HistoryRead returns BadHistoryOperationUnsupported when the historian backend is unreachable (should be a retryable communication status) #697

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2026-10-13T02:12:08-04:00

dohertj2 commented

2026-10-13 02:12:08 -04:00

Found by the #692–#694 live AVEVA gate (2026-10-13). A ~2 minute VPN drop hit one run. Pre-existing; affects every historian backend. Low/medium.

Symptom: while the backend (here the HistorianGateway → AVEVA path) is unreachable, HistoryRead Raw/Modified answers BadHistoryOperationUnsupported. That tells clients the node has no history at all and they should stop asking. The real condition is a transient outage they should retry (e.g. BadNoCommunication / BadServerNotConnected / BadCommunicationError, whichever matches the existing driver comms-loss contract).

Where: the generic exception handler on the raw and modified-read paths in OtOpcUaNodeManager maps any backend exception to BadHistoryOperationUnsupported. Check the AtTime / Processed / Events paths too.

Fix sketch:

Classify backend failures as transport/unavailable (RpcException Unavailable/DeadlineExceeded, SqlException connection errors, socket errors) versus genuinely unsupported.
Map transport/unavailable failures to a communication status.
Keep BadHistoryOperationUnsupported for real unsupported cases.
Test with each backend's fake throwing its real transport exception.

Check ScadaBridge's handling of history status codes before changing — consumer impact.

Evidence: scratchpad g692/l692-vpn-drop-0600Z.log.

Found by the #692–#694 live AVEVA gate (2026-10-13). A ~2 minute VPN drop hit one run. Pre-existing; affects every historian backend. Low/medium. **Symptom:** while the backend (here the HistorianGateway → AVEVA path) is unreachable, HistoryRead Raw/Modified answers `BadHistoryOperationUnsupported`. That tells clients the node has no history at all and they should stop asking. The real condition is a transient outage they should retry (e.g. `BadNoCommunication` / `BadServerNotConnected` / `BadCommunicationError`, whichever matches the existing driver comms-loss contract). **Where:** the generic exception handler on the raw and modified-read paths in `OtOpcUaNodeManager` maps any backend exception to `BadHistoryOperationUnsupported`. Check the AtTime / Processed / Events paths too. **Fix sketch:** - Classify backend failures as transport/unavailable (`RpcException` Unavailable/DeadlineExceeded, `SqlException` connection errors, socket errors) versus genuinely unsupported. - Map transport/unavailable failures to a communication status. - Keep `BadHistoryOperationUnsupported` for real unsupported cases. - Test with each backend's fake throwing its real transport exception. Check ScadaBridge's handling of history status codes before changing — consumer impact. Evidence: scratchpad `g692/l692-vpn-drop-0600Z.log`.

dohertj2 referenced this issue

2026-10-13 02:12:14 -04:00

HistoryRead-Raw with NumValuesPerNode=1 returns an empty page between every value #692

dohertj2 referenced this issue

2026-10-13 02:12:15 -04:00

Gateway historian: strict lowered ceiling refuses ordinary pages; deep event reads slow (follow-ups from #689–#691 gate) #694

dohertj2 referenced this issue

2026-10-13 03:51:22 -04:00

Fix historian missing-tag latency, paging limits and response contracts #699

dohertj2 commented

2026-10-13 03:52:23 -04:00

Implemented actual transport-outage classification across Raw, Modified, Processed, AtTime and Events: BadNoCommunication. Gateway package/nested gRPC outages and SQL Server/QuestDB connection failures are wrapped consistently at the backend boundary. Unsupported operations retain BadHistoryOperationUnsupported; server cancellation retains BadTimeout. Tests check SDK service/result statuses, nested gRPC errors and repeated real refused database connections. ScadaBridge source/tests contain no HistoryRead consumer. Ready in the pushed branch; this issue closes when PR #699 merges.

Pushed commit 97668d26; PR: #699.

Full solution verified: 14,581 passed, 609 skipped, 0 failed across 62 suites (dotnet test ZB.MOM.WW.OtOpcUa.slnx --verbosity quiet, exit 0). Independent final review found no important defects. New fixes have not been deployed or live-tested end to end through OPC UA.

Implemented actual transport-outage classification across Raw, Modified, Processed, AtTime and Events: BadNoCommunication. Gateway package/nested gRPC outages and SQL Server/QuestDB connection failures are wrapped consistently at the backend boundary. Unsupported operations retain BadHistoryOperationUnsupported; server cancellation retains BadTimeout. Tests check SDK service/result statuses, nested gRPC errors and repeated real refused database connections. ScadaBridge source/tests contain no HistoryRead consumer. Ready in the pushed branch; this issue closes when PR #699 merges. Pushed commit `97668d26`; PR: https://gitea.dohertylan.com/dohertj2/lmxopcua/pulls/699. Full solution verified: 14,581 passed, 609 skipped, 0 failed across 62 suites (`dotnet test ZB.MOM.WW.OtOpcUa.slnx --verbosity quiet`, exit 0). Independent final review found no important defects. New fixes have not been deployed or live-tested end to end through OPC UA.

dohertj2 closed this issue

2026-10-13 03:53:43 -04:00

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Reference: dohertj2/lmxopcua#697