# Description The CTT AliasName conformance units skip or fail against the ConsoleReferenceServer. `AliasName Base` skips with *"No instance of AliasNameType has been found in the address space"*; `Category Tags`, `Category Topics` and `Hierarchy` fail. Part 17 support landed in #3779, but aliases live only inside the `IAliasNameStore` — nothing is browsable, no `AliasNameCategoryType` is nested under another, and the Topics aliases point at the Server object rather than at a `PublishedDataSetType` instance. Part 17 §6.2 clients — the CTT among them — discover aliases by browsing, not only by calling `FindAlias`. This PR materializes the store contents as real nodes and fills the three gaps. ### SDK — `Opc.Ua.Server` * **`DiagnosticsNodeManager.MaterializeRegisteredAliasNameNodesAsync`** (new, opt-in) walks every registered `IAliasNameStore` and creates one `AliasNameType` instance per alias — BrowseName carrying the alias name, `AliasFor` references to its targets, and the inverse `HasAlias` reference on each local target (via `externalReferences`, since targets usually live in another node manager) — plus an `AliasNameCategoryType` instance for every store category the standard NodeSet does not already ship. Categories whose NodeId belongs to another node manager are skipped, so an `AliasNameNodeManager` that also registers its store with the server-wide registry does not get its NodeIds claimed twice. Opt-in: servers that only need the well-known `FindAlias` to answer from their store pay nothing. The nodes are a snapshot taken at address-space creation — later mutations change what `FindAlias` returns but do not add or remove nodes. * **Optional Part 17 methods on the well-known categories.** The same pass instantiates whatever a category declares through `AliasNameCapabilities`: `FindAliasVerbose` (§6.3.3), `AddAliasesToCategory` (§6.3.4), `DeleteAliasesFromCategory` (§6.3.5) and `LastChange` (§6.3.1). Mutations require a `SecurityAdmin` caller on a `SignAndEncrypt` channel; the gate previously private to `AliasNameNodeManager` moved to `AliasNameMethodDispatcher` so both paths share one implementation. * **`LastChange`** is now tracked per category rather than only for the standard `Aliases` node, and the duplicated seeding logic collapsed into one helper. ### Reference server * A nested **`Devices`** category under `TagVariables` holds `Pump1_Status` and `Heater_Power`. `FindAlias` on `TagVariables` still returns all six names through subtree recursion, while `FindAlias` on `Devices` returns exactly two — which is what the Hierarchy unit checks. * `ReferenceServerConfigurationNodeManager` creates three **`PublishedDataSet` instances** under `PublishedDataSets` (`i=17371`) and the Topics aliases now target them, satisfying the *"is a Dataset"* check. These are address-space instances only — no PubSub runtime is added, and the CTT only inspects the target's type definition. ## Note for reviewers — the reserved NodeIds The optional children are created at the NodeIds the OPC Foundation reserves for them (`Aliases.FindAliasVerbose` = `i=24054`, `TagVariables.LastChange` = `i=32854`, …). Those identifiers are allocated in `StandardTypes.csv` but are **not** declared in the ModelDesign and **not** present in the published NodeSet, because the standard address space does not instantiate optional children. The source generator therefore emits no parent-to-instance mapping and no `MethodIds` constants for them, so `DiagnosticsNodeManager.ReservedChildIds` supplies the nine method ids and the two missing `LastChange` ids explicitly, each traceable to its registry row. The 18 argument-property ids do have generated `VariableIds` constants and are referenced through those. I deliberately did **not** "fix" this by declaring the children in `tools/Opc.Ua.SourceGeneration.Core/Design/StandardTypes.xml`: that file is a verbatim copy of upstream `UA-ModelCompiler/Design.v105/StandardTypes.xml` (the only differences today are upstream being newer), so a local edit is lost on the next sync and the NodeIds would silently revert to factory-minted ones. `docs/AliasNames.md` records this. Worth raising upstream separately: `StandardTypes.csv` allocates `Aliases_FindAliasVerbose` and siblings while the ModelDesign never declares those children, so the ModelCompiler cannot emit ids it has itself reserved. If that is ever reconciled, `ReservedChildIds` becomes redundant and deletes cleanly. ## Related Issues - Fixes #4012 ## 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. - [ ] I ran **all** tests locally using the **UA.slnx** solution against at least .net **framework** and .net **10**, and all passed. — **not done: verified on net8.0 only** (Server 4710, InformationModel 1099, Core 4443, plus the client and features alias suites; AOT build clean). Needs a run against net framework and net10 before this leaves draft. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received. ### Tests `tests/Opc.Ua.InformationModel.Tests/Aliasname*Tests.cs` mirror the four CTT conformance units and no longer `Assert.Ignore` where the CTT reported failures — the alias suite is 37 tests with no skips. New `AliasnameOptionalMethodsTests` covers the optional methods, their reserved NodeIds, the anonymous-caller denial, an add/find/delete round trip and `LastChange` advancing on mutation. One pre-existing test changed premise: `EnumerateSubCategoriesAsyncOnLeafReturnsEmptyAsync` asserted that `TagVariables` has no sub-categories, which this PR deliberately makes false. It now targets `Topics` (still a leaf) and a new test guards the nesting. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com> Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: romanett <7413710+romanett@users.noreply.github.com> Co-authored-by: marcschier <11168470+marcschier@users.noreply.github.com>
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
- Open the solution UA.slnx with Visual Studio 2026.
- Choose the project
Reference Serverin the Solution Explorer and set it with a right click asStartup Project. - Hit
F5to 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
- Open a command prompt.
- Navigate to the folder samples/Reference/ConsoleReferenceServer.
- 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:
AlarmConditionTypeDiscrepancyAlarmTypeLimitAlarmTypeExclusiveLimitAlarmTypeExclusiveDeviationAlarmTypeExclusiveRateOfChangeAlarmTypeNonExclusiveLimitAlarmTypeNonExclusiveDeviationAlarmTypeNonExclusiveRateOfChangeAlarmTypeDiscreteAlarmTypeSystemOffNormalAlarmTypeExclusiveLevelAlarmTypeNonExclusiveLevelAlarmTypeOffNormalAlarmType
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