Files
UA-.NETStandard/samples
Marc Schier a7c776e8d4 Align the WoT implementation with spec: type binding, removed vocabulary, Alarms and Conditions (#4225)
# 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
2026-08-14 07:55:33 -07:00
..

OPC Foundation UA .NET Standard Reference Server

Introduction

This document is referring to the CTT version 1.04.9.398.

This OPC Server is designed to be the default OPC UA Server when opening the OPC UA Compliance Test Tool and it uses an address-space that matches the design of the UACTT and the requirements for OPC UA compliance testing.

It uses the OPC Foundation UA .NET Standard Library. Therefore it supports both the opc.tcp and https transports. There is a .NET framework based server with UI and a .NET Core console version of the server which runs on any OS supporting .NET Standard 2.1 or .NET 8.0 and later.

How to build and run the Windows OPC UA Reference Server with UACTT

  1. Open the solution UA.slnx with Visual Studio 2026.
  2. Choose the project Reference Server in the Solution Explorer and set it with a right click as Startup Project.
  3. Hit F5 to build and execute the sample.

How to build and run the console OPC UA Reference Server on Windows, Linux and iOS

This section describes how to run the ConsoleReferenceServer.

Please follow instructions in this article to setup the dotnet command line environment for your platform.

Start the server

  1. Open a command prompt.
  2. Navigate to the folder samples/ConsoleReferenceServer.
  3. To run the server sample type dotnet run --project ConsoleReferenceServer.csproj. The server is now running and waiting for the connection of the UACTT.

UACTT test certificates

The reference server always rejects new client certificates and requires that the UACTT certificates are in appropriate folders.

  • The console server certificates are stored in %LocalApplicationData%/OPC Foundation/pki.
  • The Windows .NET framework server stores the certificates in %CommonApplicationData%\OPC Foundation\pki.
    • %CommonApplicationData% maps to the path set by the environment variable ProgramData on Windows.
    • %LocalApplicationData% maps to a hidden location in the user home folder and depends on the target platform. See Certificates for more information.

Certificate stores

Under pki, the following stores contain certificates under certs, CRLs under crl or private keys under private.

  • own contains the reference server public certificate and private key.
  • rejected contains the rejected client certificates. To trust a client certificate, copy the rejected certificate to the trusted/certs folder.
  • trusted contains trusted client and CAs certificates and CRLs.
  • issuer contains CAs certificates and CRLs needed for validation.
  • trustedUser contains trusted user and user CA certificates and CRLs.
  • issuerUser contains user CA certificates and CRLs needed for validation of the certificate chains.

Placing the UACTT certificates

CTT creates a PKI folder in a new project. There is a subfolder copyToServer which contains the application and user identity certificates. Copy the ApplicationInstance_PKI certificates for testing with the UACTT to the following stores:

  • trusted/certs: trusted certificates
  • trusted/crl: revocation lists of trusted certificates
  • issuer/certs: issuer certificates
  • issuer/crl: revocation lists of issuer certificates

Copy the X509UserIdentity_PKI certificates for testing with the UACTT to the following stores:

  • trustedUser/certs: trusted user certificates
  • trustedUser/crl: revocation lists of trusted user certificates
  • issuerUser/certs: user issuer certificates
  • issuerUser/crl: revocation lists of user issuer certificates

UACTT Testing

Download and install the OPC UA Compliance Test Tool.

Note: Access to the UACTT is granted to OPC Foundation Corporate Members.

UACTT sample configuration

A sample configuration for the UACTT Version 1.04.9.398 can be found in UAReferenceServer.ctt.xml. Originally the reference server was certified only against the Standard UA Server profile, the Method Server Facet and the DataAccess Server Facet, in addition to all security related profiles. During release testing all Conformance Units should be enabled / checked.

Enabling Alarms & Conditions

The address space for Alarms contains a Start method which needs to be called to produce alarms for CTT testing. The method is called from a connected client. The ConsoleReferenceServer has also a command line option -ctt which starts the Alarms when the server is started. The following Alarm instances are available for monitoring:

  • AlarmConditionType
  • DiscrepancyAlarmType
  • LimitAlarmType
  • ExclusiveLimitAlarmType
  • ExclusiveDeviationAlarmType
  • ExclusiveRateOfChangeAlarmType
  • NonExclusiveLimitAlarmType
  • NonExclusiveDeviationAlarmType
  • NonExclusiveRateOfChangeAlarmType
  • DiscreteAlarmType
  • SystemOffNormalAlarmType
  • ExclusiveLevelAlarmType
  • NonExclusiveLevelAlarmType
  • OffNormalAlarmType

Known missing Tests and Issues

Depending on the setup in the provided project configuration, unsupported profiles should be skipped. At the time of writing (1.4.368) the following tests, profiles or facets are not yet covered or not configured due to issues:

  • no support for events, historian and only a few basic Alarms & Conditions.
  • Decimal type causes crash of CTT (needs investigation)
  • no Image / Enumeration scalar test cases
  • Arrays may not include Variant (needs investigation)
  • no ArrayItemType implemented
  • multiple hierarchical references test node missing
  • deprecated security profiles support for SHA1/1k RSA keys implemented not according to certification. SHA1/1k keys can only be turned on/off for all profiles, not just for the deprecated profiles.
  • Monitored Items with array are failing a few test cases.

It is recommended to run the server as retail build with disabled logging, to avoid side effects due to timing artifacts when log entries are written to a disk drive.

Running the CTT against a Docker container

Please refer to the Docker container of the Reference Server documentation page. Once setup to map the certificate store and the configuration to a local folder, follow the instructions above to copy the certificates to the PKI and get started.

Finding the Address Space Configuration Code

  • Project: Reference Server
  • File: ReferenceNodeManager.cs
  • Method: CreateAddressSpace

Finding the UA Services

  • Project: Opc.Ua.Server
  • File: StandardServer.cs