# Description Nullable reference types are now enabled once, in `common.props`, and every project in the repository builds warning-clean with them. **Configuration** - `<Nullable>enable</Nullable>` lives in `common.props`. All per-project `<Nullable>` settings are removed: 178 project files (enable, annotations, and the `disable` in the three Aot test projects). - 419 per-file `#nullable enable`/`restore` directives and the 4 `#nullable disable` directives are removed. - Kept on purpose: - The 5 `<auto-generated>` schema files (`UANodeSet.cs`, `UA Type Dictionary.cs`, `OPCBinarySchema.cs`, `SecuredApplication.cs`, `PInvokeHelper.cs`) keep `#nullable enable`. The compiler ignores the project setting in generated code, so the directive is required there. - `tests/Opc.Ua.Interop.LegacyPeer` keeps `disable`. It builds against the 1.5.378 packages and does not import the repository props. - `docs/DeveloperGuide.md` and `.github/copilot-instructions.md` now describe the central setting. **Migration** (the 43 unset and 13 annotations-only projects, roughly 10k diagnostics) - **Production code: annotated at the declarations.** Covers `tools/Opc.Ua.SourceGeneration.Core`, `src/Opc.Ua.Lds.Server` and the LDS sample. - Members, parameters and returns are nullable where null actually flows. - Null-check helpers carry `[NotNullWhen]` (`IsNull`, `IsValidXmlName`, `IsMethodTypeDesign`). - `CoreUtils.Format`, `Utils.Format`, `ITemplateWriter.WriteLine` take `params object?[]`. `Template.AddReplacement` takes `string?` (rendering already skips null replacements). - `IRegisteredServerStore.RegisterAsync` returns `Task<RegistrationEntry?>`: it returns null when a registration is removed. - Dereferences backed by an invariant (for example, the validated model) use `!`, so runtime behaviour is unchanged. - **Behavioural changes in production code** (small, deliberate): - `NodeSetToModelDesign` throws `InvalidOperationException` when the file is not a NodeSet. Before, it threw a NullReferenceException on the next line. - `ModelDesignValidator` starts its lookup tables empty instead of null. A redundant `if (m_nodes == null) return;` guard is gone. - **Test code: minimal annotations.** - `?` on values that can be null, `!` where the test asserts non-null. - `= null!` for fixture members assigned in SetUp. - `TryGetStructure<T>(out T? x)` where the inferred `T?` broke the `IEncodeable` constraint. - A few redundant `== null` checks on structs (`NodeId`, `ArrayOf<T>`) folded into the adjacent `IsNull`/`Count` checks. **Notes for reviewers** - The diff is large (~1,500 files) but almost entirely mechanical: `?`, `!` and directive removal. The non-annotation changes are listed above. - Known follow-up, not done here: `IModelDesign.Namespaces/TargetNamespace/NamespaceUris` stay non-nullable even though the validator returns null before it loads a dictionary. Making them nullable would ripple through every generator call site. ## Related Issues - Fixes #4439 ## Checklist - [ ] 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. - [ ] 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. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received. The "no new warnings" box covers net10.0 and net48: full non-incremental builds of `UA.slnx`, `tools/SourceGeneration.slnx`, `tools/MigrationAnalyzer.slnx` and the Aot test projects finished with 0 warnings and 0 errors under the repository's warnings-as-errors settings. net9.0 and net8.0 also had no nullable diagnostics, but they were not rebuilt after the final fixes. Tests have not been run locally yet. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
OPC 10000-21 Onboarding Demo
This sample demonstrates the registrar-administration part of OPC 10000-21 end to end over a real OPC UA connection. It uses only the model and runtime APIs shipped by this repository:
OnboardingRegistrarloads the generatedOpc.Ua.Onboardingmodel, exposes the standardDeviceRegistrar_Administrationobject, and bindsRegisterTickets/UnregisterTicketsto an injectedMemoryTicketStore.OnboardingClientconnects with a managed session, resolves the well-known registrar NodeId, and uses the DI-providedOpc.Ua.Gds.Client.OnboardingClient.run-onboarding-demo.ps1builds both applications, waits until the OPC UA server reaches its running state, proves an anonymous caller is denied, runs the authenticated client, and stops the exact registrar process in afinallyblock.
The demo covers ticket administration. It does not implement the
device-facing ProvideIdentities flow or a complete production GDS.
Run the complete demo
From the repository root:
pwsh samples/Gds/run-onboarding-demo.ps1
The script uses
opc.tcp://localhost:62560/OnboardingRegistrar by default. Select a
different port with:
pwsh samples/Gds/run-onboarding-demo.ps1 -Port 62660
Successful output ends with:
REGISTER Good Good
UNREGISTER Good
UNREGISTER_AGAIN BadNotFound
ONBOARDING_DEMO_OK
Pass -Keep to retain the temporary PKI stores and registrar logs for
diagnostics.
Run the applications manually
Start the registrar:
dotnet run --project samples/Gds/OnboardingRegistrar -f net10.0 -- `
--port 62560 `
--pkiRoot "$env:TEMP\opcua-onboarding-registrar"
After ONBOARDING_REGISTRAR_READY is printed, run the client:
dotnet run --project samples/Gds/OnboardingClient -f net10.0 -- `
--endpoint "opc.tcp://localhost:62560/OnboardingRegistrar" `
--pkiRoot "$env:TEMP\opcua-onboarding-client"
Wire contract
The client API uses the Part 21 types directly:
ArrayOf<StatusCode> results = await onboarding.RegisterTicketsAsync(
[
new ByteString(firstTicket),
new ByteString(secondTicket)
]);
EncodedTicket is a subtype of ByteString. The server returns one
StatusCode for every supplied ticket.
Security
The demo selects SignAndEncrypt with Basic256Sha256. For a
self-contained local run, both applications automatically accept the
other application's newly created certificate and store it under an
isolated temporary PKI root. The script also generates a one-run random
username and password, grants that user the generated RegistrarAdmin
role, and restricts the two ticket methods to that role. The endpoint
also permits an anonymous bootstrap session because ManagedSession
activates its configured identity provider after creating the session;
anonymous users have no permission to call the registrar methods.
Automatic certificate acceptance is a sample-only convenience. A production registrar must use managed trust lists, authenticate and authorize registrar administrators, persist tickets in a protected store, and apply the audit/redaction requirements described in the GDS developer guide.
For a manual run, set ONBOARDING_DEMO_USER and
ONBOARDING_DEMO_PASSWORD to the same non-empty values in both
terminals before starting either application. Do not reuse demo
credentials in a production deployment.