diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/HistoryPaging.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/HistoryPaging.cs
index 36172326..3dc4ab79 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/HistoryPaging.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/HistoryPaging.cs
@@ -1,3 +1,5 @@
+using Opc.Ua;
+using Opc.Ua.Server;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
namespace ZB.MOM.WW.OtOpcUa.OpcUaServer;
@@ -110,16 +112,51 @@ internal enum HistoryCursorKind
/// NumValuesPerNode samples with a null continuation point — so paging is synthesised here,
/// time-based:
///
-/// - A page that returns EXACTLY the requested cap (NumValuesPerNode > 0) MAY have
-/// more behind it ⇒ emit a continuation point.
-/// - A short page (fewer than the cap) is the last page ⇒ no continuation point.
-/// - NumValuesPerNode == 0 means "all values, no limit" (OPC UA Part 11) ⇒ never page;
-/// return everything in one shot.
+/// - A page whose read returned the lookahead row past it MAY have more behind it ⇒ emit a continuation
+/// point ( judges a read against what was asked for).
+/// - A short read (no lookahead row) is the last page ⇒ no continuation point.
+/// - NumValuesPerNode == 0 means "all values" (OPC UA Part 11) — but not "in one shot": the page is
+/// sized to the backend's by
+/// (the server raw cap ServerHistorian:MaxRawValuesPerRead, default 10 000, and/or a strict gateway's
+/// learned ceiling; review R08:1.1, #736), and a full page carries a continuation point like any other. Only
+/// with no limit at all (0, the opt-out) is everything returned in one shot.
///
-/// All methods are static + pure so they unit-test without a server, a session, or the SDK.
+/// All paging methods are static + pure so they unit-test without a server, a session, or the SDK;
+/// is the one SDK-facing member.
///
internal static class HistoryPaging
{
+ ///
+ /// Advertise the server raw cap as HistoryServerCapabilities/MaxReturnDataValues (i=11273; Part 11 §5.4.2:
+ /// "the maximum number of values that can be returned by the Server for each Node", 0 = no limit). The cap is
+ /// the most values one HistoryRead-Raw page returns (ServerHistorian:MaxRawValuesPerRead), so a client can
+ /// size its NumValuesPerNode and expect a continuation point past it. Idempotent; a re-sync with a
+ /// different cap overwrites. Never throws: a missing diagnostics manager or node leaves the SDK default (0) and
+ /// returns false — HistoryRead itself still enforces the cap.
+ ///
+ /// The running server.
+ /// The cap (<= 0 advertises 0 = no limit).
+ /// true when the property was written.
+ public static bool AdvertiseMaxReturnDataValues(IServerInternal? server, int maxRawValuesPerRead)
+ {
+ if (server?.DiagnosticsNodeManager is not DiagnosticsNodeManager diagnostics) return false;
+ try
+ {
+ lock (diagnostics.Lock)
+ {
+ var capabilities = diagnostics.GetDefaultHistoryCapabilities();
+ if (capabilities?.MaxReturnDataValues is not { } property) return false;
+ property.Value = (uint)Math.Max(0, maxRawValuesPerRead);
+ property.ClearChangeMasks(diagnostics.SystemContext, false);
+ return true;
+ }
+ }
+ catch (ServiceResultException)
+ {
+ return false;
+ }
+ }
+
///
/// Decide whether a just-returned page is "full" and therefore MAY be followed by more data —
/// the signal to emit a continuation point. A page is full when the client asked for a finite
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/RawPageLimit.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/RawPageLimit.cs
index 3adb40db..e4af5d11 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/RawPageLimit.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/RawPageLimit.cs
@@ -11,17 +11,22 @@ internal readonly record struct RawPagePlan(int Limit, uint PageCap, uint Reques
///
/// sizes a HistoryRead-Raw page to what the backend can return in one read
-/// ( = L — a strict HistorianGateway's learned row ceiling, less
-/// its boundary-row allowance). With a limit the read — page P + boundary ties k + the lookahead row — is at most L,
-/// so P = min(want, L − k − 1) (all values: P = L − k − 1); a full page carries a continuation point like any other, as
-/// Part 11 allows fewer values than NumValuesPerNode with one. Previously a cap above a strict gateway's ceiling
-/// (or an uncapped read of a window holding more) failed BadTooManyOperations.
+/// ( = L — the server raw cap
+/// ServerHistorian:MaxRawValuesPerRead, default 10 000, which every backend reports (review R08:1.1, #736),
+/// and/or a strict HistorianGateway's learned row ceiling less its boundary-row allowance, whichever is lower). With
+/// a limit the read — page P + boundary ties k + the lookahead row — is at most L, so P = min(want, L − k − 1) (all
+/// values: P = L − k − 1, i.e. a first page of 9 999 at the default cap); a full page carries a continuation point like
+/// any other, as Part 11 allows fewer values than NumValuesPerNode with one. Previously a cap above a strict
+/// gateway's ceiling (or an uncapped read of a window holding more) failed BadTooManyOperations, and before
+/// #736 an uncapped read on a backend without a ceiling read the whole window in one shot.
///
///
///
/// Never a silent truncation. The backend still answers a read in full or refuses it; only the server's page is
/// smaller, and a page is judged full against what was asked for. A read the backend cannot serve at all (a tie
-/// cluster larger than one read) stays BadTooManyOperations.
+/// cluster larger than one read) stays BadTooManyOperations. The backends enforce the same cap themselves
+/// (a read asking for more than L, or for everything, is refused when the window holds more than L rows), so this
+/// planner is what keeps the server's own reads inside it: with L > 0 no read it plans ever asks for 0 or more than L.
///
///
/// One re-read, planned again. A refused read () is re-planned and
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
index 1835c5ef..ba2fe9c7 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
@@ -158,10 +158,12 @@ public sealed class ServerHistorianOptions
public const int DefaultMaxRawValuesPerRead = 10_000;
///
- /// The smallest usable : a read must carry a page of at least one value AND the
- /// lookahead row that tells the server more data follows, so a cap of 1 is raised to 2 ().
+ /// The smallest usable : a resumed page's read must carry at least one value, the
+ /// boundary tie it re-reads and trims, AND the lookahead row that tells the server more data follows. At 2 a resumed
+ /// page has no room at all and every value costs an empty page with a continuation point (the #692 defect, re-created
+ /// by configuration), so 1 and 2 are raised to 3 ().
///
- public const int MinMaxRawValuesPerRead = 2;
+ public const int MinMaxRawValuesPerRead = 3;
///
/// Every backend: the most raw values the server returns on ONE HistoryRead-Raw page, and the most rows one
@@ -175,8 +177,10 @@ public sealed class ServerHistorianOptions
/// and is REFUSED (BadTooManyOperations) when the window holds more — never answered truncated — so a caller that
/// bypasses the node manager's paging cannot bypass the bound. On the Gateway backend a strict gateway's learned row
/// ceiling (less its boundary-row allowance) still applies when lower. The tie-cluster bound of a resumed page is also
- /// at most cap − 1 (as under a gateway ceiling; above that is inert). Default
- /// 10 000. Non-positive = unbounded, the pre-#736 behaviour (a warning); 1 is raised to 2.
+ /// at most cap − 1 (as under a gateway ceiling; above that is inert), and a
+ /// page whose boundary tie cluster is that large steps past it with one empty page. Default 10 000. Non-positive =
+ /// unbounded, the pre-#736 behaviour (a warning); below
+ /// (3) is raised to it.
///
public int MaxRawValuesPerRead { get; init; } = DefaultMaxRawValuesPerRead;
@@ -243,7 +247,7 @@ public sealed class ServerHistorianOptions
if (MaxRawValuesPerRead <= 0)
warnings.Add($"ServerHistorian:MaxRawValuesPerRead is {MaxRawValuesPerRead} — must be > 0; HistoryRead-Raw pages and backend raw reads are unbounded, so a client asking for a whole window (NumValuesPerNode = 0) materialises every sample in memory.");
else if (MaxRawValuesPerRead < MinMaxRawValuesPerRead)
- warnings.Add($"ServerHistorian:MaxRawValuesPerRead is {MaxRawValuesPerRead} — must be at least {MinMaxRawValuesPerRead} (a page plus its lookahead row); treated as {MinMaxRawValuesPerRead}.");
+ warnings.Add($"ServerHistorian:MaxRawValuesPerRead is {MaxRawValuesPerRead} — must be at least {MinMaxRawValuesPerRead} (a value, its boundary tie and the lookahead row); treated as {MinMaxRawValuesPerRead}.");
if (EventReadHorizon < TimeSpan.Zero)
warnings.Add($"ServerHistorian:EventReadHorizon is {EventReadHorizon} — negative is treated as no horizon (00:00:00); HistoryReadEvents reads every window in full.");
if (HistoryReadDeadline <= TimeSpan.Zero)
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/HistoryServerCapabilitiesAdvertisementTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/HistoryServerCapabilitiesAdvertisementTests.cs
new file mode 100644
index 00000000..0aaca5b1
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/HistoryServerCapabilitiesAdvertisementTests.cs
@@ -0,0 +1,58 @@
+using Opc.Ua;
+using Opc.Ua.Server;
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;
+
+///
+/// R08:1.1 (#736): the server raw cap (ServerHistorian:MaxRawValuesPerRead) is advertised as
+/// HistoryServerCapabilities/MaxReturnDataValues (i=11273) through ,
+/// read back the way a client would — through the SDK master node manager — over a real server.
+///
+public sealed class HistoryServerCapabilitiesAdvertisementTests(BoundsServerFixture fx) : IClassFixture
+{
+ private async Task ReadAdvertisedAsync()
+ {
+ var context = new OperationContext(new RequestHeader(), secureChannelContext: null, RequestType.Read, identity: null);
+ var nodesToRead = new ReadValueIdCollection
+ {
+ new ReadValueId { NodeId = VariableIds.HistoryServerCapabilities_MaxReturnDataValues, AttributeId = Attributes.Value },
+ };
+ var (values, _) = await fx.Nm.Server.NodeManager.ReadAsync(context, 0, TimestampsToReturn.Neither, nodesToRead, TestContext.Current.CancellationToken);
+ values.Count.ShouldBe(1);
+ StatusCode.IsGood(values[0].StatusCode).ShouldBeTrue(values[0].StatusCode.ToString());
+ return (uint)values[0].Value;
+ }
+
+ [Fact]
+ public async Task The_cap_is_advertised_as_MaxReturnDataValues_and_a_re_sync_overwrites_it()
+ {
+ await fx.Gate.WaitAsync(TestContext.Current.CancellationToken);
+ try
+ {
+ HistoryPaging.AdvertiseMaxReturnDataValues(fx.Nm.Server, 10_000).ShouldBeTrue();
+ (await ReadAdvertisedAsync()).ShouldBe(10_000u);
+
+ HistoryPaging.AdvertiseMaxReturnDataValues(fx.Nm.Server, 2_500).ShouldBeTrue();
+ (await ReadAdvertisedAsync()).ShouldBe(2_500u);
+
+ // Unbounded (the opt-out) advertises Part 11's "no limit".
