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Auto: opcuaclient-13 — Part 13 aggregate catalog mapping

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Closes #285
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Joseph Doherty
2026-04-26 09:46:33 -04:00
parent 7cbc566db9
commit 0adc5adb59
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docs/drivers/OpcUaClient.md
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@@ -193,3 +193,68 @@ HistoryRead facade is responsible for round-tripping these so a paged event
read against a chatty upstream completes incrementally. The driver itself
doesn't track them — every `ReadEventsAsync` call issues a fresh
`HistoryReadAsync`.
## HistoryRead Aggregates (Part 13 catalog)
`IHistoryProvider.ReadProcessedAsync` takes a `HistoryAggregateType` and the
driver maps it to the standard `Opc.Ua.ObjectIds.AggregateFunction_*` NodeId
in `MapAggregateToNodeId`. PR-13 (issue #285) extended the enum from the
original 5 values (Average / Minimum / Maximum / Total / Count) to the full
OPC UA Part 13 §5 catalog — ~30 aggregates.
The mapping is best-effort: not every upstream OPC UA server implements every
aggregate. Aggregates the upstream rejects come back with
`StatusCode=BadAggregateNotSupported` on the per-row HistoryRead result; the
driver passes that through verbatim (cascading-quality rule, Part 11 §8) — it
does not throw. Servers advertise the aggregates they support via the
`AggregateConfiguration` object on the `Server` node; clients can probe it at
runtime.
### Catalog
| Enum value | SDK NodeId field | Part 13 § | Server-side support | Typical use |
| --- | --- | --- | --- | --- |
| `Average` | `AggregateFunction_Average` | §5.4 | almost always | smoothing |
| `Minimum` | `AggregateFunction_Minimum` | §5.5 | almost always | low watermark |
| `Maximum` | `AggregateFunction_Maximum` | §5.6 | almost always | high watermark |
| `Total` | `AggregateFunction_Total` | §5.10 | usually | totalisation |
| `Count` | `AggregateFunction_Count` | §5.18 | almost always | sample count |
| `TimeAverage` | `AggregateFunction_TimeAverage` | §5.4.2 | usually | time-weighted mean |
| `TimeAverage2` | `AggregateFunction_TimeAverage2` | §5.4.3 | sometimes | bounded time-weighted mean |
| `Interpolative` | `AggregateFunction_Interpolative` | §5.3 | usually | trend snapshot |
| `MinimumActualTime` | `AggregateFunction_MinimumActualTime` | §5.5.4 | sometimes | when low occurred |
| `MaximumActualTime` | `AggregateFunction_MaximumActualTime` | §5.6.4 | sometimes | when high occurred |
| `Range` | `AggregateFunction_Range` | §5.7 | usually | spread |
| `Range2` | `AggregateFunction_Range2` | §5.7 | sometimes | bounded spread |
| `AnnotationCount` | `AggregateFunction_AnnotationCount` | §5.21 | rarely | operator notes |
| `DurationGood` | `AggregateFunction_DurationGood` | §5.16 | sometimes | quality coverage |
| `DurationBad` | `AggregateFunction_DurationBad` | §5.16 | sometimes | gap accounting |
| `PercentGood` | `AggregateFunction_PercentGood` | §5.17 | sometimes | quality % |
| `PercentBad` | `AggregateFunction_PercentBad` | §5.17 | sometimes | gap % |
| `WorstQuality` | `AggregateFunction_WorstQuality` | §5.20 | sometimes | worst seen |
| `WorstQuality2` | `AggregateFunction_WorstQuality2` | §5.20 | rarely | bounded worst |
| `StandardDeviationSample` | `AggregateFunction_StandardDeviationSample` | §5.13 | sometimes | n-1 stddev |
| `StandardDeviationPopulation` | `AggregateFunction_StandardDeviationPopulation` | §5.13 | sometimes | n stddev |
| `VarianceSample` | `AggregateFunction_VarianceSample` | §5.13 | sometimes | n-1 variance |
| `VariancePopulation` | `AggregateFunction_VariancePopulation` | §5.13 | sometimes | n variance |
| `NumberOfTransitions` | `AggregateFunction_NumberOfTransitions` | §5.12 | sometimes | event count |
| `DurationInStateZero` | `AggregateFunction_DurationInStateZero` | §5.19 | sometimes | OFF time |
| `DurationInStateNonZero` | `AggregateFunction_DurationInStateNonZero` | §5.19 | sometimes | ON time |
| `Start` | `AggregateFunction_Start` | §5.8 | usually | first sample |
| `End` | `AggregateFunction_End` | §5.9 | usually | last sample |
| `Delta` | `AggregateFunction_Delta` | §5.11 | usually | end-start |
| `StartBound` | `AggregateFunction_StartBound` | §5.8 | sometimes | extrapolated start |
| `EndBound` | `AggregateFunction_EndBound` | §5.9 | sometimes | extrapolated end |
"Server-side support" is heuristic — see your upstream's `AggregateConfiguration`
node for the authoritative list. AVEVA Historian, KEPServerEX, Prosys, and
opc-plc each implement different subsets.
### Driver-side validation
The mapping itself is unit-tested over the full enum
(`OpcUaClientAggregateMappingTests`) — every value resolves to a non-null
namespace-0 NodeId, and the original 5 ordinals stay pinned. Wire-side
behaviour against a live server is exercised by
`OpcUaClientAggregateSweepTests` (build-only scaffold pending an opc-plc
history-sim profile).