Prerequisite for OtOpcUa Warm redundancy (lmxopcua#717): a Warm standby keeps a
healthy session but serves BadOutOfService at a standby ServiceLevel (90/50, boot 1),
so a connection that lands there sat on Bad quality forever.
- OPC UA connections with a backup poll Server_ServiceLevel (i=2267) on the connected
endpoint (IServiceLevelReadable, implemented by OpcUaDataConnection; never raises
Disconnected). A level < 200 sustained for the degraded window (default 10 s), or
the first sample after any (re)connect, triggers a probe of the other endpoint
(short-lived session: connect, read, dispose). Switch only when it reports a
Healthy (>= 200) higher level, and not within the minimum dwell (default 60 s) of
the previous ServiceLevel switch. Both degraded, other unreachable or level
unknown: stay put. 250/240 (today's OtOpcUa) never starts a streak.
- The switch reuses the failover path: SwitchToOtherEndpoint() now shared by all
three triggers, then BecomeReconnecting(ReconnectCause.ServiceLevelFailover) -
zero delay, no unstable accounting, ReSubscribeAll on the new endpoint.
- Config: OpcUaEndpointConfig.ServiceLevelFailover {enabled, degradedWindowSeconds,
minDwellSeconds}, read from the PRIMARY endpoint's JSON only; null = defaults
(enabled, 10, 60). Inside the encrypted protocol JSON, so no schema change or
migration. Central UI: fields in the Backup card next to Failover Retry Count.
Global: ScadaBridge:DataConnection:ServiceLevelPollInterval (2 s) and
ServiceLevelProbeTimeout (15 s).
- Tests: actor tests per trigger/non-trigger with positive controls, an unsolicited
promotion RefreshStart/RefreshEnd test at client and actor level, adapter tests,
and a real in-process OPC UA server pair end to end. All 15 mutants killed.
- Docs: Component-DataConnectionLayer, components/DataConnectionLayer, Component-CLI.
Claude-Session: https://claude.ai/code/session_01GT67ACmpMR7b9LGRPLijMi
Comment/XML-doc changes only:
- add summaries to ~10k test methods, fixtures, fakes and helpers
(+ <param> on theories, <returns> on async Task methods,
<inheritdoc/> on interface implementations the checker can resolve)
- strip ~2.6k project-tracking references (WP*, P*-*, row-NN, Task N,
#NN, Component-0NN) from comments, keeping the explanatory text;
reword false positives in comments only
- real docs on fakes implementing BCL/library interfaces
(IDisposable, ILogger, IOptionsMonitor, IAsyncLifetime)
- reword the last 5 src/ false positives (CWE-1236, failures-1,
year-0001, M365)
Only non-comment edits: four one-line nested classes split across lines
so members can carry docs. Build 0 errors / 0 warnings.
Joseph Doherty