Extended AlarmClientWmProbeTests.ProbeAlarmClientWmMessages to also
call GetStatistics every ~2s during the pump window. Re-ran on the
dev rig 2026-05-01:
- GetStatistics is safely callable from the same thread that did
RegisterConsumer + Subscribe. Every poll (9 calls / 20s window)
returned rc=0, no exceptions.
- Galaxy currently has zero active alarms. total=0 active=0
suppressed=0 newAlarms=0 across every poll. positions[] and
handles[] arrays were empty.
- changes=1 codes=[7] was constant across all polls, matching the
constant 1 Hz WM 0xC275 cadence — same heartbeat semantics
exposed through both the WM path and the pull API.
Confirms the polling design is mechanically viable: GetStatistics
threading-affinity is fine and the call is cheap. The remaining
unknown is whether GetStatistics populates positions[] / handles[]
with real entries when an alarm actually fires. Proving that
requires triggering an alarm — next probe is an MxAccess write to a
$Alarm-extended boolean tag (reference pending).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Added MxGateway.Worker.Tests/AlarmClientWmProbeTests.cs as a Skip-gated
runtime probe. Run on the dev rig 2026-05-01 against the live AVEVA
install (Galaxy reachable, no manual alarm fired). Findings:
- RegisterConsumer(hWnd, ...) and Subscribe("\Galaxy!", ...) both
return 0 (success). Calls are valid against the deployed assembly.
- A registered-message-class WM (ID 0xC275 in this OS session) fires
every ~1 second after Subscribe completes. Constant wParam=0x1100,
constant lParam=0x079E46D8 — looks like a heartbeat / keepalive,
not a per-change notification.
- Critically, this WM is delivered to AVEVA's own internal window
(hwnd=0x18032E), NOT to the consumer hWnd we registered. The
consumer window receives only the standard WM_CREATE / WM_DESTROY
sequence; no AVEVA traffic in between.
This invalidates the WM_APP-pump design previously documented. The
hWnd parameter to RegisterConsumer appears to be a registration
identity only — AVEVA's notification path runs entirely against
AVEVA's own internal window.
Two viable A.2 designs replace the previous one:
1. Polling. Call GetStatistics on a 500ms timer in the worker's STA
and react to whatever change set it reports. No window plumbing
needed. Latency floor = poll period. Matches AVEVA's own
internal heartbeat cadence.
2. Hook AVEVA's internal window. Discover AVEVA's own hwnd,
SetWindowSubclass on it, intercept WM 0xC275 on AVEVA's thread.
Higher fidelity, lower latency, but invasive and fragile across
AVEVA upgrades — likely a non-starter.
Recommendation in docs/AlarmClientDiscovery.md is option 1 (polling)
unless a follow-up probe with a real fired alarm shows AVEVA does
post change-specific WMs to a different hWnd.
Open follow-up probes documented:
- Fire a real Galaxy alarm during pump and check whether WM 0xC275
cadence changes or GetStatistics returns non-empty arrays.
- GetStatistics threading affinity test.
- Hook AVEVA's internal window 0x18032E.
- Decompile aaAlarmManagedClient IL for RegisterConsumer to find
whether WNAL_Register's callback surface is wrapped.
Test project changes:
- Added Reference to aaAlarmManagedClient + IAlarmMgrDataProvider
(Private=true so the DLL gets copied into bin for test load).
- Test-suite-wide: 127 real tests still pass; both alarm-related
Skip-gated tests skip cleanly.
Code change to the probe is additive — the worker is unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Reflection probe of the deployed aaAlarmManagedClient.dll
(v1.0.7368.41290) on 2026-05-01 confirmed the public AlarmClient class
exposes zero public events. The PR A.5 design that AlarmClientConsumer
is built on (managed-event surface, no message pump) does not hold
against this assembly.
The actual notification mechanism is WM_APP messaging:
RegisterConsumer(hWnd, ...) takes a window handle because AVEVA's alarm
provider WM_APP-pokes the registered window, then GetStatistics +
GetAlarmExtendedRec pull the change set on each poke.
Practical impact:
- AlarmClientConsumer.AlarmRecordReceived has no production caller.
RaiseAlarmRecordReceived is invoked only from tests. Subscribe(...)
returns OK from RegisterConsumer + Subscribe but no notifications
reach the consumer at runtime because no window is attached.
- Until A.2 lands a hidden message-only window + WindowProc that routes
WM_APP into MxAccessAlarmEventSink.EnqueueTransition, the gateway's
MX_EVENT_FAMILY_ON_ALARM_TRANSITION family cannot carry events.
- AcknowledgeByGuid and SnapshotActiveAlarms are pull-style and remain
correct as written.
Changes:
- docs/AlarmClientDiscovery.md (new) — reflection probe summary, full
AlarmClient method list, open questions for A.2 implementation.
- AlarmClientConsumer.cs xmldoc — replaced the inaccurate "managed
event surface" claim with the WM_APP finding; flagged
AlarmRecordReceived as unreachable in production until the WM_APP
pump lands.
- MxAccessAlarmEventSink.cs xmldoc — replaced the "verify on dev rig"
hedge in the wiring plan with the resolved finding; expanded the
open-questions list (WM_APP message ID, wParam/lParam semantics, STA
affinity, subscription scope) so the next A.2 PR knows what the
dev-rig probe needs to answer.
Code-only no-op for the worker; worker builds clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty