Item 1: IHistorianDataSource.MaxRawValuesPerRead (Gateway: learned ceiling - 16 = L; 0 elsewhere, guard-tested).
RawPageLimit plans every raw page on top of #692's lookahead: with L > 0 the read (page P + boundary ties k
+ lookahead) is <= L, P = min(N, L - k - 1) (uncapped: L - k - 1); no room => straight to the tie-cluster
over-fetch (never an uncapped or underflowing request). One re-plan + re-read when the read taught a new
limit or was refused for crowding pre-window rows (HistoryReadLimitExceededException.PreWindowRows): the
page shrinks by them. Over-fetch bound min(MaxTieClusterOverfetch, L - 1); slice size never 0.
Review fixes: F1 a window starting at/before the epoch counts AVEVA's synthetic row as pre-window (a
ceiling-truncated read was reported complete); F2 the page path disables ReverseRawReader's own re-run
(cold end-only ceiling 20/N=3000 cost 3,023 reads, now <= 40); F3 crowded look-back re-read around, not
refused; F4 the #687 crowding re-read room at least doubles (up to 8 re-reads), so a cluster of hundreds
just before a resume point no longer fails on a default gateway; a crowding refusal that leaves no room
is BadTooManyOperations, never a tick-by-tick cursor.
Item 2: ServerHistorian:EventReadHorizon (default 00:00:00 = exact, unchanged). When set, every fresh
HistoryReadEvents window's earlier bound is raised to now - horizon (both directions, all backends).
Lossy by design; documented.
Item 3 (native TimeAverage/Total re-check) stays blocked on historiangw#27.
The null source has no history in either direction; reporting false
made the server walk an empty reverse events read back through three
empty forward reads. It now answers the reverse overload with the empty
result itself (guard test unchanged: it still declares both members).
#669 turned an end-only capped HistoryRead-Raw into a reverse read (start > end)
for every backend; the gateway rejects start > end (InvalidArgument), so on the
default Gateway backend every end-only capped and every explicit reverse raw read
failed the node and was counted as a backend health failure.
- IHistorianDataSource.SupportsReverseRaw (default false; SqlServer/QuestDB/Null
true, Gateway false; guard test pins that every production backend declares it).
- OtOpcUaNodeManager sends a reverse window only to a backend that declares it;
otherwise ReverseRawReader walks (lo, hi] back in bounded forward segment reads
(1 min, x4 while sparse; each <= MaxTieClusterOverfetch + 1 rows; a full read is
re-read narrower, never answered truncated; filtered on sample timestamps, which
also drops AVEVA's fabricated query-start rows; stops at the Unix epoch). A
one-timestamp tie cluster over the bound => BadTooManyOperations.
- ServeRawPagedAsync maps HistoryReadLimitExceededException to BadTooManyOperations.
- GatewayHistorianDataSource.ReadRawAsync refuses start > end unsent, without
recording a health failure.
IHistorianDataSource.SupportedAggregates (default: every HistoryAggregateType)
is the one authority for both ServerCapabilities/AggregateFunctions (i=2997) and
HistoryServerCapabilities/AggregateFunctions (i=11201) and for the up-front
BadAggregateNotSupported in HistoryRead-Processed. Gateway declares
AggregateModeMapper.Served (4), SqlServer/QuestDB AggregateFamilies.Served (17),
Null none. Only the folder references are trimmed; the SDK's calculator
factories stay so live AggregateFilter subscriptions keep working.
Co-Authored-By: Claude <noreply@anthropic.com>
- IHistorianDataSource.SupportsReverseEvents (default false; SqlServer/QuestDB true; Gateway/Null declare false).
The node manager checks it BEFORE calling the source: an end-only capped events read becomes reverse only on
a supporting backend (Gateway, the default, keeps the pre-#675 forward [MinValue, EndTime) paging), and an
explicit reverse read on a non-supporting backend is BadHistoryOperationUnsupported without a call.
- Removed the broad catch (NotSupportedException) in the events path: a NotSupportedException from inside a
backend is now logged as a backend fault (Error), not an 'unsupported' Warning.
- Null declares the reverse overload itself; guard test: every production IHistorianDataSource declares both
the reverse overload and the capability (positive-control scan of all four backends).
- Conformance: capability reported + oversized reverse tie cluster (forward over-fetch reversed == reverse
read order; capped reverse read stopping inside the cluster flags truncation) on SqlServer + QuestDB.
- docs/Historian.md: end-only capped events read is backward on SqlServer/QuestDB, forward on Gateway.
- IHistorianDataSource.ReadEventsAsync(..., bool reverse, ...) overload: reverse = Part 11 window (lo, hi]
newest-first by (time, id) DESC. Default forwards forward reads and throws NotSupportedException for
reverse (Null); Gateway refuses explicitly (ascending-only stream). Server answers
BadHistoryOperationUnsupported instead of silently returning the earliest N ascending.
- SqlServer / QuestDB serve reverse natively (ORDER BY time DESC, id DESC + TOP/LIMIT).
- Node manager: reverse event reads page with continuation points; direction stored in the cursor
(HistoryContinuationState.Reverse) so a resume continues in the cursor's direction; reverse tie clusters
over-fetched forward and sliced from the newest end (SliceTieCluster(reverse:)); end-only reads with a
cap page backward from EndTime (mirrors raw).
- Resumed event pages over-fetch by the boundary skip, so every non-final page is a full cap page.
- Tests: node-manager reverse paging (ties, clusters, coarse resolution, overfetch bound, resume
direction both ways, end-only, unsupported backend); shared EventReadConformance on SqlServer +
QuestDB; over-the-wire reverse paging; offline Gateway pin of the UTC DateTime.MaxValue bound through
the published client's proto conversion (in-process gRPC capture) and FILETIME.
- docs/Historian.md event paging section.
HistoryRead is served server-side by IHistorianDataSource; nothing ever dispatched
to a driver's IHistoryProvider. Removes IHistoryProvider, the OpcUaClient history
passthrough, DriverCapability.HistoryRead (+ resilience tier rows and AdminUI row),
HistoryReadStatusException and its node-manager catches, and the tests that only
covered them. Shared result types and HistoryAggregateNotSupportedException stay
(moved to Historian/HistoryReadContracts.cs). A stored ResilienceConfig still
carrying a HistoryRead key parses (diagnostic only; new test).
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Re-review at 7286d320. Core.Abstractions-009: ReadEventsAsync maxEvents<=0 sentinel now
documents the implementer's continuation-point obligation when a backend cap truncates
(the root of OpcUaServer-002). -010: PollGroupEngineTests pass CancellationToken. Plus
EquipmentTagRefResolver.TryResolve [MaybeNullWhen(false)] NRT cleanup + test.
Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.
- Core.Abstractions-004: guard DriverTypeRegistry.Register with a Lock so
concurrent registrations are atomic.
- Core.Abstractions-005: narrow PollGroupEngine catch blocks to non-fatal
exceptions, add optional onError callback, tolerate disposed-CTS races.
- Core.Abstractions-006: document the deliberate int-vs-uint asymmetry on
IHistoryProvider.ReadEventsAsync / IHistorianDataSource.ReadEventsAsync.
- Core.Abstractions-007: pin the gaps with PollGroupEngine + DriverHealth
contract tests.
- Core.Abstractions-008: correct XML docs on DriverHealth.LastError and
the optional / required asymmetry on the history-read surfaces.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.
- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
integration, install).
Build green (0 errors); unit tests pass. Docs left for a separate pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty