1 Commits

Author SHA1 Message Date
Klaus Landsdorf cc7908eaa1 WebApi: serve a generated OpenAPI document of the REST binding (opt-in) and map the session-less service set (#4657)
Reworked after the review: the OpenAPI document is generated from the
code, not embedded; the route is opt-in; `StatusCode` is not accepted.
The branch is a new history on top of master (the first version
conflicted); master with #4674 is merged in.

# Description

The REST binding implements the routes of the OPC Foundation OpenAPI
mapping (OPC 10000-6 §G.3), but it does not describe them: `GET
/openapi.json` is answered with HTTP 405, and a client generator has
nothing to read from the server. `docs/WebApi.md` listed a generated
OpenAPI document as a deferred follow-up.

The coded API is the source of truth, so this PR **generates** the
document from the route table and from the structure definitions of the
request and response types, and compares it with the document the model
compiler publishes in tests. Nothing from `UA-Nodeset/OpenApi` ships in
the package.

## Changes

### Service sets (`Opc.Ua.Core`)

- `WebApiServiceSet` (`AllServices`, `Sessionless`) and
`WebApiServiceRoutes.GetRoutes(serviceSet)`. `Sessionless` is the eight
services of `opc.ua.openapi.sessionless.json` (OPC 10000-4 §6.3): Read,
Write, HistoryRead, HistoryUpdate, Call, Browse, BrowseNext,
TranslateBrowsePathsToNodeIds.

### Generator (`Opc.Ua.Core.Schema`, `Opc.Ua.Schema.OpenApi`)

- `WebApiOpenApiGenerator.Generate(serviceSet, includeSchemas,
serverUrl)` returns the OpenAPI 3.0 document as a `JsonObject`. It is
built at runtime from `WebApiServiceRoutes` and the
`StructureDefinition`/`EnumDefinition` of the message types (the same
definitions the schema generation uses, resolved through
`IDataTypeDefinitionResolver`). No reflection, so it is NativeAOT
compatible; the AOT test project covers it.
- **Two levels of detail**, because full schemas make big documents:

  | | Content | All 28 services |
  | --- | --- | --- |
| default | paths, `operationId`s, every body a JSON object | about 12
KB |
| `includeSchemas: true` | one component schema per message, structure
and enumeration (100), for typed client generators | about 46 KB |

  The two published files are about 300 KB together.
- The schemas describe the Compact JSON encoding, with the property
names, types, formats and integer ranges of the published documents.
DataValue is the one structure that differs: its status property is
`Status`, as in Part 6 Table 42.
- `OpenApiBuiltInSchemas` holds the schemas of the built-in types
(StatusCode, LocalizedText, Variant, DataValue, DiagnosticInfo,
ExtensionObject and the scalar types) as the encoder writes them.
Abstract `Structure` fields are ExtensionObjects, abstract number fields
are Variants.

### Serving the document (`Opc.Ua.Bindings.Https`)

- `WebApiTransportOptions`: `ServiceSet`, `OpenApiDocumentPath` (default
`null`: **off**) and `OpenApiIncludeSchemas` (default `false`).
- `MapWebApiEndpoints(WebApiTransportOptions)` maps the routes of the
service set and, when a path is set, the `GET` route of the document
**in the same route group**. The route has no `AllowAnonymous` metadata.
When an authentication scheme is registered, the contributor's
`group.RequireAuthorization()` covers the document like `POST /read`;
only `/findservers` and `/getendpoints` stay anonymous. The existing
`MapWebApiEndpoints()` maps all routes as before.
- The document is generated once per path base (listed as a relative
`servers` URL; without a path base the list is omitted) by the
`WebApiOpenApiGenerator` that `AddWebApiTransport` registers, or by a
default one.
- `Opc.Ua.Bindings.Https` references `Opc.Ua.Core.Schema` on net8.0 and
later.

### Documentation

- `docs/OpenApi.md` (new, linked from `docs/README.md`): serving the
document, the two levels, generating clients, the JSON generated clients
send, known issues, how the document is kept correct, troubleshooting.
- `docs/WebApi.md`: new section "Service sets and the OpenAPI document";
the deferred follow-up is removed. `docs/SchemaGeneration.md` and both
`NugetREADME.md` files describe the generator and the options.

## Comparison with the model compiler documents

The two published documents are test resources of
`Opc.Ua.Core.Schema.Tests` only (README next to them: source commit and
update procedure). `WebApiOpenApiConformanceTests` compares the
generated document with them for both service sets:

- paths, `operationId`s, and the request and response schema of every
operation;
- the set of component schemas the operations reach: equal (100 for all
services);
- every enumeration (members and values);
- for every structure: property names, types, formats, integer ranges,
and inheritance.