+ HistoryPaging.AdvertiseMaxReturnDataValues(fx.Nm.Server, 0).ShouldBeTrue();
+ (await ReadAdvertisedAsync()).ShouldBe(0u);
+ HistoryPaging.AdvertiseMaxReturnDataValues(fx.Nm.Server, -5).ShouldBeTrue();
+ (await ReadAdvertisedAsync()).ShouldBe(0u);
+ }
+ finally
+ {
+ HistoryPaging.AdvertiseMaxReturnDataValues(fx.Nm.Server, 0);
+ fx.Gate.Release();
+ }
+ }
+
+ [Fact]
+ public void No_server_is_a_quiet_false()
+ {
+ HistoryPaging.AdvertiseMaxReturnDataValues(null, 10_000).ShouldBeFalse();
+ }
+}
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerHistoryReadRawCapFuzzTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerHistoryReadRawCapFuzzTests.cs
new file mode 100644
index 00000000..eb64ef64
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerHistoryReadRawCapFuzzTests.cs
@@ -0,0 +1,436 @@
+using Opc.Ua;
+using Opc.Ua.Server;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using HistorianRead = ZB.MOM.WW.OtOpcUa.Core.Abstractions.HistoryReadResult;
+using SdkHistoryReadResult = Opc.Ua.HistoryReadResult;
+
+namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;
+
+///
+/// R08:1.1 (#736): the paged-vs-unpaged fuzz for the server raw cap. Every paging change in this repo has had boundary
+/// bugs that the hand-written cases missed (silent truncation, an endless cursor, an empty page between every value), so
+/// the cap is proved the only way that has worked: random series (bursts, gaps, sub-millisecond stamps, tie clusters),
+/// random windows (empty, on a tie, one step past a tie, between samples, forward / reverse / end-only, with and without
+/// bounds) and random caps — NumValuesPerNode 0 / 1 / 2 / small / huge, the server cap 2 … 1000 or off, the
+/// tie-cluster budget 3 / 8 / 65536 — paged through a REAL SDK node manager against a wire-faithful fake of each backend
+/// (SqlServer: tick precision, native reverse, TOP; QuestDB: µs truncation of bounds AND stamps, native reverse,
+/// LIMIT; Gateway: forward only, [start, end) after its own boundary-row filtering, walked back by the
+/// server) that enforces the backend half of the cap exactly as the real sources do (a read asking for 0 or more than
+/// the cap reads cap + 1 rows and is refused when the window holds more).
+///
+/// The oracle is the same node manager's one-shot answer with the cap OFF (NumValuesPerNode = 0, no limit),
+/// which for a plain read is also checked against the series itself. The concatenation of the pages must equal it
+/// exactly; the read must terminate within the number of values plus two pages; no page may exceed the cap; the fake
+/// must never see a request for 0 or more than the cap (the "bounded by the same cap" invariant); and a
+/// BadTooManyOperations is accepted only when a tie cluster (or, on the Gateway shape, one millisecond) is
+/// larger than the budget that the cap and MaxTieClusterOverfetch leave — after an exact prefix. The run is
+/// non-vacuous by construction: it asserts that empty windows, mid-tie windows, reverse reads, caps of 1 and 2 and
+/// every shape occurred, and that most iterations were exact.
+///
+///
+/// Iterations: OTOPCUA_PAGING_FUZZ_ITERATIONS (default 10 000, the lane gate). Seeds are stable, so a failure
+/// names a reproducible seed.
+///
+///
+public sealed class NodeManagerHistoryReadRawCapFuzzTests(BoundsServerFixture fx) : IClassFixture
+{
+ private static readonly DateTime T0 = new(2026, 10, 22, 12, 0, 0, DateTimeKind.Utc);
+
+ /// The backend the fake is shaped like.
