UA-.NETStandard/Docs

OPC UA .NET Standard stack documentation

Here is a list of available documentation for different topics:

UA Core stack related

• OPC UA Profiles and Facets - Overview of supported OPC UA profiles, facets, security policies, and transport protocols.
• 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.
• How X.509 Certificates are used in the certificate stores.
• Using the Reverse Connect for the UA-TCP transport.
• Support for the TransferSubscriptions service set.
• Observability support in the stack.
• Support for WellKnownRoles & RoleBasedUserManagement.
• Pluggable Identity Providers — interfaces (IClientIdentityProvider, IUserTokenAuthenticator, IAccessTokenProvider, ITokenIssuer, IIdentityClaims) plus the OPC 10000-6 §6.5.2.2 IssuerEndpointUrl JSON 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 IEncodeable implementation.
• Source generated NodeManagers - Emit an AsyncCustomNodeManager from a model design XML and wire callbacks via the fluent INodeManagerBuilder API; supports NativeAOT single-file servers (samples: MinimalBoilerServer, PumpDeviceIntegrationServer). Covers engineering units, property initialisation, alarms, simulation timers, instance creation, NAMUR-style supervision, multi-model composition, and the fluent state-machine builder on top of any FiniteStateMachineState subclass. Cross-assembly model references are tracked via the ModelDependencyAttribute. Companion-spec packaging — model + server + client library trios — is covered end-to-end by the Device Integration developer guide using the Opc.Ua.Di / Opc.Ua.Di.Server / Opc.Ua.Di.Client trio as the worked example.
• Device Integration (DI) developer guide - End-to-end documentation for the Opc.Ua.Di* library trio: fluent IDeviceBuilder, 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.
• 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, fluent AlarmEventFilterBuilder, IAsyncEnumerable alarm streaming via AlarmStreamExtensions.
• Historical Access (Part 11) - Server provider model (IHistorianProvider family) and InMemoryHistorianProvider, plus the client HistoryClient (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, AnnotationCount via the annotation provider, AggregateConfiguration defaults, and the client ReadProcessedAsync helper.
• Streaming Subscriptions - IAsyncEnumerable-based subscription API for state-machine waits and short-lived monitoring (IStreamingSubscription, ManagedSession.DefaultStreaming, TakeUntilAsync / WithTimeoutAsync helpers).
• State Machines - Generic, extensible Part 16 state-machine API. Client side: streaming + read helpers on the source-generated *TypeClient proxies (GetCurrentFiniteStateAsync, ObserveFiniteTransitionsAsync, WaitForStateAsync). Server side: unified fluent StateMachineBuilder with two complementary modes — definition (Create(...) + AddState / AddTransition / OnCause for ad-hoc machines via FluentFiniteStateMachineState) and lifecycle (For(...) / INodeBuilder.AsStateMachine() + OnEnterState / WithCause / WithTimedTransition to 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 INodeCache invalidation; server-side ModelChangeAggregator and auto-emitted GeneralModelChangeEvent from CustomNodeManager.CreateNode/DeleteNode.
• NodeManagement Service Set - Server-side AddNodes / DeleteNodes / AddReferences / DeleteReferences, including the INodeManagementAsyncNodeManager opt-in pattern and per-NodeManager AllowNodeManagement gate.
• Dependency Injection - The unified services.AddOpcUa() / IOpcUaBuilder surface for hosting OPC UA components in Microsoft.Extensions.DependencyInjection / the .NET Generic Host (servers as IHostedService, options via Action<T> or IConfiguration, AOT-friendly).
• AuthorizationService - Modern Part 12 StartRequestToken / FinishRequestToken, ITokenIssuer, and GDS token issuance.
• KeyCredentialService - Pull, Push, and experimental bridge guidance for Part 12 KeyCredential flows.

Reference application related

• Reference Client documentation for configuration of the console reference client using parameters.
• Reference Server documentation for running against CTT.
• 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.

For the PubSub support library

• The PubSub library with samples.
• The ConsoleReferencePublisher documentation.
• The ConsoleReferenceSubscriber documentation.

Global Discovery Server (GDS)

• GDS Developer Guide — Application registration, certificate management (pull & push models), roles and authorization, provider implementation, end-to-end examples.
• 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.