0001cdd579
Core.ScriptedAlarms-009 resolution: replace the per-call Dictionary +
AlarmPredicateContext allocation with a per-alarm reusable AlarmScratch
held in _scratchByAlarmId, refilled in place under _evalGate on each
evaluation. The hot path no longer allocates per upstream tag change.
Why this matters:
On a busy line where many tags feeding many alarms change frequently,
the old BuildReadCache allocated a fresh dictionary + context on every
predicate evaluation — a steady stream of short-lived allocations the
GC eventually has to reclaim. With the reuse, the dictionary and
context are allocated once per alarm (on first evaluation) and refilled
in place across every subsequent re-eval.
Implementation:
- New private AlarmScratch class holds the reusable
Dictionary<string, DataValueSnapshot> read cache (pre-sized to the
alarm's Inputs.Count) and the AlarmPredicateContext that wraps it by
reference. The context observes refilled values without being
re-created.
- ConcurrentDictionary<string, AlarmScratch> _scratchByAlarmId on the
engine, cleared in LoadAsync alongside _alarms so a config-publish
drops the prior generation's scratch (Inputs / Logger may change).
- EvaluatePredicateToStateAsync looks up scratch via GetOrAdd, calls
the new RefillReadCache(Dictionary, IReadOnlySet) helper to clear +
repopulate the dictionary in place, then runs the predicate against
the reused context.
- BuildReadCache removed.
Safety:
Reuse is serialised under _evalGate which guarantees no two threads
ever observe the same scratch in a half-refilled state. The
AlarmPredicateContext is bound to the scratch dictionary by reference,
so the predicate's ctx.GetTag(path) sees the freshly-refilled values
rather than a stale snapshot.
Verification:
- All 66 ScriptedAlarms tests pass (was 63 — three new regression tests
locking the reuse contract).
- All 56 VirtualTags tests still pass (unchanged).
- All 104 Core.Scripting tests still pass (unchanged).
New tests in ScriptedAlarmEngineTests:
- Reevaluation_reuses_the_same_read_cache_dictionary — asserts
ReferenceEquals(scratch_before, scratch_after) across two
evaluations of the same alarm.
- Reevaluation_reuses_the_same_predicate_context — same, for the
context.
- LoadAsync_drops_the_prior_generations_scratch — asserts a config
publish wipes the prior scratch (so a stale Logger / Inputs can't
leak into the new generation).
Internal test hooks TryGetScratchReadCacheForTest /
TryGetScratchContextForTest added via the existing
InternalsVisibleTo for the tests project. Kept internal — not part of
the public engine surface.
Docs:
- docs/v2/Galaxy.Performance.md "Scripted-alarm engine" section
rewritten as "hot-path allocation reuse" documenting the new
contract + reuse safety reasoning + the three regression tests.
- code-reviews/Core.ScriptedAlarms/findings.md -009 flipped
Won't Fix → Resolved.
- code-reviews/README.md regenerated.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
OtOpcUa
OPC UA server (.NET 10 AnyCPU) that exposes a fleet of industrial drivers as a single OPC UA address space. Drivers ship in-process for AVEVA System Platform Galaxy (via the sibling mxaccessgw repo), Modbus TCP, Siemens S7, Allen-Bradley CIP (ControlLogix / CompactLogix), Allen-Bradley Legacy (SLC 500 / MicroLogix), Beckhoff TwinCAT (ADS), FANUC FOCAS, and OPC UA Client (gateway).
A cross-platform client stack (.NET 10) — shared library, CLI, and Avalonia desktop app — connects to any OPC UA server.
Architecture
OPC UA Clients (CLI, Desktop UI, 3rd-party)
|
v
+-------------------------------------+
| OtOpcUa.Server (.NET 10 AnyCPU) |
| address space + capability fan-out|
+-------------------------------------+
| | | | | | | |
Galaxy Modbus S7 AbCip AbLeg TwinCAT FOCAS OpcUaClient
|
v
mxaccessgw (sibling repo, gRPC)
|
v
MXAccess COM (x86 worker, on AVEVA box)
Galaxy is the only driver with an external runtime: it speaks gRPC to a separately installed mxaccessgw server (sibling repo at c:\Users\dohertj2\Desktop\mxaccessgw\) which owns the MXAccess COM apartment and the x86/STA bitness constraint server-side. Everything in this repo is platform-agnostic .NET 10.
Prerequisites
- .NET 10 SDK (server, drivers, clients all target .NET 10)
- SQL Server reachable for the central config DB
- For Galaxy specifically: a running
mxaccessgwdeployment — see docs/v2/Galaxy.ParityRig.md - For Wonderware Historian read-back: optional
OtOpcUaWonderwareHistoriansidecar — see docs/ServiceHosting.md
Quick Start
dotnet restore ZB.MOM.WW.OtOpcUa.slnx
dotnet build ZB.MOM.WW.OtOpcUa.slnx
dotnet test ZB.MOM.WW.OtOpcUa.slnx
# Run the server in dev (foreground)
dotnet run --project src/Server/ZB.MOM.WW.OtOpcUa.Server
The server starts on opc.tcp://localhost:4840 with the None security profile. Configure Security.Profiles in src/Server/ZB.MOM.WW.OtOpcUa.Server/appsettings.json to enable Basic256Sha256-Sign or Basic256Sha256-SignAndEncrypt. See docs/security.md.
Install as Windows Services
Production deployment is driven by scripts/install/Install-Services.ps1, which registers the OtOpcUa server service (and optionally the OtOpcUaWonderwareHistorian sidecar) under a chosen service account. Galaxy support requires a separately installed mxaccessgw — neither this repo nor the install script provisions it.
.\scripts\install\Install-Services.ps1 `
-InstallRoot 'C:\Program Files\OtOpcUa' `
-ServiceAccount 'DOMAIN\svc-otopcua'
Add -InstallWonderwareHistorian for the historian sidecar. See the script header and docs/ServiceHosting.md for full options.
Client CLI
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- connect -u opc.tcp://localhost:4840
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- browse -u opc.tcp://localhost:4840 -r -d 3
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- read -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode"
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- write -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode" -v 42
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- subscribe -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode" -i 500
See docs/Client.CLI.md and docs/Client.UI.md.
Documentation
Architecture deep-dives
| Topic | Doc |
|---|---|
| OPC UA server composition, namespace fan-out, Polly invoker | docs/OpcUaServer.md |
| Address space layout | docs/AddressSpace.md |
| Read / Write dispatch (driver vs virtual vs scripted-alarm) | docs/ReadWriteOperations.md |
| Incremental sync (driver-backend rediscovery + config publishes) | docs/IncrementalSync.md |
| Service hosting (Server + Admin + optional historian sidecar) | docs/ServiceHosting.md |
| Security (transport, LDAP, certificates) | docs/security.md |
| Redundancy | docs/Redundancy.md |
| Status dashboard | docs/StatusDashboard.md |
Drivers
| Topic | Doc |
|---|---|
| Driver specs (per-driver capability surface, config, addressing) | docs/v2/driver-specs.md |
| Galaxy driver | docs/drivers/Galaxy.md |
| Modbus / S7 / AbCip / AbLegacy / TwinCAT / FOCAS / OpcUaClient | docs/drivers/ |
| Galaxy parity rig (mxaccessgw setup) | docs/v2/Galaxy.ParityRig.md |
| Galaxy performance + tracing | docs/v2/Galaxy.Performance.md |
Clients
| Topic | Doc |
|---|---|
| Client CLI | docs/Client.CLI.md |
| Client UI (Avalonia desktop) | docs/Client.UI.md |
v1 archive
The original v1 in-process MXAccess docs (Galaxy.Host topology, Configuration env vars, AlarmTracking, DataTypeMapping, HistoricalDataAccess, Subscriptions, etc.) are preserved under docs/v1/ — historical reference only. PR 7.2 retired the v1 architecture on 2026-04-30; current state is documented in the sections above.
License
Internal use only.