+ public enum Shape { SqlServer, QuestDb, Gateway }
+
+ private enum Direction { Forward, Reverse, EndOnly }
+
+ private static int Iterations =>
+ int.TryParse(Environment.GetEnvironmentVariable("OTOPCUA_PAGING_FUZZ_ITERATIONS"), out var n) && n > 0 ? n : 10_000;
+
+ [Fact]
+ public async Task Paged_equals_unpaged_on_random_series_windows_and_caps_and_always_terminates()
+ {
+ var iterations = Iterations;
+ var counts = new Dictionary();
+ void Count(string key) => counts[key] = counts.GetValueOrDefault(key) + 1;
+
+ await fx.Gate.WaitAsync(TestContext.Current.CancellationToken);
+ try
+ {
+ for (var seed = 0; seed < iterations; seed++)
+ {
+ var rng = new Random(seed);
+ var shape = (Shape)(seed % 3);
+ var resolution = shape == Shape.QuestDb ? 10L : 1L;
+ var series = RandomSeries(rng, resolution);
+ var cap = rng.Next(10) switch { 0 => 0, 1 or 2 => 3, 3 => 4, 4 => 5, 5 => 7, 6 => 10, 7 => 16, 8 => 33, _ => 1000 };
+ var n = rng.Next(9) switch { 0 or 1 => 0u, 2 or 3 => 1u, 4 or 5 => 2u, 6 => (uint)rng.Next(3, 20), 7 => (uint)rng.Next(20, 200), _ => 100_000u };
+ var tieBudget = rng.Next(4) switch { 0 => 3, 1 => 8, _ => 65536 };
+ var direction = rng.Next(5) switch { 0 => Direction.Reverse, 1 => Direction.EndOnly, _ => Direction.Forward };
+ if (direction == Direction.EndOnly && n == 0) direction = Direction.Forward; // Part 11: one bound only with a cap
+ var bounds = direction != Direction.EndOnly && rng.Next(4) == 0;
+
+ var a = PickBoundary(rng, series, resolution);
+ var b = PickBoundary(rng, series, resolution);
+ var (lo, hi) = a <= b ? (a, b) : (b, a);
+ var (start, end) = direction switch
+ {
+ Direction.Forward => (lo, hi),
+ Direction.Reverse => (hi, lo),
+ _ => (DateTime.MinValue, hi),
+ };
+ var tag = $"seed {seed} {shape} cap {cap} N {n} tie {tieBudget} {direction} bounds {bounds} [{start:O} .. {end:O}]";
+
+ // The walk-back (Gateway shape only: reverse / end-only reads, and the bound lookups of any bounded read) refuses
+ // a millisecond holding more samples than its budget — computed up front, over the whole series, because the
+ // walk and the lookups read around the window.
+ var walks = shape == Shape.Gateway && (direction != Direction.Forward || bounds);
+ var msMax = walks ? MillisecondMax(series) : 0;
+
+ // The oracle: the one-shot answer with the cap off (and, for a plain read, the series itself).
+ var truthSource = new CappedFake(series, shape, cap: 0);
+ fx.Nm.HistoricalSourceForTest(truthSource, tieBudget);
+ // An end-only read is paged backward from EndTime (the node manager flips it to a reverse read down to the
+ // beginning of time); its oracle is the explicit reverse read down to the Unix epoch — the walk-back's floor,
+ // and Part 11 (the SDK checks it) needs both bounds set when NumValuesPerNode = 0.
+ var (truth, truthError, truthCp) = direction == Direction.EndOnly
+ ? Read(hi, DateTime.UnixEpoch, 0, bounds: false, cp: null)
+ : Read(start, end, 0, bounds, cp: null);
+ if (truthError.StatusCode.Code == StatusCodes.BadTooManyOperations)
+ {
+ // Only the walk-back can refuse an uncapped one-shot read, and only past its budget (max(1, M) with no cap).
+ (walks && msMax > Math.Max(1, tieBudget)).ShouldBeTrue($"the oracle read was refused: {tag} (ms max {msMax})");
+ Count("oracle refused");
+ continue;
+ }
+ truthError.StatusCode.Code.ShouldBe(StatusCodes.Good, $"oracle: {tag}");
+ truthCp.ShouldBeNull($"oracle (no cap, N = 0) is one page: {tag}");
+ if (!bounds)
+ Render(truth).ShouldBe(Render(Oracle(series, start, end, direction, resolution)), $"oracle vs series: {tag}");
+ truthSource.OverCapRequests.ShouldBe(0, $"the uncapped oracle source must never be asked for more than it allows: {tag}");
+
+ var windowTies = LargestTieCluster(truth);
+ if (truth.Count == 0) Count("empty");
+ if (windowTies >= 2) Count("ties in window");
+ if (EndsOnTie(series, start, end, direction, resolution)) Count("window ends on a tie");
+ if (direction == Direction.Reverse) Count("reverse");
+ if (direction == Direction.EndOnly) Count("end-only");
+ if (n == 1) Count("N=1");
+ if (n == 2) Count("N=2");
+ if (n == 0) Count("N=0");
+ if (cap == 3) Count("cap=3");
+ if (bounds) Count("bounds");
+ Count(shape.ToString());
+
+ // A boundary tie cluster as large as the cap leaves a resumed page no room: the server steps past it with one
+ // empty page carrying a continuation point (the documented #694 ceiling behaviour) — the one empty page allowed.
+ var oversizedClusters = cap > 0
+ ? truth.Where(v => !(v.Value is null && v.StatusCode.Code == StatusCodes.BadBoundNotFound))
+ .GroupBy(v => v.SourceTimestamp.Ticks).Count(g => g.Count() >= Math.Max(2, cap - 1))
+ : 0;
+
+ // The read under test.
