# Description
Adopt
[`System.TimeProvider`](https://learn.microsoft.com/dotnet/api/system.timeprovider)
across the stack so that every place that creates timers, runs duration
math, or schedules periodic work is mockable, deterministic in tests,
and immune to wall-clock changes.
The migration touches Core, Core.Types, Server, Client, PubSub,
Configuration, Gds (server + client), Lds, and the Quickstarts/Console
reference apps. Per-component changes follow the same pattern:
1. Add a `private readonly TimeProvider m_timeProvider;` field.
2. Accept a nullable `TimeProvider? timeProvider = null` as the **last**
constructor parameter (new overload; legacy constructor stays for binary
compatibility and delegates with `timeProvider: null`).
3. Initialise the field with `m_timeProvider = timeProvider ??=
TimeProvider.System;`.
4. Replace `new Timer(...)`, `Stopwatch`, `HiResClock.*`,
`DateTime.UtcNow`-based duration math, and `Task.Delay(delay, ct)` in
timing loops with the matching `m_timeProvider` API (`CreateTimer`,
`GetTimestamp` / `GetElapsedTime`, `GetUtcNow().UtcDateTime`,
`Task.Delay(delay, m_timeProvider, ct)`).
5. Wire the provider through DI: `AddOpcUaServerBuilder` /
`AddOpcUaClientBuilder` register `TimeProvider.System` via
`TryAddSingleton<TimeProvider>()` so tests can swap in
`Microsoft.Extensions.Time.Testing.FakeTimeProvider`.
`HiResClock` itself is kept (so the
`ApplicationConfiguration.DisableHiResClock` schema flag still
round-trips), but **every public member** is now `[Obsolete]` with a
single shared message pointing to the new migration-guide section. The
few internal call sites that still need to set/read `HiResClock` are
wrapped with `#pragma warning disable CS0618`.
### Highlights per component
- **Core / Stack** — `Opc.Ua.Core`, `Opc.Ua.Core.Types`, channel
pipeline (`UaSCBinaryClientChannel`, `ChannelToken`,
`UaSCBinaryChannel`), `ApplicationConfiguration`, certificate
validators, `JwksIssuerKeyResolver`, `TimeProviderExtensions` polyfills
(`GetTimestampMilliseconds`, `GetTickCount`,
`CancellationTokenSource(timeout, timeProvider)`, `Task.Delay(delay,
provider, ct)` polyfill for older TFMs).
- **Server** — session lockout, subscription pipeline
(publish/sample/keep-alive/lifetime), `MonitoredItemQueue`, alarm
sampling rate, `IntervalRunner`, server diagnostics, configuration state
machines, hosted services.
- **Client** — `Session`, managed/V2 subscription engines, reconnect
handlers, channel keep-alive, periodic publishing, complex-type
discovery polling.
- **PubSub** — `IntervalRunner` pipeline, message-receive timers,
MQTT/UDP keep-alive, publishers/readers.
- **Gds / Lds** — `LdsServer`, `LinqApplicationsDatabase` expiry
housekeeping, GDS clients (push, pull), `DirectoryCertificateStore`,
`ConnectionStateMachine`, classic subscription engine.
- **Quickstarts / Console samples** — `SampleNodeManager`,
`ReferenceNodeManager`, `AlarmNodeManager`, `BoilerState`,
`MemoryBufferState`, `PublishedValuesWrites`. Samples resolve via
`(Server as ITimeProviderProvider)?.TimeProvider ?? TimeProvider.System`
so existing ctor signatures stay binary-compatible.
- **Tests** — `Opc.Ua.PubSub.Tests` adds `IntervalRunnerTests`; existing
`SubscriptionTests`, `UaPublisherTests`, and `TestDataSystem` move off
`HiResClock`. Added `Microsoft.Extensions.TimeProvider.Testing` package
for `FakeTimeProvider` (project-load warning surfaces on net48/net472
only — runtime is .NET 8+).
