Joseph Doherty
dfbcb0e7f0
C1 (critical): a latched "this endpoint cannot stream" verdict could end with a GREEN driver holding a permanently silent subscription. DriverInstanceActor handles a tag-set change as Unsubscribe-then-Subscribe with no re-initialize; the unsubscribe cleared the stream-degraded flag, the resubscribe was refused by the latch without a word, and one successful read then reported Healthy. StartSampleStreamCore now re-asserts the degradation and logs a Warning naming the remedy, and teardown no longer clears the flag while the latch is set. NOT promoted to Faulted: DriverHealthReport maps any Faulted driver to a /readyz 503, so that would de-ready the whole node over one misconfigured Agent whose reads are perfectly healthy. Faulted stays for the case that earns it. I1: teardown waits are bounded (5 s) and honour the caller's token. They were unbounded and ignored it, so DriverInstanceActor's 5 s budget was inert and PostStop — which blocks a dispatcher thread on ShutdownAsync while holding the lifecycle semaphore — could be wedged forever by one blocking subscriber. The cancellation source is disposed only when the loop is provably gone. Applied to StopProbeLoopAsync too: Task 13 reproduced the identical shape, and closing the class in one method while leaving the other as the pattern to copy is worse than not closing it. I2: the reconnect ladder was monotonic for the process lifetime, so ~9 unrelated drops pinned the driver at MaxBackoffMs forever. A stream that delivered before dropping now starts a fresh ladder (at attempt 1, not 0, so MinBackoffMs is still honoured). I3: MaxBackoffMs <= 0 clamped every delay to zero — an operator-authorable reconnect spin. Treated as unset, like a multiplier that cannot grow. I4: the session published instanceId without NextSequence, so after a restart it held the new agent's id beside the dead one's cursor, and a gap/OUT_OF_RANGE re-baseline (id unchanged) never published the cursor at all. Both move in one CAS, and the pump publishes its cursor as it exits. I5: OnDataChange was a multicast Invoke — the first throwing handler aborted the rest of the list, starving every later subscriber. Now walked by hand with the catch inside the loop. The test that claimed to cover this registered the recorder BEFORE the thrower, so it passed regardless; swapped, it was red. Faults are latched to one Warning per stream generation (Debug thereafter) so a consistently-throwing consumer cannot flood the log. Also: the pump restarts after an unexpected fault (IsCompleted, not null); a device-scope that matches nothing is a Warning, not a Debug tally; a device or component with neither name nor id is skipped rather than emitting a blank path segment; DiscoverAsync's remark no longer claims DriverInstanceActor retries (it does not for a Once driver, and injection is dormant in v3); and two flake seeds in the fake are gone (Dispose re-read its own counter; _disposeCts was disposed under a racing SampleAsync). 439/439. Every changed behaviour falsified by mutation.
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, OPC UA Client (gateway), and MQTT (broker subscribe; Sparkplug B in progress).
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 MQTT
|
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 historian read-back / alarm history / continuous historization: a running
ZB.MOM.WW.HistorianGatewaydeployment (the sole historian backend; consumed as theZB.MOM.WW.HistorianGateway.ClientgRPC package). It must runRuntimeDb:Enabled=true+RuntimeDb:EventReadsEnabled=true, and the API key must carryhistorian:read+historian:write+historian:tags:writescopes.
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.Host
The server starts on opc.tcp://localhost:4840 with the None security profile. Configure Security.Profiles in src/Server/ZB.MOM.WW.OtOpcUa.Host/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 under a chosen service account. Historian support requires a separately deployed ZB.MOM.WW.HistorianGateway and Galaxy support a separately installed mxaccessgw — neither this repo nor the install script provisions them.
.\scripts\install\Install-Services.ps1 `
-InstallRoot 'C:\Program Files\OtOpcUa' `
-ServiceAccount 'DOMAIN\svc-otopcua'
The historian backend is the external ZB.MOM.WW.HistorianGateway (not installed by this script). 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; external HistorianGateway backend) | 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 / MQTT | 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.