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Marc Schier
f5ad124891
# Description
Brings the stack's fuzz testing to parity with the fork
(`aio-opcua-sdk`), then fixes every defect the resulting campaigns
exposed.
The fork's fuzzing was used as the behavioural baseline: all **28
fork-local callbacks** and **13 OneFuzz registrations** are now
accounted for by an explicit mapping, not just by a larger target count.
The work extends the existing SharpFuzz/NUnit infrastructure rather than
introducing another framework.
### Coverage
- **84 continuous libFuzzer targets** and **81 AFL adapters** across
Encoders, Certificates, Network and PubSub.
- **PubSub area integrated** (Corpus/Tools/Tests siblings, solution
entries) — it previously had host source only and was absent from the
solution and replay infrastructure.
- Segmented binary adapters, binary-to-JSON and XML-to-JSON conversions,
standalone certificate loading, both chain-parser variants, CRL encoding
and canonical TBS round-trips.
- The 12 original fork message inputs are retained byte-identically
alongside richer deterministic generators; the three historical
crash/slow/timeout reproducers are unchanged (verified identical by
SHA-256).
### Production fixes found by fuzzing
These are real robustness and data-integrity bugs, each with a retained
regression input:
- `UadpBinaryReader.Advance` accepted attacker-controlled lengths on the
receive path. Declared payload sizes are now authoritative bounded
sections, with negative-count rejection and overflow-safe reassembly
arithmetic.
- PubSub JSON decoding leaked `InvalidOperationException` for invalid
UTF-8.
- `JsonEncoder.WriteExtensionObject` leaked
`System.Text.Json.JsonReaderException`.
- `JsonEncoder` silently emitted a lossy `{}` for an `ExtensionObject`
whose TypeId could not be represented in JSON.
- `JsonDecoder` wrapped a bodyless `ExtensionObject` envelope as a raw
JSON body instead of preserving `ExtensionObjectEncoding.None`.
- `Node.Encode` lost the null/empty collection distinction.
- Binary/XML Variant matrix dimensions are prevalidated rather than
relying on a caught `ArgumentException`.
- `X509CRL.ReadTime` pre-validates strict RFC 5280 whole-second Zulu
time forms.
- `Utils.ParseCertificateChainBlob` disposes correctly on partial-chain
failure.
- **`nodeid.dict` was unloadable by libFuzzer** (empty token, unescaped
quote). libFuzzer rejects the whole file on one bad line, so four parser
targets silently executed **zero** inputs. Fixed and now guarded by
dictionary validation.
### Infrastructure
- `fuzzing/fuzz-targets.json` manifest recording adapters, corpora,
dictionaries, oracles and fork-behaviour mappings, with
`validate-fuzz-manifest.ps1` and **27 negative controls**.
- Strict host/tools discovery and replay: `--list`, `--replay`, non-zero
exits on unknown targets, missing or empty corpora, and failed callbacks
(playback previously logged failures and returned success).
- A real process watchdog for the timeout/slow regressions — NUnit
`CancelAfter` cannot interrupt a synchronous fuzz callback.
- Runner scripts made non-destructive (unique work directories, no
generic `bin`/findings deletion) and corrected to the native driver's
single-`--target_arg` apphost contract.
- Opt-in `OneFuzz=true` class-library publication producing a
relocatable, **uninstrumented** drop, validated by exact callback
discovery, dependency closure, corpora and dictionaries.
- CI: fuzz replay matrix plus a public drop gate, triggered by corpus-,
dictionary- and script-only changes.
### Verification
| Gate | Result |
|---|---|
| Bounded campaigns, all 84 targets (1,000 inputs, seed 1) | 84/84,
84,000 executions, zero findings |
| OneFuzz drop | 84/84 published callbacks replayed, zero skips |
| Fuzz replay net10.0 / net8.0 / net9.0 | 9,470 passed each, 0 failed |
| Fuzz replay net48 | 8,996 passed, 0 failed (Network/PubSub are
modern-only) |
| `Opc.Ua.Types.Tests` / `Opc.Ua.Core.Tests` | 9,800 and 4,442 passed, 0
failed |
| Retained regression assets | 132 `crash-*` inputs replayed by every
target each run |
### Known gaps (deliberately not closed)
- **Fidelity is not enforced against the pipeline crash corpus.** The
differential binary-to-JSON targets assert both robustness (no unhandled
exception, expected of arbitrary bytes) and fidelity (a decoded value
re-encodes equivalently, a property of well formed values). The pipeline
supplies 22,293 blobs collected for the targets that existed before this
PR, none of which asserted fidelity; 522 of them violate it, and that
count did not move across two rounds of genuine fixes because each fix
only lets the mutator reach the next representability gap. Rather than
weaken the assertion, the two contracts are separated: fidelity failures
raise `EncodingFidelityException`; curated assets under `Assets/Repo`,
the curated `Testcases` corpus and every continuous libFuzzer campaign
stay strictly enforced, while externally supplied assets are gated on
robustness only and their fidelity findings are reported with counts and
bounded base64 reproducers.
- **Internal MSFT OneFuzz canary has not been run.** It needs an
owner-supplied ownership profile, pipeline authorisation and corpus
snapshot; none were available. The drop builds and validates locally and
records `serviceCanaryPerformed: false`. A build or upload is not a
successful worker run.
- **Legacy JSON wire forms are a partial mapping.** The fork accepts its
four original `TypeId`/`Body` messages; this stack rejects that retired
envelope (measured JSON-only control: fork `JsonEncoder` 630/1356 lines
vs 0/1007 here). Recorded as an explicit unresolved mapping rather than
an exemption. `LegacyNonReversible` is a RawData-derived profile and is
not counted as independent coverage.
## Related Issues
_No tracking issue was supplied for this work; happy to open one and
link it if maintainers prefer._
- Fixes #github-issue-number, ...
## Checklist
- [ ] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [x] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [x] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [x] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed.
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.
> Note on the checklist: the fuzz replay matrix, `Opc.Ua.Types.Tests`
and `Opc.Ua.Core.Tests` were run locally on **net48** and **net10.0**
(plus net8.0/net9.0) and all passed. CI and CodeQL results are not yet
available for this branch, so those boxes are left unchecked. The CLA
box is for the author to confirm.
OPC UA .NET Standard stack documentation
Here is a list of available documentation for different topics:
New contributor? Start with the Developer Guide — prerequisites, building, testing, coding standards, and how-to recipes (including how to add logging).
- Sample applications - Platform-independent reference, PubSub, minimal API, companion-model, robotics, Vision, AI, ISA-95, and OpenUSD demos included in this repository.
UA Core stack related
- OPC UA Profiles and Facets - Overview of supported OPC UA profiles, facets, security policies, and transport protocols.
- Transport Profiles - Developer guide for the wire transports:
opc.tcp/ HTTPS (binary + JSON + REST) / WSS (binary + JSON), including server hosting and client connect examples. - REST Binding (OpenAPI Mapping) - OPC UA Part 6 §G.3 OpenAPI mapping: ASP.NET Core MVC controllers for every spec service, Compact / Verbose encoding negotiation, four pluggable auth modes (Anonymous / Bearer JWT / HTTP Basic / Mutual TLS), and the symmetric
IWebApiClient. - What's New in 2.0 - Developer-facing tour of the 1.5.378 → 2.0 changes, grouped by theme and layer, with links to deeper feature docs.
- Migration Guide - How to migrate from a previous version.
- Sessions, Reconnection, and Subscription Engines - Architectural overview of
Session,ManagedSession,SessionReconnectHandler, and the classic / V2 subscription engines, including guidance on which to use. - About .NET platform support, NuGet packages and versioning.
- About continuous integration — which pipeline runs what, how to start a validation build on a pull request with
/azp run, and the coverage gates a change has to satisfy. - How X.509 Certificates are used in the certificate stores.
- CertificateManager - Centralized certificate lifecycle management, server-side push certificate rotation, and the OPC UA Part 12 PushManagement transaction model (
ApplyChanges/CancelChanges, staged TrustList/Certificate updates,DeleteCertificate, pending-key persistence). - Crypto provider - Replacing the stack's cryptography with another library, a remote service or hardware (TPM, HSM, PKCS#11, cloud key service), keeping private keys inside the device, selecting providers per purpose and security policy, and auditing the use of uncertified cryptography.
- Using the Reverse Connect for the UA-TCP and WSS transports.
- Support for the TransferSubscriptions service set.
- Diagnostics — logging, telemetry, server audit events, server diagnostics nodes, and packet capture.
- Performance Benchmarks — BenchmarkDotNet methodology, the 2.0 (
master) vs 1.5.378 (master378) comparison, root-cause analysis of the encoder/decoder/session regressions and their real-world impact, the subscription-notification (pooled encodeable) micro-benchmarks, server session scalability (the 500-session capability, sizing and bottlenecks), and planned future work. - Server Session Scalability — why a single node tops out at ~2000 concurrent sessions, the establishment vs steady-state boundaries (socket backlog, the
BadTcpInternalErrorretry-storm amplifier, the O(N²) diagnostics rescan, CreateSession crypto-under-lock, the RSA CPU wall, and the held-Publish worker-accounting coupling) with code references, and a prioritized admission-control / rate-limiting roadmap for moving beyond it. - Rate Limiting and Admission Control — the server's deterministic, configurable connection- and session-establishment limiters (on by default,
System.Threading.RateLimiting-based, DI-pluggable), theBadServerTooBusysignalling, the diagnostics-independent server retry-after carriers (ResponseHeader.additionalHeader, HTTPRetry-After, UA-TCP ERR, and load-basedServer.ServiceLevel), and the client's server-signal-aware adaptive reconnect backoff (IReconnectPolicy.TryGetNextDelay). - Support for WellKnownRoles & RoleBasedUserManagement.
- Pluggable Identity Providers — interfaces (
IClientIdentityProvider,IUserTokenAuthenticator,IAccessTokenProvider,ITokenIssuer,IIdentityClaims) plus the OPC 10000-6 §6.5.2.2IssuerEndpointUrlJSON parser for OAuth2 / OIDC / Entra / JWT flows. - Support for ECC Certificates.
- Working with ComplexTypes - Custom structures and enumerations.
- Client-based NodeSet Export - Export server address space to NodeSet2 XML.
- Source generated [DataTypes] - How to annotate POCO classes and let the source generator generate the
IEncodeableimplementation. - Runtime Schema Generation - Produce XSD, OPC Binary (BSD) and JSON Schema (Part 6 Annex C, compact + verbose) for generated encodeable types and dynamically added complex types via the injectable
ISchemaProvider; schemas are built as object models in code (trimmable, NativeAOT compatible). - NodeManagers - Overview of the server node-manager architecture, built-in managers (master, core, diagnostics/configuration), CoreNodeManager vs CustomNodeManager2 guidance, registration and runtime lifecycle rules, namespace metadata and historical-access reconciliation, and source-generated
AsyncCustomNodeManagerauthoring with the fluentINodeManagerBuilderAPI. Includes NativeAOT single-file server guidance and samples such as MinimalBoilerServer and PumpDeviceIntegrationServer. - Runtime NodeSets - Load one or more NodeSet2 XML documents into the server address space at startup without source generation. Covers file and stream sources, dependency ordering, parent-child browse-path resolution, fluent
Configurecallbacks, default namespace inference, and the default complex-type loading path. Use when the XML content changes independently of the server binary or for rapid prototyping. - WoT / NodeSet conversion -
WotNodeSetConverterreadable mapping, preservation projections, and the WoT-to-NodeSet default/failure table. - WoT Connectivity - OPC 10100-1 asset connectivity, the WoT Connectivity 1.1 registry/client, dependency-closure materialization, and runtime NodeSet projection.
- WoT protocol bindings - The bindings that ship today (planner/executor architecture, bundled and separate packages, operation coverage, target mapping, lazy channels, generation lifetime) and the contributor guide for adding your own, with a complete memory binding, registration, diagnostics, tests, packaging, TFM, trimming, and NativeAOT guidance.
- WoT aggregation sample - Two flat OPC UA sources aggregated into a runtime-loaded DI/Machinery/Pumps Pump model, including commands, Refresh, monitoring, replacement, troubleshooting, and NativeAOT publishing.
