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Marc Schier
a7c776e8d4
# Description Aligns the WoT implementation with the normative changes in the OPC UA WoT specification drafts that the stack had not picked up, and fixes the defects that alignment surfaced. The driving artifact is [OPCF-Members/spec-drafts#19](https://github.com/OPCF-Members/spec-drafts/pull/19), *"bind a projected node to an already-loaded type, by name or by NodeId"*, which landed on the spec `main` after this repository last tracked it. ## 1. Bind a projected node to an existing type (Binding §5.2.1) §5.2.1 lets a document state that the node it projects is an instance of a type that **already exists** — one a companion model defines and the Server has loaded, or one a sibling document of the same conversion defines — so a converter binds to that type instead of defining a second type of the same shape. The converter hardcoded `HasTypeDefinition` to `BaseObjectType`, so a document that named its type projected an **untyped** node: a client browsing for the companion type would not find it, and nothing said why. Both forms are now implemented, resolved against the §5.1.5 **local context** — the other documents being converted together first, a loaded AddressSpace as the fallback. `IWotNodeResolver` supplies that context (is a namespace held; what does a qualified BrowseName match; what does an ExpandedNodeId identify), `WotCompositeNodeResolver` composes implementations in the specified order, and `NullWotNodeResolver` is the default that holds nothing. The converter needed no new async surface: the binding is resolved in a pre-resolve pass, exactly as Thing references already are, and the synchronous core consumes the result. The §5.2.1 table is honoured: a unique name binds; the link settles an ambiguous name; a name that resolves to nothing while the link resolves is **invalid** (that is a mistake in the name, not a shorthand for the identifier); two forms resolving to different Nodes are invalid; a resolved type of the wrong NodeClass is invalid. A binding naming a type the local context does not hold **fails** rather than falling back to `BaseObjectType` — a silently mistyped node is worse than a reported failure. A compact name is told from ordinary `@type` annotation **by namespace**, not by whether the lookup succeeds, so `saref:TemperatureSensor` on a Server that has never heard of SAREF stays the annotation it always was. The definitive form — a `ua:HasTypeDefinition` link whose `href` is the ExpandedNodeId of the type. An ExpandedNodeId matches exactly one Node or none, so it needs no lookup. A Node has exactly one `HasTypeDefinition`, so: - two such links → `AmbiguousTypeBinding` (6019), and the root keeps the default rather than being bound to a guess; - a link with no usable identifier → `InvalidTypeBinding` (6020); - no binding at all → the `BaseObjectType` default is unchanged. ## 2. Drop the six vocabulary terms `#19` removed `#19` deleted `uav:capability`, `uav:componentModel`, `uav:reference`, `uav:congruentType`, `uav:congruentTypeName` and `uav:nameNamespace` from the context, the JSON Schema and the ontology. A link now names its ReferenceType directly in `rel`, so the three link relations become `ua:HasInterface`, `ua:HasComponent` and `ua:NonHierarchicalReferences`, and the congruent-type pair is superseded by the §5.2.1 type binding. Their validation and mapping are removed; they are now ordinary residue like any other unrecognised term. ### A real gap this uncovered The converter knew **eight** ReferenceTypes by name and had neither `NonHierarchicalReferences` (`i=32`) nor `HasInterface` (`i=17603`) — so the two relations that *replace* `uav:reference` and `uav:capability` could not resolve at all. That includes example 02, which this repository vendors as a golden asset and which `#19` rewrote to use them. Both are now in the map. `uav:congruentType` was also the only term that redirected one reference to another while resolving a link target, so `ResolveTargetNodeIdAsync` no longer needs a loop. It resolves once and reports an unresolved target; the resolution context is still entered and the bytes still counted, so the per-conversion document, depth and byte bounds are unchanged. ## 3. Reject an out-of-range event severity instead of clamping it `uav:severity` had grown in this implementation without being a specification term. Rather than drop it, it is proposed upstream in [OPCF-Members/spec-drafts#21](https://github.com/OPCF-Members/spec-drafts/pull/21), which defines it with an explicit rule: the value **shall** be in the OPC 10000-5 range 1..1000, and a consumer **shall not** silently clamp it. The implementation clamped, so a document asking for severity 5000 was accepted and published as 1000 — the mistake was hidden while what the author asked for was changed. An affordance carrying an out-of-range severity is now skipped, with the reason logged, and its half-built event type and `GeneratesEvent` reference are removed. ### Defect found while making that change The occurrence-time path read `ValidateSeverity(severity) ?? tag.Severity`. Because `ValidateSeverity(null)` returns the 500 default, it **never** fell back to the affordance's authored severity: an occurrence reported without a severity published 500 rather than the authored 900. Build-time validation and the occurrence-time choice are now separate methods. ## 4. Vendored examples and honest coverage claims Examples 21 and 22 were missing from the vendored golden assets. Converting example 22 is now the end-to-end check for §5.2.1 — the specification's own example rather than a fixture written to match the implementation. `docs/WotBindings.md` claimed ten of the eleven conformance units and silently omitted **WoT-ConditionMapping**, and said "twenty worked examples". The count is corrected, and WoT-ConditionMapping is now **covered** — see §5 below. ## 5. Alarms and Conditions (Binding §13) The last unclaimed conformance unit. A projected Condition event now derives from the ConditionType it names rather than from `BaseEventType`; falling back would lose the Condition state model entirely, leaving a Client unable to tell an alarm from an ordinary event. The two forms follow the hint-plus-pin pattern of §5.3: `uav:conditionTypeId` is definitive and wins, `uav:conditionType` is a readable hint resolved for the four ConditionTypes §13.1 scopes. An unpinned name outside that set is reported rather than guessed. Four conformance rules are enforced, each because breaking it yields a document a consumer can read but cannot act on: | Rule | Section | Diagnostic | | --- | --- | --- | | A Condition event declares `EventId` in its `data` | 13.3 | `ConditionEventIdMissing` | | `uav:conditionAction` is inside its closed set | 13.2 | `InvalidConditionAction` | | `uav:actsOn` names a Condition event in the same document | 13.4 | `InvalidConditionTarget` | | `Acknowledge`/`Confirm`/`AddComment` declare an `EventId` input | 13.4 | `ConditionActionInputMissing` | `Enable` and `Disable` act on the Condition instance rather than one occurrence and are deliberately exempt from the last rule, pinned by a negative test. Shelving, suppression, dialog conditions and `ConditionRefresh` stay out of scope, as §13.1 scopes the mapping. ## 6. The sibling half of the §5.1.5 local context `SnapshotWotNodeResolver` indexes the registry snapshot a conversion runs over and is wired into `WotNodeSetDocumentConverter`, so a document naming a type another document in the same registry projects resolves with no AddressSpace at all. Only Thing Models are indexed: a Thing Model projects a `UAObjectType` and is a valid target, a Thing Description projects an instance and never is. Identity comes from the new public `WotNodeSetConverter.TryDescribeProjectedType`, which applies exactly the rules the conversion uses, so an index entry and the projected node cannot drift apart. Ambiguity is preserved rather than resolved: two siblings sharing a qualified name yield both matches so the caller can report it. ## Deliberately not in this PR - **The AddressSpace-backed `IWotNodeResolver`.** The abstraction, the composite, the null default and the sibling-document implementation ship here; the AddressSpace-backed half needs a cached type-hierarchy walk behind a server `OperationContext` and follows separately. Until it exists a host gets the sibling context plus the null fallback, which reports a binding as unresolved rather than mistyping it. - **Two §5.2.1 obligations that need the address space**: not duplicating a mandatory instance declaration of the resolved type, and rejecting disagreement with an instantiated Thing Model. - **Connectivity §7.3 parent resolution.** Each is tracked; none is faked here. ## Related Issues There is no tracking issue: this came out of a spec-versus-implementation audit rather than a reported defect, and the driving artifacts are the two upstream spec PRs linked above. Happy to open one if maintainers prefer — the §5.2.1 follow-up in particular is worth an ADR, since the local-context resolver is a new injectable provider spanning two assemblies. ## Checklist - [x] 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. ### Verification detail | | net10.0 | net48 | |---|---|---| | `Opc.Ua.Types.Tests` | 8573 / 8573 | 8555 / 8555 | | `Opc.Ua.WotCon.Tests` | 1075 / 1075 | 1075 / 1075 | Full `UA.slnx` build: **0 errors, 0 warnings** across all target frameworks, re-verified after `master` was merged into the branch. Every new test was mutation-verified: the type-binding tests against three mutations (revert to the hardcoded default, drop the ambiguity check, accept an empty `href`), the severity tests against reinstating the clamp, and the ReferenceType additions against removing them from the map. Each mutation failed the suite before the change was kept. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 9e6a5abf-3299-4cd1-9855-010fedbf0ad8
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).
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.OpenUsdScenecompanion model plus scene document model,.usdareader/writer and the §6.2UsdValueTypeMap(USD roles as DataTypes subtyping their built-in), andOpc.Ua.OpenUsdScene.ServerwithMaterializeUsdStage/ExportUsdStage, unknown-type fallbacks, Mode-A live attributes, portable Cesium georeference dual-authoring, discovery and Part 1 binding-target resolution. (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. - 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 reads, annotations, and 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.- 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).
- Kubernetes High Availability Deployment - Consolidated Kubernetes guide for the
- 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-agnostic content-addressed resource registry:
IResourceContentIdProvideridentity, the Opaque-NodeId fast path (resolve a resource in oneRead), theCreateResource/Write/Closeregistration lifecycle with auto-bootstrap, federated resource proxies, and the 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, provider implementation, end-to-end examples, and a per-requirement OPC UA Part 12 conformance matrix that links every implemented ServerConfiguration/PushManagement, TrustList, certificate-alarm, KeyCredentialService and AuthorizationService requirement to its source and automated tests (with applicable profiles/conformance units and honest complete/partial/optional/unsupported marks).
- 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.