+ var source = new CappedFake(series, shape, cap);
+ fx.Nm.HistoricalSourceForTest(source, tieBudget);
+ var pages = new List>();
+ var collected = new List();
+ byte[]? cp = null;
+ StatusCode status;
+ do
+ {
+ var (values, error, next) = Read(start, end, n, bounds, cp);
+ status = error.StatusCode;
+ if (!StatusCode.IsGood(status)) break;
+ pages.Add(values);
+ collected.AddRange(values);
+ cp = next;
+ pages.Count.ShouldBeLessThanOrEqualTo(truth.Count + 2 + oversizedClusters, $"paging must terminate: {tag} pages {Sizes(pages)}");
+ }
+ while (cp is not null);
+
+ source.OverCapRequests.ShouldBe(0, $"the server asked the backend for 0 or more than the cap: {tag}");
+ source.BadRequests.ShouldBe(0, $"a reverse window reached a forward-only backend: {tag}");
+
+ if (status.Code == StatusCodes.BadTooManyOperations)
+ {
+ // Legitimate only past the budget the cap leaves: a tie cluster larger than min(M, cap − 1), or on the
+ // Gateway shape a millisecond holding more than min(M, cap − 2) samples (the walk-back's budget).
+ var overfetchBound = cap > 0 ? Math.Min(Math.Max(1, tieBudget), Math.Max(1, cap - 1)) : Math.Max(1, tieBudget);
+ var walkBudget = cap > 0 ? Math.Max(1, Math.Min(tieBudget, cap - 2)) : Math.Max(1, tieBudget);
+ var legit = windowTies > overfetchBound || (walks && msMax > walkBudget);
+ legit.ShouldBeTrue($"refused with no tie cluster over {overfetchBound} (max {windowTies}; ms max {msMax} vs {walkBudget}): {tag}");
+ Render(collected).ShouldBe(Render(truth.Take(collected.Count)), $"the prefix before the refusal: {tag}");
+ Count("refused");
+ continue;
+ }
+
+ status.Code.ShouldBe(StatusCodes.Good, $"{tag}");
+ Render(collected).ShouldBe(Render(truth), $"paged ≠ unpaged: {tag} pages {Sizes(pages)}");
+ if (cap > 0)
+ {
+ // A bounded read whose data fits one page carries its start bound, the data and its end bound: the node
+ // manager fits the end bound against the client's N but not against the server cap (follow-up F2), so that
+ // one page may hold cap + 1 values; every other page is at most the cap.
+ var bothBoundsOnOnePage = bounds && pages.Count == 1;
+ pages.ShouldAllBe(p => p.Count <= cap + (bothBoundsOnOnePage ? 1 : 0), $"a page over the cap: {tag} pages {Sizes(pages)}");
+ if (bothBoundsOnOnePage && pages[0].Count == cap + 1) Count("bounded single page at cap+1 (F2)");
+ }
+ if (n > 0) pages.ShouldAllBe(p => p.Count <= n, $"a page over N: {tag} pages {Sizes(pages)}");
+ for (var i = 0; i < pages.Count - 1; i++)
+ {
+ if (pages[i].Count > 0) continue;
+ // Allowed only as the step past a boundary tie cluster the cap cannot page within.
+ var previousLast = i > 0 && pages[i - 1].Count > 0 ? pages[i - 1][^1].SourceTimestamp.Ticks : (long?)null;
+ var clusterAtBoundary = previousLast is { } t ? truth.Count(v => v.SourceTimestamp.Ticks == t) : 0;
+ (cap > 0 && clusterAtBoundary >= Math.Max(2, cap - 1)).ShouldBeTrue(
+ $"an empty page with a continuation point (page {i}, boundary cluster {clusterAtBoundary}): {tag} pages {Sizes(pages)}");
+ Count("empty step over an oversized tie cluster");
+ }
+ if (pages.Count > 1) Count("paged");
+ if (pages.Count > 1 && n == 0) Count("paged at N=0");
+ // A cost guard against a read explosion, not a budget. A native shape reads once per page plus the bound
+ // lookups. The Gateway shape's walk-back has its own cost profile — ~30 reads a page on a dense tag
+ // (#691/#693), far more on a sparse series under a tiny tie budget (seed 320: 82 reads with NO cap, seed 6428:
+ // 120+) — so it is judged RELATIVE to the same request with the cap off (the pre-#736 behaviour), per page:
+ // the cap must not make the walk explode compared to before. The baseline asks for the page size the cap
+ // imposes (N = cap − 1): an uncapped N = 0 reverse read used to be ONE int.MaxValue forward read — the very
+ // memory vector the cap removes — so "what N = 0 cost before" is not the comparison.
+ var allowedReads = 8 * pages.Count + 8;
+ if (shape == Shape.Gateway)
+ {
+ var baseline = new CappedFake(series, shape, cap: 0);
+ fx.Nm.HistoricalSourceForTest(baseline, tieBudget);
+ var baseN = cap > 0 && (n == 0 || n > (uint)cap) ? (uint)(cap - 1) : n;
+ var basePages = 0;
+ byte[]? baseCp = null;
+ do
+ {
+ var (_, baseError, next) = Read(start, end, baseN, bounds, baseCp);
+ if (!StatusCode.IsGood(baseError.StatusCode)) break;
+ basePages++;
+ baseCp = next;
+ }
+ while (baseCp is not null && basePages <= truth.Count + 2 + oversizedClusters);
+ allowedReads = 2 * baseline.Reads * Math.Max(1, pages.Count) / Math.Max(1, basePages) + 32 * pages.Count + 16;
+ }
+ source.Reads.ShouldBeLessThanOrEqualTo(allowedReads,
+ $"backend reads exploded: {source.Reads} for {pages.Count} pages (allowed {allowedReads}): {tag}");
+ Count("exact");
+ }
+ }
+ finally
+ {
+ fx.Nm.HistoricalSourceForTest(NullHistorianDataSource.Instance, 65536);
+ fx.Gate.Release();
+ }
+
+ // Non-vacuous: every category the brief names occurred, and most runs were exact.
+ var summary = string.Join(", ", counts.OrderBy(kv => kv.Key).Select(kv => $"{kv.Key}={kv.Value}"));
+ foreach (var required in new[] { "empty", "ties in window", "window ends on a tie", "reverse", "end-only", "N=1", "N=2", "N=0", "cap=3", "bounds", "paged", "paged at N=0", "SqlServer", "QuestDb", "Gateway" })
+ counts.GetValueOrDefault(required).ShouldBeGreaterThan(iterations / 200, $"{required} under-represented: {summary}");
+ counts.GetValueOrDefault("exact").ShouldBeGreaterThan(iterations * 6 / 10, summary);
+ TestContext.Current.TestOutputHelper?.WriteLine($"raw-cap fuzz: {iterations} iterations — {summary}");
+ }
+
+ // --- generators -----------------------------------------------------------------------------
+
+ private static DateTime Ts(DataValueSnapshot s) => s.SourceTimestampUtc ?? DateTime.MinValue;
+
+ private static DateTime Trunc(DateTime t, long resolution) => new(t.Ticks - t.Ticks % resolution, DateTimeKind.Utc);
+
+ /// Random ascending series: bursts, gaps, sub-millisecond stamps and tie clusters; stamps stored at the resolution.
+ private static List RandomSeries(Random rng, long resolution)
+ {
+ var list = new List();
+ var t = T0.Ticks - rng.Next(0, 3) * TimeSpan.TicksPerHour;
+ var count = rng.Next(1, 120);
+ var v = 0;
+ while (list.Count < count)
+ {
+ t += rng.Next(6) switch
+ {
+ 0 => rng.Next(1, 10), // sub-millisecond (sub-µs on QuestDB: collapses onto a tie)
+ 1 => rng.Next(1, 5) * TimeSpan.TicksPerMillisecond, // dense
+ 2 => rng.Next(1, 3) * TimeSpan.TicksPerSecond,
+ 3 => rng.Next(1, 30) * TimeSpan.TicksPerMinute, // a gap
+ _ => rng.Next(1, 1000) * TimeSpan.TicksPerMillisecond,
+ };
+ var ties = rng.Next(7) == 0 ? rng.Next(2, 9) : 1;
+ for (var k = 0; k < ties; k++)
+ {
+ var ts = Trunc(new DateTime(t, DateTimeKind.Utc), resolution);
+ var status = rng.Next(12) == 0 ? StatusCodes.Bad : StatusCodes.Good;
+ list.Add(new DataValueSnapshot(status == StatusCodes.Bad ? null : (double)v, status, ts, ts));
+ v++;
+ }
+ }
+
+ return list;
+ }
+
+ /// A window bound: before / after the data, exactly on a sample (a tie, maybe), one step past one, a tick before one, or between two.
+ private static DateTime PickBoundary(Random rng, List series, long resolution)
+ {
+ var first = Ts(series[0]);
+ var last = Ts(series[^1]);
+ var i = rng.Next(series.Count);
+ var t = Ts(series[i]);
+ switch (rng.Next(9))
+ {
+ case 0: return first.AddSeconds(-rng.Next(1, 100));
+ case 1: return last.AddSeconds(rng.Next(1, 100));
+ case 2:
+ case 3: return t;
+ case 4: return t.AddTicks(resolution);
+ case 5: return t.AddTicks(-1); // sub-resolution: a microsecond backend truncates it back ONTO the sample
+ case 6: return t.AddMilliseconds(1);
+ default:
+ var next = i + 1 < series.Count ? Ts(series[i + 1]) : t.AddSeconds(10);
+ return new DateTime(t.Ticks + (long)((next.Ticks - t.Ticks) * rng.NextDouble()), DateTimeKind.Utc);
+ }
+ }
+
+ /// The series' own answer for a plain (no bounds) read: forward [start, end), point, reverse / end-only (end, start] newest first.
+ private static List Oracle(List series, DateTime start, DateTime end, Direction direction, long resolution)
+ {
+ var s = Trunc(start, resolution);
+ var e = Trunc(end, resolution);
+ IEnumerable window = direction switch
+ {
+ // start == end is Part 11's point read whichever way it was generated: the node manager reads it forward.
+ Direction.Forward or Direction.Reverse when s == e => series.Where(x => Ts(x) == s),
+ Direction.Forward => series.Where(x => Ts(x) >= s && Ts(x) < e),
+ Direction.Reverse => series.Where(x => Ts(x) > e && Ts(x) <= s).Reverse(),
+ _ => series.Where(x => Ts(x) <= e).Reverse(),
+ };
+ return window.Select(x => new DataValue(new Variant(x.Value), new StatusCode(x.StatusCode), Ts(x), Ts(x))).ToList();
+ }
+
+ /// The largest tie cluster among the returned stored values (a bound placeholder is not a stored value).
+ private static int LargestTieCluster(IReadOnlyList truth) =>
+ truth.Where(v => !(v.Value is null && v.StatusCode.Code == StatusCodes.BadBoundNotFound))
+ .GroupBy(v => v.SourceTimestamp.Ticks).Select(g => g.Count()).DefaultIfEmpty(0).Max();
+
+ /// The most samples within one millisecond anywhere in the series (the walk-back's refusal rule).
+ private static int MillisecondMax(List series)
+ {
+ var msMax = 0;
+ for (int i = 0, j = 0; i < series.Count; i++)
+ {
+ while (Ts(series[i]).Ticks - Ts(series[j]).Ticks >= TimeSpan.TicksPerMillisecond) j++;
+ msMax = Math.Max(msMax, i - j + 1);
+ }
+
+ return msMax;
+ }
+
+ private static bool EndsOnTie(List series, DateTime start, DateTime end, Direction direction, long resolution)
+ {
+ var edge = Trunc(direction == Direction.Forward ? end : direction == Direction.Reverse ? start : end, resolution);
+ return series.Count(x => Ts(x) == edge) >= 2;
+ }
+
+ // --- helpers ----------------------------------------------------------------------------------
+
+ private static string Sizes(IEnumerable> pages) => "[" + string.Join(",", pages.Select(p => p.Count)) + "]";
+
+ private static string Render(IEnumerable values) =>
+ string.Join(" | ", values.Select(v => $"{v.SourceTimestamp.Ticks}={v.Value ?? "null"}/{v.StatusCode.Code:X8}"));
+
+ private (IReadOnlyList Values, ServiceResult Error, byte[]? Cp) Read(DateTime start, DateTime end, uint max, bool bounds, byte[]? cp)
+ {
+ var context = new OperationContext(new RequestHeader(), secureChannelContext: null, RequestType.HistoryRead, identity: null);
+ var details = new ReadRawModifiedDetails
+ {
+ StartTime = start, EndTime = end, NumValuesPerNode = max, ReturnBounds = bounds, IsReadModified = false,
+ };
+ var nodesToRead = new List { new() { NodeId = fx.NodeId, ContinuationPoint = cp } };
+ var results = new List { null! };
+ var errors = new List { null! };
+ fx.Nm.HistoryRead(context, details, TimestampsToReturn.Both, releaseContinuationPoints: false, nodesToRead, results, errors);
+
+ var values = new List();
+ if (results[0]?.HistoryData is { } ho && !ExtensionObject.IsNull(ho))
+ values.AddRange(((HistoryData)ExtensionObject.ToEncodeable(ho)).DataValues);
+ return (values, errors[0], results[0]?.ContinuationPoint);
+ }
+
+ ///
+ /// A series-backed historian shaped like one backend, enforcing the backend half of the server raw cap exactly as
+ /// the real data sources do: it reports the cap as ; a read asking for 0 or more than
+ /// the cap reads cap + 1 rows and throws when the window holds more
+ /// (never a truncated answer). It also records every such request () — the server must
+ /// never issue one — and every reverse window sent to the forward-only shape ().
+ ///
+ private sealed class CappedFake(IReadOnlyList series, Shape shape, int cap) : IHistorianDataSource
+ {
+ private readonly Lock _gate = new();
+
+ public int Reads { get; private set; }
+ public int OverCapRequests { get; private set; }
+ public int BadRequests { get; private set; }
+
+ public bool SupportsReverseRaw => shape != Shape.Gateway;
+
+ public long TimestampResolutionTicks => shape == Shape.QuestDb ? 10 : 1;
+
+ public int MaxRawValuesPerRead => cap;
+
+ private DateTime Trunc(DateTime t) => NodeManagerHistoryReadRawCapFuzzTests.Trunc(t, TimestampResolutionTicks);
+
+ public Task ReadRawAsync(
+ string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode, CancellationToken cancellationToken)
+ {
+ var probe = cap > 0 && (maxValuesPerNode == 0 || maxValuesPerNode > (uint)cap);
+ lock (_gate)
+ {
+ Reads++;
+ if (probe) OverCapRequests++;
+ if (shape == Shape.Gateway && startUtc > endUtc) BadRequests++;
+ }
+
+ if (shape == Shape.Gateway && startUtc > endUtc)
+ throw new InvalidOperationException("start_time must be less than or equal to end_time. (InvalidArgument)");
+
+ startUtc = Trunc(startUtc);
+ endUtc = Trunc(endUtc);
+ List window;
+ if (startUtc > endUtc) window = series.Where(s => Ts(s) > endUtc && Ts(s) <= startUtc).Reverse().ToList();
+ else if (startUtc == endUtc) window = series.Where(s => Ts(s) == startUtc).ToList();
+ else window = series.Where(s => Ts(s) >= startUtc && Ts(s) < endUtc).ToList();
+
+ var top = probe ? cap + 1 : maxValuesPerNode == 0 ? int.MaxValue : (int)Math.Min(maxValuesPerNode, int.MaxValue);
+ var page = window.Take(top).ToList();
+ if (probe && page.Count > cap)
+ throw new HistoryReadLimitExceededException(cap, $"more than MaxRawValuesPerRead ({cap}) samples");
+ return Task.FromResult(new HistorianRead(page, null));
+ }
+
+ public Task ReadProcessedAsync(
+ string fullReference, DateTime startUtc, DateTime endUtc, TimeSpan interval,
+ HistoryAggregateType aggregate, CancellationToken cancellationToken) =>
+ Task.FromResult(new HistorianRead(Array.Empty(), null));
+
+ public Task ReadAtTimeAsync(
+ string fullReference, IReadOnlyList timestampsUtc, CancellationToken cancellationToken) =>
+ Task.FromResult(new HistorianRead(Array.Empty(), null));
+
+ public Task ReadEventsAsync(
+ string? sourceName, DateTime startUtc, DateTime endUtc, int maxEvents, CancellationToken cancellationToken) =>
+ Task.FromResult(new HistoricalEventsResult(Array.Empty(), null));
+
+ public HistorianHealthSnapshot GetHealthSnapshot() => NullHistorianDataSource.Instance.GetHealthSnapshot();
+
+ public void Dispose() { }
+ }
+}
+
+/// Test-only wiring shared by the paging fuzz: swap the source and the tie budget, with a fresh continuation store.
+internal static class NodeManagerFuzzExtensions
+{
+ public static void HistoricalSourceForTest(this OtOpcUaNodeManager nm, IHistorianDataSource source, int tieBudget)
+ {
+ nm.HistoryContinuationStore = new InMemoryHistoryContinuationStore();
+ nm.MaxTieClusterOverfetch = tieBudget;
+ nm.HistorianDataSource = source;
+ }
+}
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/RawPageLimitTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/RawPageLimitTests.cs
index fdd3e597..7818258d 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/RawPageLimitTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/RawPageLimitTests.cs
@@ -24,6 +24,15 @@ public sealed class RawPageLimitTests
[InlineData(5000u, 983, 984, 0u, 0u, true)] // the ties alone fill a read: never a 0 (uncapped) request
[InlineData(5000u, 5000, 984, 0u, 0u, true)] // never an underflow
[InlineData(5000u, 0, 1, 0u, 0u, true)]
+ // R08:1.1 (#736): the server raw cap (default 10 000) is the limit every backend reports — an uncapped read pages at it.
+ [InlineData(0u, 0, 10_000, 9_999u, 10_000u, false)] // NumValuesPerNode = 0: a first page of cap − 1 + the lookahead row
+ [InlineData(0u, 1, 10_000, 9_998u, 10_000u, false)] // a resumed page re-reads its one boundary tie
+ [InlineData(100_000u, 0, 10_000, 9_999u, 10_000u, false)] // a client cap above the server cap is bounded by it
+ [InlineData(10_000u, 0, 10_000, 9_999u, 10_000u, false)] // exactly the cap: still cap − 1 (the lookahead row needs room)
+ [InlineData(500u, 0, 10_000, 500u, 501u, false)] // under the cap: unchanged
+ [InlineData(0u, 0, 3, 2u, 3u, false)] // the smallest usable cap (MinMaxRawValuesPerRead = 3): a first page of two
+ [InlineData(0u, 1, 3, 1u, 3u, false)] // … and a resumed page still carries one value beside its boundary tie
+ [InlineData(0u, 1, 2, 0u, 0u, true)] // at 2 a resumed page has NO room — every value would cost an empty page (why 3 is the floor)
public void Plan_fits_page_ties_and_lookahead_into_the_limit(uint want, int k, int limit, uint page, uint request, bool noRoom)
{
var plan = RawPageLimit.Plan(want, k, limit);
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
index 8ad76302..08d700b2 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
@@ -208,18 +208,22 @@ public sealed class ServerHistorianOptionsTests
Assert.Contains("unbounded", m);
}
- [Fact]
- public void A_MaxRawValuesPerRead_of_one_is_raised_to_two_and_warns_when_enabled()
+ [Theory]
+ [InlineData(1)]
+ [InlineData(2)]
+ public void A_MaxRawValuesPerRead_below_three_is_raised_to_three_and_warns_when_enabled(int value)
{
- // One row per read cannot carry a page AND the lookahead row that says "more follows" — a fresh page would be refused.
+ // A resumed page's read must carry a value, the boundary tie it re-reads and the lookahead row that says "more
+ // follows": at 2 it has no room and every value costs an empty page with a continuation point (the #692 defect).
var o = new ServerHistorianOptions
{
- Enabled = true, Endpoint = "https://h:5222", ApiKey = "histgw_x_y", MaxRawValuesPerRead = 1,
+ Enabled = true, Endpoint = "https://h:5222", ApiKey = "histgw_x_y", MaxRawValuesPerRead = value,
};
- Assert.Equal(2, o.EffectiveMaxRawValuesPerRead);
+ Assert.Equal(3, o.EffectiveMaxRawValuesPerRead);
Assert.Equal(ServerHistorianOptions.MinMaxRawValuesPerRead, o.EffectiveMaxRawValuesPerRead);
var m = Assert.Single(o.Validate());
Assert.Contains("MaxRawValuesPerRead", m);
+ Assert.Equal(3, new ServerHistorianOptions { MaxRawValuesPerRead = 3 }.EffectiveMaxRawValuesPerRead);
}
[Fact]