- Device Integration (DI) developer guide - End-to-end documentation for the
Opc.Ua.Di*library trio: fluentIDeviceBuilder, device sub-type extensions (AddSoftware,AddBlock,AddConfigurableObject,AddLifetimeIndication,WithSupportInfo), hosting integration (AddOpcUaDi/ConfigureDevicesFor), lock service, software-update package store, and client helpers (DiLockClient,DiTopologyClient,SoftwareUpdateClient). Includes a section enumerating supported OPC 10000-100 features against the spec. - OpenUSD — bridge an OPC UA address space to an OpenUSD stage, in two parts. Part 1 — bindings: the generic domain-agnostic
OpenUsdConnector(discoversServer/OpenUSD/Representations, subscribes, composes, verifies stage/asset digests, replays history), theVariant-basedIUsdSinkwithUsdFileSink/MockUsdSink, the fluent/DIAddOpenUsdConnectorextensions +OpenUsdConnectorFactory/OpenUsdConnectorOptions, server-sideUsdAssetDelivery, and the optional--viewviewport. Part 2 — scene materialization: materializes a composed USD stage inside the address space so the prim tree is the node hierarchy — theOpc.Ua.OpenUsd.Scenecompanion and scene-document APIs,Opc.Ua.OpenUsd.Scene.Conversion.usdareader/writer and §6.2UsdValueTypeMap(USD roles as DataTypes subtyping their built-in), andOpc.Ua.OpenUsd.Server.Scenematerialization/export APIs with unknown-type fallbacks, Mode-A live attributes, portable Cesium georeference dual-authoring, discovery and Part 1 binding-target resolution. Both parts ship in theOpc.Ua.OpenUsdandOpc.Ua.OpenUsd.Serverpackages, and both companion models are currently drafts. - Robotics developer guide — the
Opc.Ua.Robotics/Opc.Ua.Robotics.Server/Opc.Ua.Robotics.Clienttrio for OPC 40010 Robotics 1.02 over OPC 40001-1 IA and OPC 10000-100 DI: source-generated models,AddRobotics/AddRoboticsModel/ConfigureRobotics(For)hosting,IRoboticsModelProvider/IRoboticsConfigurator/IRoboticsBuildContext, validated fluent topology builders (AddMotionDeviceSystemAsyncdown to axes, power trains, motors, gears, drives, safety states, and task controls), semantic references,ArrayOf<T>snapshot contracts, andRoboticsClientdiscovery. It also covers Robot Intent, the draft task-level motion verbs OPC 40010 leaves undefined, including the MCP surface for LLM agents. - Vision developer guide — the
Opc.Ua.Vision/Opc.Ua.Vision.Server/Opc.Ua.Vision.Client/Opc.Ua.Vision.OpenUsdpackage family for the draft OPC UA — Vision companion specification: source-generated Vision model,AddVision/ConfigureVisionhosting withIVisionMediaProvider/IVisionInferenceProvider/IVisionFeedbackSink, the two perception paths behind one contract (OnServerdeterministic detector vsEdgeOffServeragent submissions), fluent topology builders for frames, sensors, calibrations, media endpoints and inference pipelines,VisionClientdiscovery +VisionFrameGraph§5.12 pose composition +VisionResultReaderstreaming detections +VisionFeedbackClientfor off-server VLM agents, the §6.4 media-gating states, theNoRenderingBackenddegrade path, facet derivation, and the composedvisionMCP profile with the BinPickingCell / BinPickingClient example. - AI Model Management developer guide — the
Opc.Ua.AI/Opc.Ua.AI.Inference/Opc.Ua.AI.Server/Opc.Ua.AI.Clientpackage family for the draft OPC UA — AI Model Management and Inference companion specification over xRegistry: source-generated catalogues, datasets, deployments, inference endpoints and learning jobs, theIInferenceBackendcontract withMicrosoft.Extensions.AIIChatClientand OpenAI-compatible REST backends,AINodeManagerFactoryhosting viaAddNodeManager<AINodeManagerFactory>,Invokerouting, standard file-transfer artefact streaming, credential resolvers that keep secret material out of the address space, and the ModelManagementServer / ModelManagementClient example. - Relative Spatial Location and Global Positioning — source-generated OPC 10000-210 RSL and OPC 10000-211 GPOS models, standalone/composed server hosting, provider contracts, high-level clients, frame-chain resolution, WGS84/ENU conversion, and ground-control-point fitting.
- Generators (generating sets) — the draft Generators companion specification realised end to end by GeneratorServer: a datasheet-driven simulation in which load fraction is the only independent variable, DI + Machinery integration, and one independent OpenUSD twin per configured set. Includes SiteCompositionServer, a supervisory server that owns no devices and composes the pump and generator servers into a single scene through cross-server components.