### Migration guide
New section [**Time and Timer abstraction
(`TimeProvider`)**](Docs/MigrationGuide.md#time-and-timer-abstraction-timeprovider)
documents:
- The canonical replacement table (`HiResClock.UtcNow` →
`timeProvider.GetUtcNow().UtcDateTime`, `HiResClock.TickCount64` →
`timeProvider.GetTimestamp()`, `new Timer` → `timeProvider.CreateTimer`,
`Task.Delay(delay, ct)` → `Task.Delay(delay, timeProvider, ct)`, …).
- The `TimeProvider? timeProvider = null` + `??=` constructor pattern.
- DI wiring and how to swap in `FakeTimeProvider` in tests.
- Before/after snippets for `HiResClock.TickCount64`,
`HiResClock.UtcNow`, and `new Timer(...)`.
## Related Issues
- Fixes#2458
## 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.
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.
## Proposed changes
Implements **OPC UA Part 11 (Historical Access)** end-to-end via a clean
**provider model** that lets servers back historizing variables with any
time-series storage engine. A reference-quality **in-memory engine**
ships in `Opc.Ua.Server` so getting started requires no extra packages.
The implementation replaces the legacy `HistoryArchive` /
`HistoryDataReader` / `HistoryFile` / `IHistoryDataSource` files
(removed from `Quickstarts.Servers/TestData/`) with a stack-level Part
11 surface.
### What's new
- **Server provider model** in `Libraries/Opc.Ua.Server/Historian/`:
- Umbrella `IHistorianProvider` + narrow capability interfaces
(`IHistorianDataProvider`, `IHistorianModifiedProvider`,
`IHistorianAtTimeProvider`, `IHistorianProcessedProvider`,
`IHistorianAnnotationProvider`, `IHistorianEventProvider`,
`IHistorianTransactionalProvider`).
- `HistorianDispatcher` — routes HistoryRead / HistoryUpdate (raw,
modified, at-time, processed, events, annotations) including
event-`WhereClause` evaluation via the framework's `FilterEvaluator`,
audit-event reporting, and continuation-point lifecycle.
- `HistorianProviderRegistry` with Node → Namespace → Default
precedence; surfaced via `IHistorianRegistryProvider` on
`ServerInternalData`.
- Fluent `HistorianBuilder`
(`server.UseHistorian().UseInMemory().Historize(...).RegisterAsDefault()`).
- Lazy `HistoricalDataConfigurationType` companion installer
(`OnPopulateBrowser`-attached).
- `ServerSystemContext` now exposes `IServerInternal Server { get; }` so
infrastructure code stops relying on the per-NM `SystemHandle`.
- **In-memory reference engine** (`InMemoryHistorianProvider`) — raw,
modified, processed via framework fallback, at-time via framework
fallback, annotations, events, transactional batches.
- **Client surface** in `Libraries/Opc.Ua.Client/Historian/`:
- `HistoryClient` with `IAsyncEnumerable<DataValue>`
raw/modified/at-time/processed/annotation reads (transparent
continuation-point handling and `try/finally`-based release on iterator
abandonment).
- `session.Historian()` extension.
- Capability discovery (`GetServerCapabilitiesAsync`,
`GetConfigurationAsync`).
- **Node-manager wiring** through both `AsyncCustomNodeManager` and
`CustomNodeManager2` (sync-via-dispatcher).
- **Capability rollup** — `DiagnosticsNodeManager` populates the
server-wide `HistoryServerCapabilities` as the union of registered
providers' `GetCapabilitiesAsync(NodeId.Null, ...)` (runs whether the
node was loaded from the predefined nodeset or freshly created; fully
async).
- **Audit-event reporting** for HistoryUpdate (gated on
at-least-one-success):
`AuditHistoryValueUpdateEventType`,
`AuditHistoryAnnotationUpdateEventType`,
`AuditHistoryRawModifyDeleteEventType`,
`AuditHistoryAtTimeDeleteEventType`, `AuditHistoryEventUpdateEventType`,
`AuditHistoryEventDeleteEventType`.
