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Marc Schier
fac30c45e6
# Description PR #4194 removed the unused `ServerConfiguration.MinMetadataSamplingInterval` and left nothing in its place. As a result there was no way to populate `Server.ServerCapabilities.MinSupportedSampleRate` (`i=2272`) — `ServerInternalData.CreateServerObjectAsync` hardcoded it to `0`. Separately, the only clamp applied when revising a monitored item's sampling interval was the per-node `BaseVariableState.MinimumSamplingInterval`, which defaults to `MinimumSamplingIntervals.Continuous` (`0`), so reference-server nodes accepted any requested interval (e.g. 10 ms) unrevised — exactly what was reported. This adds a configuration entry **in the exact schema slot #4194 vacated** and enforces it as a lower bound. ## Configuration - **`ServerConfiguration.MinSupportedSamplingInterval`** — `double` (milliseconds), default `0`, `[DataTypeField(Order = 17)]`, i.e. between `MaxNotificationsPerPublish` (16) and `AvailableSamplingRates` (18). - `ApplicationConfiguration.xsd` — `<xs:element name="MinSupportedSamplingInterval" type="xs:double" minOccurs="0" />` in the same position the removed element occupied. - Fluent API **`SetMinSupportedSamplingInterval(double)`** on `IApplicationConfigurationBuilderServerOptions`, in the place `SetMinMetadataSamplingInterval` was removed from. - The element is added to the six config XML files #4194 touched (reference / CTT / AOT / GDS use `0`; `test-server-full.xml` uses a distinctive non-zero value for the round-trip test). The address-space Property keeps its OPC UA spec name, so `Server.ServerCapabilities.MinSupportedSampleRate` and `VariableIds.Server_ServerCapabilities_MinSupportedSampleRate` are unchanged. ```xml <MaxNotificationsPerPublish>1000</MaxNotificationsPerPublish> <MinSupportedSamplingInterval>2000</MinSupportedSamplingInterval> <AvailableSamplingRates> ``` ```csharp application.Build(applicationUri, productUri) .AsServer([endpointUrl]) .SetMinSupportedSamplingInterval(2000); ``` ## Behavior - `ServerInternalData` now publishes the configured value to `Server.ServerCapabilities.MinSupportedSampleRate`. - New `SubscriptionManager.CalculateRevisedSamplingInterval(...)` (two overloads, alongside the existing `CalculateRevisedQueueSize`) centralizes the revision rule and replaces the logic that was duplicated across four call sites — the create and modify paths of `AsyncCustomNodeManager` and `CustomNodeManager` — which now expose a `MinSupportedSamplingInterval` property seeded from the configuration (mirroring how `MaxQueueSize` is initialized). The rule: 1. A requested interval below zero resolves to the *default sampling interval*: the **publishing interval of the subscription** on create, and the item's **current sampling interval** on modify. The modify case preserves 1.5.378 behavior, so a `ModifyMonitoredItems` call that leaves the sampling interval unspecified does not silently retune the item. 2. A node declaring `MinimumSamplingIntervals.Continuous` (`0`) for the `Value` Attribute reports **by exception** and is **not** bound by the server-wide minimum — the requested interval is returned unchanged. 3. Every other item is raised to `max(nodeMinimumSamplingInterval, MinSupportedSamplingInterval)`. Attributes other than `Value`, nodes declaring `MinimumSamplingIntervals.Indeterminate` (`-1`), and non-Variable nodes are bound only by `MinSupportedSamplingInterval`. 4. `double.MaxValue` is capped to one year (pre-existing behavior, now in one place). Event monitored items do not sample and are unaffected. **Backward compatible:** with the default of `0` the computation is identical to the previous code for every input, including `Continuous`, `Indeterminate`, positive node minimums, non-`Value` attributes and `NaN`. No existing configuration or deployment changes behavior. Node managers that implement `INodeManager` directly can call the new public helper to apply the same rule. ## Related Issues - Fixes #4191 The issue thread also asked whether `Subscription.MaxNotificationsPerPublish` is revised by the server. It is (`SubscriptionManager.CalculateMaxNotificationsPerPublish`), but it was untested and is not observable from the `CreateSubscription` response, which carries no revised field for that parameter. Four tests were added that assert it through `SubscriptionDiagnostics.MaxNotificationsPerPublish` on a privileged session, covering create and modify, the above-limit, below-limit and `0` (server default) cases. ## Tests - **`SamplingIntervalRevisionTests`** (17 unit tests, `Opc.Ua.Server.Tests`) — the full revision matrix: negative request resolving to the default interval, the `Continuous` bypass, `Indeterminate`, node minimum above *and* below the floor, a floor of `0` being a no-op, non-`Value` attributes, non-Variable and null nodes, and the `double.MaxValue` cap. - **`MinSupportedSamplingIntervalTests`** (10 integration tests, `Opc.Ua.Subscriptions.Tests`) — against a reference server configured with a 500 ms floor: the capabilities node reflects the configuration; a node declaring 100 ms is lifted to 500 ms; `Scalar_Static_Arrays2D_LocalizedText` (1000 ms) wins over the floor; `CurrentTime` (250 ms) is lifted; a `Continuous` node keeps its 10 ms; a non-`Value` attribute is floored; `ModifyMonitoredItems` behaves the same in both directions; event items are unaffected. - Restored the configuration builder and round-trip test coverage that #4194 deleted. - `TestFixture` gained a `protected virtual void ConfigureServer(ApplicationConfiguration)` hook so a derived fixture can vary the server configuration before start. Default implementation is a no-op, so no existing fixture changes behavior. ## Documentation - `docs/Subscriptions.md` — new **Sampling interval revision** section with the input table, the four-step rule (including both negative-interval fallbacks), XML and fluent configuration examples, and guidance for custom node managers. - `docs/migrate/2.0.x/configuration.md` — new section documenting that `MinMetadataSamplingInterval` was removed and `MinSupportedSamplingInterval` added. Verified against `master378`: the old setting defaulted to `1000` but was never read, and `MinSupportedSampleRate` was hardcoded to `0` with no server-wide floor. The guide therefore stresses that these are **two different settings, not a rename** — consumers should drop the old element (a default of `0` reproduces 1.5.378 exactly) and only opt into the new one deliberately, since reusing the old value would silently introduce a sampling floor. ## Validation - `dotnet build UA.slnx` — **0 warnings, 0 errors** across all TFMs. - .NET 10: `Opc.Ua.Server.Tests` 4091 passed, `Opc.Ua.Subscriptions.Tests` 619 passed (full suite including the new fixture), `Opc.Ua.InformationModel.Tests` 1063 passed, `Opc.Ua.Configuration.Tests` 221 passed, `Opc.Ua.Gds.Tests` 119 passed. - .NET Framework 4.8: new unit tests (200 incl. sampling groups), new integration tests (17) and configuration round-trip (135) all passed. - `ConsoleReferenceServer` starts successfully with the updated configuration file. ## 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. - [x] 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. - [x] I have addressed **all** PR feedback received. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 79f8090c-b2a3-409c-a5bf-56b6d2a35e70