UA-.NETStandard/docs/WhatsNewIn2.0.md

What's New in OPC UA .NET Standard 2.0

Version 2.0 expands the SDK beyond the 1.5.378 client/server APIs with managed connections, model-driven application development, injectable services, and distributed deployment options. This overview highlights what those changes enable; the linked guides contain API contracts, examples, and limitations.

Contents

• At a glance
• Feature details
  • Dependency injection and hosting
  • Client
  • Source generators and modeling
  • Type system and immutability
  • Performance, memory, and pooling
  • Async, cancellation, and TimeProvider
  • Native AOT
  • OPC UA companion-spec coverage
  • Security and certificates
  • Global Discovery Server
  • Part 14 PubSub modernization
  • High availability and redundancy
  • Tooling and diagnostics
• Further reading

At a glance

Area	What 2.0 enables
Application development	Host clients and servers through one dependency-injection builder; generate model types and typed client proxies instead of writing service plumbing.
Client connections	Use ManagedSession for reconnection and failover, with callback-based or asynchronous streaming subscriptions.
Data and deployment	Use strongly typed values, arrays, and matrices; publish supported applications with Native AOT.
Server capabilities	Add historian providers, alarms, state machines, file access, and the models in the specification catalogue through reusable services.
Security and discovery	Manage certificate lifecycles and identities through providers, and integrate GDS pull/push management and token services.
PubSub and availability	Compose publishers/subscribers with transport packages, or opt into redundancy and distributed state for client/server deployments.

Feature details

Dependency injection and hosting

services.AddOpcUa() provides a common entry point for clients, servers, and feature libraries. The .NET Generic Host manages server lifetime; options, telemetry, identities, certificates, and application providers use the same container. Direct construction remains available. See Dependency Injection.

Client

ManagedSession manages connection recovery behind a fluent builder while the classic Session remains available for applications that own that lifecycle. The V2 subscription API adds options-based callbacks, triggering relationships, automatic partitioning, and IAsyncEnumerable streams for short-lived monitoring. Typed helpers cover history, alarms, files, and model-change tracking. Opt-in session-less invocation supports the service sets permitted by OPC 10000-4 without creating a Session; subscriptions still require one. HTTPS and WebSocket OpenAPI mappings also support web-facing integration. Generation-bound session clients capture a transport/session generation and namespace mappings. An invalidated binding fails instead of silently retargeting requests after a reconnect. See Sessions, Subscriptions, File System Client, and Model Change Tracking.

Source generators and modeling

ModelDesign and NodeSet2 inputs generate node-manager scaffolding, state types, and typed ObjectType client proxies. POCO annotations generate IEncodeable implementations, and model dependencies can be registered across assemblies. Models that change independently of the binary can instead be loaded at runtime. Fluent complete Method results carry operation diagnostics, ordered input-argument results and output values. Forwarded diagnostics are resolved into the receiving response's string table, subject to diagnostic requests and authorization. See Node Managers, Source-Generated Data Types, Model Dependencies, and Runtime NodeSets.

Type system and immutability

Readonly value types and the Variant-based API reduce boxing and make OPC UA values explicit. ByteString, ArrayOf<T>, and MatrixOf<T> represent binary, array, and matrix data. Runtime complex-type loading supports server-defined structures and enumerations without requiring a generated CLR class for each type. See Complex Types and Schema Generation.

Performance, memory, and pooling

Value-type representations and pooled buffers reduce allocations in encoding and notification paths. Server work also improves resource lifetime and repeated permission checks. These changes do not imply that every workload is faster; use the measured results and sizing guidance for your deployment. See Benchmarks, Server Scalability, and Rate Limiting.

Async, cancellation, and TimeProvider

AsyncCustomNodeManager supports asynchronous service and data-source operations. Request cancellation follows the request lifetime, while TimeProvider enables controlled clocks and timers for testing. Existing synchronous compatibility APIs do not make blocking waits appropriate in new asynchronous handlers. Dynamic node removal can await final-value publication through the existing subscription engine. The boundary is inclusion in the server's Publish response, not a client transport acknowledgment. See Async Server Support and Node Managers.

Native AOT

Source-generated models, runtime type representations, and revised serialization paths support applications published without a JIT compiler. Choose AOT-compatible providers and the default complex-type builder; the optional Reflection.Emit builder still requires runtime code generation. See Native AOT: publish an application and Complex Types.

OPC UA companion-spec coverage

The SDK adds model libraries, hosting support, and client helpers for the following services and domains. Core OPC UA specification parts are listed separately from domain-specific companions and draft extensions.

Core specification services and models

Capability	Specification	Guide
Alarms and conditions	OPC 10000-9	Alarms and Conditions
Historical access and aggregates	OPC 10000-11 and OPC 10000-13	Historical Access and Aggregates
State machines	OPC 10000-16	State Machines
Alias names	OPC 10000-17	Alias Names
Node and reference management	OPC 10000-4	Node Management
File transfer and file systems	OPC 10000-5 Annex C and OPC 10000-20	File System Client
Roles and user management	OPC 10000-18	Role-Based User Management
Global discovery and certificate management (GDS)	OPC 10000-12	Global Discovery Server
Local discovery (LDS and LDS-ME)	OPC 10000-12	LDS / LDS-ME and the Console LDS Server sample
Device onboarding: registrar ticket administration	OPC 10000-21	OnboardingClient and the onboarding sample