- **ReferenceServer + TestData** historize sample variables through the
new pipeline (replaces the deleted legacy `HistoryArchive`).
- **Comprehensive developer documentation** in
`Docs/HistoricalAccess.md` (~657 lines): server-developer guide,
provider-author guide, client-developer guide, capability discovery,
auditing, limitations/roadmap.
### Tests
| Suite | Files | Tests |
| --- | --- | --- |
| Server unit (Opc.Ua.Server.Tests/Historian) | dispatcher,
event-dispatcher, registry, in-memory provider, transactional provider,
concurrency, coverage, event-filter target | **34** passing |
| Client integration (Opc.Ua.Client.Tests/Historian) |
`HistoryClientIntegrationTests` over the live `ReferenceServer` via
`ServerFixture` | **4** passing |
| AOT (Opc.Ua.Aot.Tests/HistoryAotTests) | positive assertions against
historized `Scalar_Static_Int32` (read raw, read processed/Average) |
**2** passing |
### Local validation
- `dotnet build UA.slnx -c Release` → **0 errors**.
- All historian / client integration / AOT history tests **green**.
### Hardening applied post-internal-review
- `DiagnosticsNodeManager.RollUpHistorianCapabilitiesAsync` — true async
(no more `.GetAwaiter().GetResult()` on the startup path).
- `HistoryClient` raw/modified/details readers — `try/finally` releases
the in-flight continuation point on `break`/exception/cancellation; also
detects malformed-server empty-page loops.
- `ReportAudit*` helpers gated on `HasAnyGood(...)` — audit events do
not fire when every per-value op failed.
- `ServerSystemContext` ctors throw
`ArgumentNullException(nameof(server))` at the boundary.
- `HistorianEventFilterTarget.IsTypeOf` logs a one-shot warning when
`IFilterContext.TypeTree` is null (degrades safely instead of silently).
- `InMemoryHistorianProvider.ReadEventsAsync` snapshots under lock,
filters outside (cuts lock-hold time).
- `TryRestoreContinuation` rejects cross-wired continuation points
(different `NodeId`).
- Processed-read framework fallback capped at 100 000 buffered outputs
(`BadTooManyOperations` when exceeded).
- ReferenceServer / TestData seeding is async-awaited /
`Task.Run`-bridged to escape any captured `SynchronizationContext`.
## Related Issues
- Fixes #
## Types of changes
- [x] Bugfix (non-breaking change which fixes an issue)
- [x] Enhancement (non-breaking change which adds functionality)
- [x] Test enhancement (non-breaking change to increase test coverage)
- [ ] Breaking change
- [x] Documentation Update
> The deletion of legacy
`Applications/Quickstarts.Servers/TestData/HistoryArchive*` is a
refactor of sample code only; the public stack surface is purely
additive.
## Checklist
- [x] I have read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [x] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf).
- [x] I ran tests locally with my changes, all passed.
- [ ] I fixed all failing tests in the CI pipelines.
- [ ] I fixed all introduced issues with CodeQL and LGTM.
- [x] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added necessary documentation (`Docs/HistoricalAccess.md`).
- [x] Any dependent changes have been merged and published in downstream
modules.
## Further comments
The provider model is intentionally minimal and orthogonal — providers
opt into specific Part 11 features by implementing one or more of the
narrow capability interfaces, and the dispatcher type-tests the concrete
provider at runtime. This keeps the bundled `InMemoryHistorianProvider`
simple while making it trivial for vendors to plug in their own
time-series database.
A few items remain explicitly deferred (documented in
`Docs/HistoricalAccess.md` *Limitations and roadmap*):
`HistoricalEventConfigurationType` auto-install for event notifiers,
audit-event `OldValues` fidelity (would require read-before-write across
update sites), true streaming processed-read continuation (the framework
fallback is bounded by the 100 k cap; native
`IHistorianProcessedProvider` providers already get arbitrary paging).