Everything both describe is equal. The test lists the differences and
fails when a listed one disappears or a new one appears:

| Difference | Generated | Published | Reason |
| --- | --- | --- | --- |
| DataValue status property | `Status` | `StatusCode` | Part 6 Table 42;
UA-Nodeset#146 is open. The stack only knows `Status` (encoder and
decoder). |
| `description`, `default` keywords | not written | spec links, .NET
defaults | documentation and defaults, not contract; Compact omits
default values |

`WebApiOpenApiWireFormatTests` validates what the binding really writes
(the default request and response of all 28 routes, plus populated
requests and responses with variants, status codes, references, identity
tokens and notifications) against the generated component schemas.

## Tests

- `Opc.Ua.Core.Schema.Tests` `OpenApi/`: `WebApiOpenApiGeneratorTests`
(shape of the document, both levels, both service sets, servers list,
sorting and determinism, concurrency, argument and resolver errors,
every built-in type, arrays and ranks, enumerations, option sets,
unions, base types, self-references, unknown definitions),
`WebApiOpenApiConformanceTests`, `WebApiOpenApiWireFormatTests`,
`OpenApiBuiltInSchemasTests`: 81 tests.
- `Opc.Ua.Bindings.Https.WebApi.Tests`:
`WebApiOpenApiDocumentEndpointTests` (TestServer with the startup
contributor: off by default, configured path, both levels, service set
maps and describes only the sessionless routes, path base, repeated
requests, registered generator is used, **a request without credentials
gets 401 when an authentication scheme is registered while one with
credentials gets 200, the route carries `IAuthorizeData` and no
`IAllowAnonymous`**, argument checks), options defaults and DI
registration of the generator.
- `Opc.Ua.Core.Tests`: `GetRoutes` for both sets and an undefined value.
- `Opc.Ua.Aot.Tests`: the generator and a served document under the AOT
fixture.
- Results (macOS arm64): `Opc.Ua.Core.Schema.Tests` 260/260,
`Opc.Ua.Bindings.Https.WebApi.Tests` 457/457, `Opc.Ua.Core.Tests` WebApi
tests 110/110, each on net10.0 and net8.0 (Release). `Opc.Ua.Aot.Tests`
(JIT run) SchemaAotTests 5/5, WebApiAotTests 8/8.
- `Opc.Ua.Core`, `Opc.Ua.Core.Schema` and `Opc.Ua.Bindings.Https` and
the three test projects build for net48, net8.0, net9.0 and net10.0
(Release) with 0 warnings and 0 errors (net48 builds only; the Windows
legs of the fork CI run its tests). `dotnet format` whitespace, style
and analyzers (`--severity info`) are clean on every changed file; the
two `RCS1090` hits in `SchemaAotTests.cs` are on lines that master
already has.
- Patch coverage with `.azurepipelines/check-coverage.ps1` against
master (`Opc.Ua.Core.Schema.Tests`, `Opc.Ua.Bindings.Https.WebApi.Tests`
and the WebApi tests of `Opc.Ua.Core.Tests`, net10.0): 362/362 changed
lines covered.
- Fork CI (full matrix incl. macOS) and CodeQL on `f990af5db` (master
with #4674 merged in): [CI run
37310622902](https://github.com/biancode/UA-.NETStandard/actions/runs/37310622902)
green, [CodeQL run
37310626786](https://github.com/biancode/UA-.NETStandard/actions/runs/37310626786)
green. The run on the earlier head `abda0e491` had one failure outside
this PR:
`McpServerProcessTests.HttpTransportAliasesExposeOnlyMcpRouteAsync("http")`
timed out after 30 s on Windows net10.0; this PR does not touch
`tools/`.

## Not in this PR

- Authentication: the fix discussed in the review is @romanett's #4674.
The document route uses whatever the REST routes use; this PR does not
change authentication.
- `StatusCode` tolerance in the decoder: dropped, the spec text is the
reference. The first commit of the previous version is gone.
- Samples.
- Session-less invocation on the server side (OPC 10000-4 §6.3) is a
separate draft PR. With `ServiceSet = Sessionless` this PR only limits
the mapped routes and the document.

## Questions

1. `Opc.Ua.Bindings.Https` now references `Opc.Ua.Core.Schema` (net8.0
and later) because the generator lives next to the other schema
generators and is trimmed away when unused. Fine, or should it move into
`Opc.Ua.Core`?
2. Should `OpenApiIncludeSchemas` default to `false` as here, or should
a host get typed clients out of the box?

## Related Issues

- Fixes #4656

## 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. (Affected
suites on net10.0 and net8.0 locally on macOS; .NET Framework is covered
by the fork CI's Windows net48 legs.)
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.
2026-10-06 09:43:28 +02:00