Companion and extension models

Domain	Specification or status	Guide
Device composition and software updates	OPC 10000-100 (Devices)	Device Integration and Software Update
Asset discovery, health, maintenance, documentation and location	OPC 10000-110 (Asset Management Basics)	Asset Management Basics
Machines, job management, process values, energy and result transfer	OPC 40001-1/-2/-3/-4/-101 (Machinery), with OPC 34100 (Energy Consumption Management) and OPC 30081 (PA-DIM)	Machinery
Machine monitoring, tools, production and wireless peripherals	OPC 40501-1 (MachineTool) and OPC 40505 (WMTP); both models share the MachineTool packages	MachineTool and WMTP
Geometric measurement systems, qualification and results	OPC 40210 (GMS); the undefined upstream production-statistics CU prevents claiming the complete Production facet	GMS
Crane systems, loads, protection observations and limit requests	OPC 40020-1 (Cranes and Hoists); preview packages, with equipment behavior supplied by providers	Cranes and Hoists
Pumps, compressors and vacuum pumps	OPC 40223 (Pumps and Vacuum Pumps)	Pumps
Scales and scale systems	OPC 40200 (Weighing Technology), with OPC 30050 (PackML)	Scales
Motion-device systems and controllers	OPC 40010-1 (Robotics), over OPC 10000-200 (Industrial Automation, its own Opc.Ua.IA package)	Robotics
Task-level robot commands	Robot Intent (draft)	Robot Intent
Manufacturing resources and job control	OPC 10030 (ISA-95 Common Model) and OPC 10031-4 (Job Control V1/V2)	ISA-95
Relative and geographic positioning	OPC 10000-210 (RSL) and OPC 10000-211 (GPOS)	Positioning
Machine Vision control, recipes, configuration, results and assets	Released OPC 40100-1 and OPC 40100-2	Machine Vision
Perception, media, inference and feedback	Vision Perception (draft); distinct from the released Machine Vision models	Perception
Model catalogues, deployments, and inference	AI Model Management and Inference (draft)	AI Model Management
Resource registration, versioning, and federation	xRegistry abstract base model (draft)	xRegistry
Scene bindings and address-space materialization	OpenUSD Bindings and OpenUSD Scene (both draft)	OpenUSD
Web of Things connectivity and conversion	OPC 10100-1, with preview registry extensions	WoT Connectivity, WoT / NodeSet Conversion, and WoT Bindings

The draft Generators model in the generator server is a sample-local model, not a standalone SDK library.

Draft entries are identified by model name rather than an unverified specification number; their namespace URIs and NodeIds remain provisional. The guides describe provider requirements and supported operations. Model coverage does not imply complete runtime implementation or certification for every specification. Package channel and model maturity are independent: a released specification can ship in a preview-only package. The release policy defines the package families that remain preview-only.

Security and certificates

Reference-counted certificates and CertificateManager provide explicit ownership, trust-list management, rotation, and lifecycle notifications. Identity providers support application-specific authentication. Pluggable crypto providers let an application replace platform cryptography with another library, a remote service, or hardware such as a TPM, HSM, or PKCS#11 token. Providers can be selected by purpose and security policy, including support for hardware-held private keys. ECC SecureChannel and user-token policies, including the AEAD variants, are available on every target; on .NET Framework the ECDH agreement and the AES-GCM and ChaCha20-Poly1305 ciphers use BouncyCastle. Curve and cipher availability also depends on the platform. See Certificate Manager, Identity Providers, Crypto Providers, and ECC Profiles.

Global Discovery Server

GDS support extends application registration, pull/push certificate management, custom certificate groups, token issuance, and credential services. A Local Discovery Server is also available as a hosted component or standalone sample. For OPC 10000-21 device onboarding, clients register and unregister tickets with a device registrar through OnboardingClient, and the registrar keeps them in a pluggable ITicketStore. See GDS for capability boundaries and conformance evidence, Authorization Service, and Key Credential Service.

Part 14 PubSub modernization

A fluent builder and dependency-injection extensions compose PubSub applications from separate runtime, transport, and server-integration packages. UADP and JSON encoding, discovery, retained metadata, runtime configuration, diagnostics, and Security Key Service integration support publisher/subscriber workflows. UDP/DTLS, Ethernet, MQTT and Kafka transports use their corresponding packages; the Kafka package supplies the Part 14 broker mapping rather than requiring an application-specific transport implementation. Transport and cryptographic capabilities remain platform-dependent; in particular, the DTLS Curve25519 / Curve448 profiles are not registered. See PubSub for supported profiles, transports, and examples.

High availability and redundancy

Server redundancy metadata and ManagedSession failover support OPC UA redundancy workflows. Optional distributed stores add address-space, session, and subscription mirroring with eventual or strong consistency choices. Kubernetes integration provides deployment, discovery, and readiness support. See High Availability, Replica-Consistent NodeIds, and Kubernetes for configuration and deployment constraints.

Tooling and diagnostics

The MCP server exposes client operations and packet-capture tools to agents. Bounded companion profiles include MachineTool with WMTP, GMS, CranesHoists, Vision, Robotics, AMB, Machinery, Scales, Pumps, Device Integration, ISA-95 and Positioning. They compose over named sessions without duplicating connection tools. Dedicated profiles also cover WoT/xRegistry documents, GDS, reference-only credentials, roles/users, files, alarms, history and schemas. Live WoT and PubSub workflows require explicit host capabilities and operation or network grants; selecting a catalogue is not permission to execute it. The adapters reuse the stack's typed client workflows. ITelemetryContext supplies application logging, metrics, and tracing, with audit and redaction support. A migration analyzer and code fixer assist with mechanical API updates. See MCP Server and Diagnostics.

Further reading

• Migration Guide — breaking changes, per-API replacements, and the migration analyzer workflow for upgrading from 1.5.378.
• Documentation index — task-based routes into the SDK guides.
• Sample applications — runnable client, server, PubSub, and companion-model examples.
• Profiles and facets — capability and platform overview.