These are on-demand items, not gaps in the mandatory Part 11 surface.
* New certificate and secrete abstraction with certificate infrastructure and certificate/secret stores.
* leak testing for certificate resources to validate new ref counting in every test assembly
* Migration guide updated and documentation added for all
* Remove IDisposable from Nodestate and UserIdentity.
* UserCertificateTokenHandler now just points into certificate registry/stores, no dispose required
* Fix CA2000 warnings and cleanup of other diagnostics, increase warning levels in .editorconfig
* make most ptojects aot compatible
* Remove newtonsoft
* Migrate all projects from Mono.Options to System.CommandLine 2.0.5
* Fix array clone
* Replace serializers for storage using new attribute driven type geberator
* Add new AOT integration tests covering all functional areas
* Documentation updates
Generate stack and application code using source generators
Change built in types to readonly structs
Update localized text implementation to use JSON text serializer
Status code with symbolic names
Immutable node ids
No boxing for all built in types <= 8 bytes in Variant.
Split user identity token and token handling via token handler
Add migration guide for breaking changes
This pull request modernizes the OPC UA .NET codebase and tests, removes .NET Standard 2.0 support from certificate/security code, and updates test code to use C# 12 and .NET 8+ features for clarity and maintainability.
- Certificate and BouncyCastle interop files (e.g., CertificateBuilder.cs, X509Extensions.cs, X509SignatureFactory.cs) are refactored to drop NETSTANDARD2_0 support and use modern .NET APIs and conditional compilation.
- Test code across the codebase is updated to use default, strongly-typed Parse methods, collection expressions, and improved async/await patterns.
- Exception handling and assertions in tests are modernized, and test method naming is made consistent with Async suffixes.
- The project and build files are updated to clarify Roslynator analyzer usage and remove obsolete netstandard tags.
- General code and test cleanup includes improved null safety, type safety, and removal of deprecated or unused code.
Three new DataTypes plus Variables containing them were added to the Reference Server:
- VectorUnion (as Scalar and Array): The VectorUnion contains three fields (X, Y, Z) and a SwitchField. When it is used as value, it is generated randomly (SwitchField set to None or one of the Fields)
- VectorWithOptionalFields (as Scalar and Array): The VectorWithOptionalFields contains again three fields (X, Y, Z), but they are all optional. When it is used as a value, it is generated with 0 to all fields activated.
- MultipleVectors (as Scalar and Array): The MultipleVectors type contains 6 Components. A regular Vector, a VectorUnion (from before), a VectorWithOptionalFields (also from before) and the same as Arrays.
- Issue fix: Currently when diagnostics is enabled in client calls, the string table in the response header is not updated when a service call is split into multiple service calls. In this case the stringtables from all calls must be appended and the index in the diagnosticinfo must be updated to match the updated string list.
- To reduce the number of 'null' DiagnosticInfo allocations, the decoders now try to return null instead of a default DiagnosticInfo. A new property ÌsNullDiagnosticInfo' can be used to check for unused DiagnosticInfo entries.
- The tests were slightly improved to use test set data from the generated TestData namespace, which contains also a historical node.
- All `ServerFixtureUtils.ValidateXXX` checks were updated to include the check for diagnosticInfos and the string tables to catch issues.
- The StructureValue DataType value has a Method and event as childs, but it may only have variables / properties.
- Uses latest generated code from Modelcompiler which fixes issues with child variables read/write/monitoring.
- support for Microsoft.Extensions.Logger.ILogger in Opc.Ua.Core as the new logging interface
- backward compatible with config and TraceEvents
- new API Utils.SetLogger allows to set ILogger
- updated Console samples to demonstrate ILogger support with Serilog
- support for EventSource logging
- see Docs/Logging.md for more info
Marc Schier