MaterialiseAlarmCondition never assigned the three mandatory BaseEventType
identity fields, so all three arrived null on every condition event — native
and scripted. The SDK does not synthesise them on this path: Create() builds
the children from the type definition but leaves them unset, the auto-filling
BaseEventState.Initialize overload is only used for transient events, and
ReportEvent / InstanceStateSnapshot copy children verbatim. A conforming
client could not attribute an alarm to its source.
EventType = the concrete materialised type (TypeDefinitionId)
SourceNode = the condition's own NodeId (== ConditionId) — the condition IS
the source; an alarm-bearing raw tag materialises only the
condition, with no sibling value variable
SourceName = the same identifying id string: RawPath (native) /
ScriptedAlarmId (scripted)
SourceName carries the unique id rather than the leaf name: the leaf collides
across devices (HR200 on two PLCs) and is already carried by ConditionName, so
nothing is lost. Documented in docs/AlarmTracking.md, including that clients
must key on ConditionId and must not compose SourceName with ConditionName,
and that SourceName is NOT a live<->history join key (the alarm-history writer
stamps it with the EquipmentPath — a pre-existing divergence, now called out).
Tests: NativeAlarmEventIdentityFieldDeliveryTests is the wire-level guard —
a real client subscription using the standard [EventType, SourceNode,
SourceName, Time, Message, Severity] select clause, verified to fail against
the pre-fix server. NodeManagerAlarmSourceFieldsTests guards the node across
both realms, the base-type fallback, and the kind-swap re-materialise.
The HistoryRead events projection is a separate path (it projects historian
rows, not node fields) and is unaffected — its EventType => Variant.Null
assertions still hold.
Joseph Doherty
7339a4af07