 | Reference-server accounts | A disabled username account could authenticate again with its previous roles. Reject disabled accounts during fresh authentication. | | 10 | Console reference client | The sample disabled hostname checks when connecting to an otherwise trusted peer. Retain the original requested host and validate it before activation. | | 11 | Capture replay and export | Replay and raw export could accept non-capture files or include key material. Require complete PCAP/PCAPNG containers and exclude key sidecars and decryption-secret blocks. | | 12 | PubSub adapter fallback | The fallback client configuration automatically accepted peer certificates. Apply normal trust and hostname validation before activation or reads. | | 13 | Kafka transport | Explicit TLS enablement was checked but did not reach both final Confluent configurations. Use the same effective protocol for validation, producers and consumers. | | 14 | PubSub actions | Configuration rebuilds could widen a connection-local action handler's scope. Preserve its original connection association and reject mismatched dispatch. | | 15 | PubSub readers | Reader-level message-protection settings were accepted but ignored. Apply the effective group and reader settings before accepting and publishing received values. | | 16 | PubSub key groups | Different `SecurityGroupId` values could share one connection-wide key context. Reject mixed groups on a connection and require separate connections for distinct groups. | | 17 | MCP session registrations | Session-name replacement or reuse could retain another registration's credential bindings. Bind access to the registration, caller and authenticated endpoint, and preserve that identity when borrowing sessions. | | 18 | Viewer HTTP host | Requests reached the viewer's OPC UA session without consistent Host, Origin and port checks. Validate the request destination and browser origin before using the session, while retaining supported local MCP clients. | | 19 | Vision file operations | File operations did not consistently apply protected-file checks, and remote handles lacked caller and connection context. Apply the shared checks and use host-side opaque handles bound to caller, target and generation. | | 20 | DTLS record integrity | The integrity-only MAC used a truncated sequence number. Authenticate the full reconstructed sequence number and epoch so records remain distinct across rollover. | | 21 | AMB client sample | Connection setup omitted hostname validation. Preserve the originally requested host and verify the peer identity before activation. | | 22 | Robot sample writes | The R2 `SpeedOverride` callback could target R1 state. Bind each callback to its own robot and apply that robot's write policy. | | 23 | AI result properties | Optional result children inherited remotely writable defaults. Preserve their declaration restrictions and keep server-produced results read-only. | | 24 | WSS peer-trust updates | Existing channels did not consistently respond to peer-trust changes. Revalidate complete chains for forward and reverse WSS channels and close only those that no longer validate. | | 25 | GDS revocation checks | Caller-provided certificates could cause issuer retrieval from embedded URLs. Resolve validation from configured local trust, issuers and CRLs without fetching caller-provided locations. | | 26 | GMS observations | Published correction observations retained writable model defaults. Reject remote writes while preserving publisher-side updates. | | 27 | Production-dataset monitoring | Subscription admission and delivery could use the reporter's context instead of each subscriber's permissions. Evaluate the subscriber at admission and on every delivery, including cancellation and disposal paths. | | 28 | WoT MQTT destinations | Hostless MQTT forms could imply a localhost destination before loopback checks. Reject them before credential lookup or connection attempts and validate the effective endpoint. | | 29 | XRegistry opaque reads | Content-ID reads and notifications did not consistently honor encrypted-read requirements or the currently accepted transport. Recheck the bound endpoint and reject transport downgrades before rebinding, including when protected values are already queued. | | 30 | PubSub capture dissection | Key loading did not consistently check the configured capture-root boundary. Check each actual key path immediately before opening it. | | 31 | PubSub publication queues | Imported WriterGroup queues were not fully checked against publish-topic grants. Check the destination actually used by each group. | | 32 | MCP PubSub mutations | A caller-supplied mode could select subscribe grants for an operation that publishes. Derive the required direction and parent context from the actual mutation. | | 33 | Generated write masks | Model import and generation could widen an explicit `UserWriteMask`. Preserve it through import, copy, merge, inheritance and dependency metadata. | | 34 | Generated method flags | An explicit `UserExecutable=false` could be lost. Preserve its specified state and resulting method behavior through the same model paths. | | 35 | Generated role identifiers | Unresolved role identifiers could cause permission entries to be omitted. Preserve namespace-qualified role IDs and report a diagnostic when a policy cannot be represented. | | 36 | Aggregation-server defaults | The `localhost` default did not reliably constrain listener binding. Use numeric loopback for the default endpoint and command-line fallback. | | 37 | Certificate-validation cache | Cached results could skip current leaf or issuer validity checks. Recheck validity windows on cache hits and keep hostname validation independent of cached chain trust. | | 38 | Software-update folders | Revision names and marker contents containing dot segments could select paths outside the software root. Normalize and check every derived path against that root. | | 39 | USDA arrays | Array elements were not encoded for their string or asset context. Escape them as data and preserve valid composition and round-trip behavior. | | 40 | Adapter hot reload | A changed dataset definition with the same name could keep old fields, subscriptions or cached values active. Compare complete immutable definitions and retire old state before replacement. | | 41 | Adapter index ranges | Subscription publication could ignore `IndexRange` and return the complete value. Preserve the requested projection and its status and timestamps; reject unsupported range providers. | | 42 | PubSub metadata and targets | Metadata from one connection could change another connection's target mapping. Scope metadata to its connection and provenance, and resolve targets using actual typed field IDs rather than field names or unintended positional fallback. | | 43 | Scales product locks | Product locks were not applied across every remote mutation path. Apply them consistently to value writes, filling calculations and related recipe/controller operations while retaining permitted updates. | | 44 | Event permission caching | Cached event decisions could outlive identity, role or node-policy changes. Revalidate the current subscriber, event type and source permissions instead of reusing a stale decision. | | 45 | WoT Modbus destinations | Hostless Modbus forms could imply localhost before loopback checks. Reject them before connecting and validate the effective endpoint. | | 46 | MCP local PKI tools | Peer-trust mutations did not consistently require the caller's `CertificateAdministration` grant. Check the capability before trust and untrust operations. | | 47 | Robot-control HTTP bridge | The bridge lacked consistent Host, Origin and port validation and caller-specific session grants. Apply those checks before borrowing the OPC UA session and retain supported local clients. | | 48 | Subscription transfers | Transferred subscriptions could retain cached notifications after the destination's permissions changed. Require authorization continuity between source and destination identities and roles, invalidate stale retransmission data when continuity fails, and preserve retransmission behavior for compatible transfers. | ### Compatibility notes - Replication uses the versioned NSRP v1 policy envelope. Upgrade peers together and re-encode or reseed legacy topology from the authoritative model; missing permission metadata is not inferred from old records. - Integrity-only DTLS peers must be upgraded together for the full sequence/epoch MAC. AEAD behavior is unchanged. - Distinct PubSub key groups require separate connections. - Custom sessions that cannot capture the actual encrypted transport, and subscription providers that cannot honor a requested range, are rejected rather than silently changing the requested behavior. - Subscription transfers retain retransmission data only when the destination authorization remains compatible with the source snapshot; otherwise the old sequence numbers and cached data are invalidated. ## Related Issues No separate tracking issue is linked. The individual corrections are listed above. ## Checklist _Put an `x` in the boxes that apply. You can complete these step by step after opening the PR._ - [ ] 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. - [ ] 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. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received.
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 10 (Programs), 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), Part 110 (Asset Management Basics), 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 40100-1/-2 (Machine Vision control and asset management), OPC 40501-1 and OPC 40505 (Machine Tools and independent wireless peripherals), OPC 40210 (Geometric Measurement Systems, with its documented upstream Production-facet exception), OPC 40020-1 (Cranes and Hoists), OPC 40223 (Pumps and Vacuum Pumps), OPC 30010 (AutoID Devices), OPC 40200 (Weighing Technology) with OPC 30050 (PackML).
- Hosting and code generation —
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.
The recycling operator console demonstrates live browser monitoring, native companion-specification inspection, material genealogy, and authorized controls over the synthetic recycling line.
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, Robotics, CranesHoists,
Redundancy, Positioning, OpenUSD, and AI package families, the Vision.OpenUsd
renderer, and the Robotics MCP extension remain
preview packages when the root version is promoted to a stable version, and
keep their own -preview.N versions on nuget.org. This includes all CranesHoists
model/server/client/MCP packages and their Debug variants.
The Vision, MachineVision, MachineTool (including WMTP), and GMS
model/client/server packages and their MCP packages follow the root version
without a preview-only override;
development builds still inherit the root prerelease version. See
docs/ReleaseProcess.md for how and when stable
versions are released.
Samples
The platform-independent sample applications show how to use the stack's core services and companion models in 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 exposing OPC UA client operations to LLMs and Copilot. Embeddable libraries provide Part 4 services, PubSub, diagnostics, Robotics and Vision, plus industrial companion profiles for AMB, Machinery, Scales, Pumps, AutoID, Device Integration, ISA-95 and Positioning. The WoT and xRegistry profiles add asset/registry management and bounded document validation, planning and NodeSet conversion. Stack workflow profiles provide GDS/credential issuance, roles/users, files, alarms, history, schemas, and host-authorized PubSub and live WoT execution.
🔧 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 remaining manual changes. It selects the migration sub-document for each symptom.
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.