- ISA-95 developer guide - End-to-end documentation for the
Opc.Ua.ISA95*library trio: the OPC-10030 Common Model and OPC-10031-4 Job Control V1/V2, the two transparently-documented normative NodeSet repairs,AddIsa95Server/AddIsa95Clienthosting, the typed common-model builder, the shared Job Control state engine and itsUncertain/Annex-BReturnStatusresult model, the provider-backedGeoSpatialLocationTypeseam and planned Part 210/211 RSL/GPOS integration, and a conformance matrix distinguishing static NodeSet structure from runtime-tested behavior. - Alias Names - Full server + client support for the OPC UA Part 17 alias-name model (
AliasNameType,AliasNameCategoryType,FindAlias,FindAliasVerbose,AddAliasesToCategory,DeleteAliasesFromCategory,LastChange). - Alarms and Conditions - Full server + client support for OPC UA Part 9. Server-side state types for latched/silenced/out-of-service alarms, alarm groups and suppression engine, alarm rate metrics. Client-side
AlarmClient, typed alarm event records, fluentAlarmEventFilterBuilder,IAsyncEnumerablealarm streaming viaAlarmStreamExtensions. - Historical Access (Part 11) - Server provider model (
IHistorianProviderfamily) andInMemoryHistorianProvider, plus the clientHistoryClient(session.Historian()) for raw/modified/at-time/processed/event reads, modification audit metadata, annotations, and data/event/structured updates. - Aggregates (Part 13) - All 37 standard Part 13 v1.05.07 aggregate functions over historical data: server
AggregateManager/ calculators, native push-down vs framework fallback,AnnotationCountvia the annotation provider,AggregateConfigurationdefaults, and the clientReadProcessedAsynchelper. - Subscriptions and Monitored Items Service Set - V2 subscription engine API. Covers
ISubscriptionManagerfor long-lived callback-based subscriptions, the declarative+imperativeSetTriggeringAPI with N:M support and automatic replay on recreate/reconnect, andIStreamingSubscription(IAsyncEnumerable-based) for state-machine waits and short-lived monitoring (ManagedSession.DefaultStreaming,TakeUntilAsync/WithTimeoutAsynchelpers). - Unbounded Monitored Items - V2 logical-subscription wrapper that transparently splits monitored items across multiple server-side partitions when the per-subscription cap is exceeded (
IPartitionedSubscription,MonitoredItemOptions.Affinity, reactiveBad_TooManyMonitoredItemsfallback, secondary-partition idle-delete). - State Machines - Generic, extensible Part 16 state-machine API. Client side: streaming + read helpers on the source-generated
*TypeClientproxies (GetCurrentFiniteStateAsync,ObserveFiniteTransitionsAsync,WaitForStateAsync). Server side: unified fluentStateMachineBuilderwith two complementary modes — definition (Create(...)+AddState/AddTransition/OnCausefor ad-hoc machines viaFluentFiniteStateMachineState) and lifecycle (For(...)/INodeBuilder.AsStateMachine()+OnEnterState/WithCause/WithTimedTransitionto attach behavior to stack-shipped or generator-emitted FSMs). Vendor state machines inherit both ends of the API automatically. - Model Change Tracking - Client-side address-space change tracking with per-node
INodeCacheinvalidation; server-sideModelChangeAggregatorand auto-emittedGeneralModelChangeEventfromCustomNodeManager.CreateNode/DeleteNode. - NodeManagement Service Set - Server-side AddNodes / DeleteNodes / AddReferences / DeleteReferences, including the
INodeManagementAsyncNodeManageropt-in pattern and per-NodeManagerAllowNodeManagementgate. - High Availability and OPC UA Redundancy - OPC 10000-4 §6.6 mapping for server, client, and network redundancy;
RedundancySupport,ServiceLevel, manual failover, transparent/non-transparentManagedSessionmodes, HotAndMirrored/Transparent state mirroring, distributed address-space/session/subscription stores with CRDT (eventual) or Raft (strong) consistency, shared certificate/trust-list stores, snapshot+delta hydration, and the optional GetEndpoints load-direction seam.- Replica-consistent NodeIds - Required fixed shared namespace layout, guarded factory assignment, protected store/peer contracts, writer-created identities, and unchanged client NodeIds across failover.
- Kubernetes High Availability Deployment - Consolidated Kubernetes guide for the
Opc.Ua.Redundancy.Kubernetespackage: Lease leader election, EndpointSlice peer discovery, ServiceLevel-driven readiness, StatefulSet/Deployment and Service manifests, RBAC, probes, time sync, secrets, and GDS/NTRS registration. - Redundant Sample Integration Tests - Process-level integration tests that launch the
RedundantServer/RedundantClient/RedundantPubSubsample apps and assert on their failover, reconnect, and data-loss-visibility behavior; short-haul variants run on every PR, long-haul soak variants run via dedicated manual/scheduled GitHub Actions and Azure DevOps jobs (SAMPLE_HA_DURATION_MINUTES).
- Dependency Injection - The unified
services.AddOpcUa()/IOpcUaBuildersurface for hosting OPC UA components inMicrosoft.Extensions.DependencyInjection/ the .NET Generic Host (servers asIHostedService, options viaAction<T>orIConfiguration, AOT-friendly). - AuthorizationService - Modern Part 12
StartRequestToken/FinishRequestToken,ITokenIssuer, and GDS token issuance. - Fuzz testing - SharpFuzz + afl-fuzz + libFuzzer integration. Three areas:
Encoders(Binary/JSON/XML decoders, built-in type readers, parser entry points),Certificates(X509CRL, X509 extension parsers,PEMReader,Pkcs10CertificationRequest, ASN.1 helpers), andNetwork(UA-SC framing viaOpc.Ua.Core.Diagnostics+ internalTcpMessageParsersseam onOpc.Ua.Core). Thefuzz-testercustom agent drives the whole toolchain autonomously: it detects OS-available engines, runs them in parallel, fixes novel findings per repo guidelines, adds the failing input as a regression asset, and pushes one commit per fix until the user says stop. - KeyCredentialService - Pull, Push, and experimental bridge guidance for Part 12 KeyCredential flows.
- xRegistry (abstract registry base model) - Generic registry with structural
Xididentity and a separateIResourceContentIdProviderOpaque-NodeId document fast path, true dirty-Closeregistration, federated resource proxies, native events, and resource-exhaustion bounds. Shipped asOpc.Ua.XRegistry,Opc.Ua.XRegistry.Client, andOpc.Ua.XRegistry.Server. - PubSub (Part 14) - Publisher/subscriber support library: architecture, fluent builder, transports (UDP / MQTT 3.1.1 + 5.0 / Kafka / Ethernet Layer 2), encodings (UADP / JSON), security, and server-side address space.
- PubSub High Availability - Distributed Part 14 §9.1.6 active/standby publishers and subscribers with Cold/Warm/Hot modes, leader election or fenced leases, shared runtime checkpoints, protected SKS key storage, consistency guidance, and Kubernetes deployment notes.
- Migration sub-doc - 1.5.378 → 2.0 breaking API, transport, JSON, and field-encoding changes, plus the compatibility matrix.
- Ethernet transport - Layer 2 PubSub (
opc.eth://, EtherType0xB62C, 802.1Q VLAN) with native AF_PACKET / BPF, SharpPcap, and in-memory backends. - Kafka transport - Apache Kafka broker transport (
kafka://,kafkas://) for UADP and JSON PubSub profiles with SASL/TLS and NativeAOT support onnet10.0. - PubSub Transcoding - In-process subscriber-to-publisher transcoding with UADP/JSON cross-encoding, field/value/metadata transforms, identifier remap, receive hooks, egress, and managed UADP re-securing.
- External server adapter - Bind PubSub publishers, subscribers, and Action responders to an external OPC UA server through
ManagedSession. - Dependency Injection extensions -
AddPubSub,AddPubSubPublisher,AddPubSubSubscriber,AddPubSubSecurityKeyServiceClient/Server,AddPubSubAddressSpace. - Profiles - Datagram-v2, SKS pull / push, AES-128/256-CTR security facets.
- PubSub Diagnostics - packet capture, dissection and replay of UDP / MQTT PubSub traffic, including decryption of encrypted UADP messages.
Reference application related
- Reference Client documentation for configuration of the console reference client using parameters.
- Reference Server documentation for running against CTT.
- ConsoleReferencePubSubClient documentation for the PubSub reference sample (publisher / subscriber / external-server adapter modes).
- Provisioning Mode for secure certificate provisioning and initial server configuration.
- Using the Container support of the Reference Server in Visual Studio 2026 and for local testing.
Starting with version 1.5.375.XX the Windows Forms reference client & reference server were moved to the OPC UA .NET Standard Samples repository.
Global Discovery Server (GDS)
- GDS Developer Guide — Application registration, certificate management (pull & push models), roles and authorization, OPC 10000-21 registrar ticket administration, provider implementation, the runnable
samples/Gdsonboarding demo, and a per-requirement OPC UA Part 12 conformance matrix. - KeyCredentialService — Credential issuance for non-OPC UA services (MQTT, REST), IKeyCredentialRequestStore provider guide, ISecretStore integration.
- AuthorizationService — OAuth2-style access token issuance, IAccessTokenProvider implementation guide.
- Role-Based Security — Part 18 roles and claim-based identity-mapping rules.
- Identity Providers — server and client identity-provider architecture.
- Dependency Injection — dependency injection hosting and identity registration extensions.