ScadaBridge/docs/plans/2026-07-23-otopcua-v3-raw-path-live-gate.md

OtOpcUa v3 raw-path live-gate (Gitea #14) — PASS

Date: 2026-07-23 · Scope: the raw-subtree slice of #14 (decision: "raw gate now, flag B/C"). Rig: ScadaBridge docker rig (scadabridge:latest, rebuilt with the host-rewrite fix) against the live otopcua-dev v3 cluster (otopcua-host:dev, built 2026-07-23, branch feat/mesh-phase5, past the v3 merge ec6598ce). Related: scope doc 2026-07-23-otopcua-v3-dual-namespace-cutover-scope.md, phase-2 plan 2026-07-23-otopcua-v3-nsu-hardening-and-browse-ux.md.

Headline

ScadaBridge is confirmed structurally v3-safe against a real dual-namespace server — durable nsu= references are emitted by browse, stored on bindings, and resolved live against the server's NamespaceArray to Good-quality reads. The gate also surfaced and fixed a real DCL robustness bug (couldn't dial a server advertising 0.0.0.0). Items B/C remain deferred — the dev cluster has no UNS nodes and no native alarms to gate them against.

Environment findings

• v3 cluster publishes both namespaces: ns=2 = https://zb.com/otopcua/raw, ns=3 = https://zb.com/otopcua/uns. Raw lands at ns=2 — the exact index collision scope §4 item A predicted (v2's sole namespace and v3 raw both at ns=2).
• Raw tree is sparsely populated: one materialized live Variable, nsu=https://zb.com/otopcua/raw;s=sa-modbus2/plc/SiteAOnly (Int16, AccessLevel=1 → read-only). Other drivers (calc1, opcua1, pymodbus, gate-modbus, Area1) expose folders but no live leaf tags.
• UNS (ns=3) is empty — ns=3;s=OtOpcUa → BadNodeIdUnknown; no Equipment authored.
• No native alarms — zero HasCondition/HasEventSource refs anywhere in the raw tree.

The fix this gate produced

RealOpcUaClient took the server-advertised EndpointDescription.EndpointUrl verbatim for the session channel. OtOpcUa advertises opc.tcp://0.0.0.0:4840/OtOpcUa (its OpcUaApplicationHostOptions.PublicHostname defaults to 0.0.0.0), and dialling 0.0.0.0 from inside the client container hits its own loopback → connect fails. Added RealOpcUaClient.RewriteEndpointHostForReachability (swaps the advertised authority for the reachable discovery host/port, preserves scheme+path, no-op when already reachable), called in both ConnectAsync and VerifyEndpointAsync. Mirrors CoreClientUtils.SelectEndpoint and OtOpcUa's own client (IEndpointDiscovery). Commit a1abbff7 on fix/opcua-discovery-host-rewrite; 9 unit tests (RealOpcUaClientEndpointRewriteTests).

Wiring (how the gate was run)

1. Rebuilt scadabridge:latest with the fix (bash docker/deploy.sh).
2. docker network connect otopcua-dev_default scadabridge-site-a-a (and -b) — bridged the two docker networks so site-a can resolve otopcua-dev-site-a-1-1.
3. data-connection create --site-id 1 --name OtOpcUa-v3-raw --protocol OpcUa → endpointUrl=opc.tcp://otopcua-dev-site-a-1-1:4840/OtOpcUa, securityMode none (id 3044).
4. deploy artifacts --site-id 1 — pushed the def to site-a's LocalDb + made it live in the DCL.
5. Template 2148 (OtOpcUaV3Probe) + attribute SiteA (Int32, --data-source nsu=https://zb.com/otopcua/raw;s=sa-modbus2/plc/SiteAOnly); instance 98 (otopcua-v3-probe-1) on site-a; set-bindings [["SiteA",3044]]; deploy instance.

Checks

#	Check	Result
1	Connect via ConnectAsync (through the rewrite fix)	PASS — data-connection browse returned the address space
2	Connect via VerifyEndpointAsync (second rewrite call site)	PASS — verify-endpoint → {"success":true}
3	Browse emits durable nsu= throughout	PASS — root nsu=…/raw;s=OtOpcUa, drivers + …;s=sa-modbus2/plc/SiteAOnly
4	Both namespaces visible / discoverable	PASS (partial) — raw browsable; uns registered but empty (nothing to browse)
5	Durable nsu= binding resolves live	PASS — attribute stores nsu=…, subscription resolves it against the live NamespaceArray
6	Read round-trip, Good quality, live	PASS — SiteA Good, values changing 59689→59806→59822→59834 across snapshots
7	Write round-trip	N/A — the only materialized tag is read-only (AccessLevel=1); no writable v3 tag to gate

Deferred (unchanged — need OtOpcUa-side authoring on the dev cluster)

• Item A — re-author legacy ns=2 bindings to nsu= (data; the collision is confirmed real here).
• Item B — native-alarm dedup across raw+uns fan-out: no native alarms exist to drive it.
• Item C — UNS-bound → RawPath alarm routing: no UNS nodes and no alarms exist to drive it.

To gate B/C, the OtOpcUa dev cluster needs UNS Equipment authored (populate ns=3, referencing raw tags) and at least one alarm-configured tag raising a Part-9 condition that fans to raw + equipment notifiers.

Rig artifacts created (non-default rig state)

• ScadaBridge site-a-a / site-a-b attached to otopcua-dev_default (dropped on next docker/deploy.sh).
• Site-a config: DataConnection 3044 OtOpcUa-v3-raw, template 2148, instance 98 (deployed). Harmless; remove with instance delete 98 / template delete 2148 / data-connection delete 3044 if a clean rig is wanted.