Drove the revision-write flow via reflection in the native trace harness
(--write-revision-values) to see whether it bypasses the AddS2
architectural blocker. It doesn't.
Findings:
- HistorianAccess.CreateHistorianDataValueList(NonStreamedOriginal) succeeds
- HistorianDataValueList.NonStreamedValuesBegin() succeeds (batchID 0->1)
- HistorianDataValueList.AddNonStreamedValue(value, validate=true, out err)
FAILS with ErrorCode=TagNotFoundInCache (129) — same client-side
validation gate that blocks AddS2
- AddNonStreamedValuesEnd() returns void; SendValues() returns true
with Success because the list is empty (no value was ever added)
- No AddNonStreamValues* WCF calls reach the wire
Conclusion: the revision-write path requires the tag to be in the
library's runtime tag cache, which is only populated by configured
IO server / Application Server pipelines, not by HistorianAccess.AddTag.
This matches the architectural blocker documented for AddS2 and means
no public WriteRevisionsAsync / BeginRevisionAsync should be added to
the SDK — the path is unreachable for client-created sandbox tags.
The Wcf/Contracts/ITransactionServiceContract methods (AddNonStream-
ValuesBegin/AddNonStreamValues/AddNonStreamValuesEnd) remain declared
for completeness; no orchestrator or public surface is added.
The harness extension is preserved as a deterministic reproducer for
the blocker: re-run --write-revision-values to verify the gate any
time. docs/plans/revision-write-path.md updated with the empirical
finding plus the original plan retained as historical context.
177/177 tests still pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Plan: docs/plans/speculative-items-sweep.md (also covers parallelism +
findings).
Implemented:
- C3: HistorianTagDefinition.IntegralDivisor (default 1.0). Wire bytes
flip per the captured native serializer; live probe shows the server
stores IntegralDivisor on EngineeringUnit (shared) rather than per-tag,
so the value is accepted on the wire but doesn't visibly persist for
the test EU. Documented in the property's doc-comment.
- E: HistorianWcfCertOptionTests (5 tests) covering AllowUntrustedServer-
Certificate validator installation + ServerDnsIdentity propagation
through CreateEndpointAddress and CreateBindingPair.
Investigated + documented (deferred):
- D3: Discrete/String/Int1/Int8/UInt8 EnsT2 root cause — server-side
ValidationFailed: "Transaction validation failed". Native AddTag's
validator rejects non-analog types; not a wire-format issue. To unlock,
need to capture a working native flow via a different code path
(likely SMC's tag-import path or AddTagExtendedProperties carrying
type-specific metadata). Defer until a customer asks.
- D1: AddTagExtendedProperties feasibility — managed surface confirmed
(ArchestrA.HistorianAccess.AddTagExtendedProperties + WCF op
AddTagExtendedPropertyGroups). Cost estimated at 1-2 days of focused
RE work due to CTagExtendedPropertyGroup payload complexity. Defer.
- D2: AddRevisionValuesBegin/Value/End — sub-plan written at
docs/plans/revision-write-path.md with 5-step capture sequence,
workstream estimates, and risk register. Implementation deferred.
177/177 tests pass (was 172; +5 cert tests + 1 IntegralDivisor unit
test, harness probe results not committed).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty