Seal [DataType] config classes and migrate remaining [DataContract] configs

[romanett]

Problem

AreaConfiguration (AlarmCondition server) is a non-sealed partial class. The source generator's default StructureHandling.Auto resolves to inline encoding only when the field's type is sealed and has no IEncodeable base — otherwise it wraps the value in an ExtensionObject to allow subtyping.

AreaConfiguration is the element type of two arrays, neither of which sets StructureHandling:

• AlarmConditionServerConfiguration.Areas
• AreaConfiguration.SubAreas (self-recursive)

So both were generated as WriteEncodeableArrayAsExtensionObjects / ReadEncodeableArrayAsExtensionObjects, while the shipped AlarmConditionServer.Config.xml stores plain nested <AreaConfiguration> elements with no ExtensionObject/TypeId wrappers.

The result was a silent failure — the area tree decoded as empty, no exception:

BEFORE  --- total areas decoded: 0 (expected 8) ---
AFTER   --- total areas decoded: 8 (expected 8) ---

Changes

Seal the 10 existing [DataType] types. AreaConfiguration, MemoryBufferInstance and PerformanceTestResultItem are used as property types, so only those change generated encoding. The rest are sealed for consistency, so the same bug cannot reappear when someone adds a nested property. None of these types is subclassed anywhere in the repo, so sealing is compile-safe.

Migrate the 9 remaining [DataContract] server configs to [DataType] sealed partial classes — Aggregation, Boiler, DataAccess, DataTypes, Empty, HistoricalEvents, Methods, PerfTest, SimpleEvents. The [OnDeserializing] Initialize(StreamingContext) hooks and now-unused System.Runtime.Serialization / System.ServiceModel usings are dropped, and the missing using Opc.Ua; added. The same residual scaffolding is cleaned from the already-migrated configs (Views, UserAuthentication, MemoryBuffer, TestData, HistoricalAccess).

Add the OPCFoundation.NetStandard.Opc.Ua.SourceGeneration analyzer reference to 9 projects. [DataType] without the analyzer generates nothing. Analyzers do not flow through ProjectReference, so nothing else supplied it. Note that HistoricalAccess Server already carried [DataType]/[DataTypeField] annotations that no generator ever acted on. No package version bump — the pinned 2.0.158.59919-preview already contains the sealed/StructureHandling support.

Re-enable ParseExtension<T> in nine node managers. These call sites had been stubbed to m_configuration = null; during the 2.0 migration, because ParseExtension<T> constrains T to IEncodeable, new() and the configs were plain [DataContract] POCOs. Now that they are source-generated IEncodeable types, the real call is restored in Boiler, DataAccess, DataTypes, Empty, HistoricalEvents, Methods, PerfTest, SimpleEvents and HistoricalAccess. The existing "use suitable defaults if no configuration exists" fallback is kept.

Two of those did not actually bind and needed their namespaces reconciled first. Both failed silently, falling back to defaults rather than erroring:

• HistoricalAccess used a bare [DataType], so its namespace defaulted to urn:quickstarts.historicalaccessserver, while the shipped config declares http://opcfoundation.org/Quickstarts/HistoricalAccess. This is the only one of the nine carrying real data, so ArchiveRoot silently stayed null instead of reading .\Archive. Now bound explicitly to Namespaces.HistoricalAccess.
• DataTypesServer.Config.xml declared xmlns="http://somecompany.com/DataTypes", which matches no constant in the project. Corrected to urn:localhost:somecompany.com:DataTypesServer — the value of Quickstarts.DataTypes.Namespaces.DataTypes and the server's own primary node namespace — making it consistent with the other eight samples.

Deliberately not changed

UA Sample Controls gets no analyzer reference. PerformanceTestResult is still actively round-tripped through DataContractSerializer in PerformanceTestDlg.LoadResults/SaveResults, and its TestCaseResults is a private List<T> rather than ArrayOf<T>. Only the sealing is applied there, and its live serializer hooks are left intact rather than reshaping unrelated UI sample code.

AggregationServerConfiguration keeps no ParseExtension call: it has no node manager field, no consumer, and no element in Quickstarts.AggregationServer.Config.xml, so there is nothing to restore. (AggregationServer.cs separately parses ConfiguredEndpointCollection, which is unaffected.)

Verification

• All touched projects build with 0 errors.
• Generated encoder for AlarmConditionServerConfiguration switched from WriteEncodeableArrayAsExtensionObjects to WriteEncodeableArray for both Areas and SubAreas; zero AsExtensionObject calls remain.
• Loading the real AlarmConditionServer.Config.xml through ParseExtension<AlarmConditionServerConfiguration>() decodes the full three-level tree (Green/Yellow → East/West → Red/Blue with 2 SourcePaths each) — 8 areas, versus 0 on master.
• Loading each of the nine shipped Config.xml files and calling ParseExtension<T> returns a bound IEncodeable instance in every case, and HistoricalAccess reads ArchiveRoot = ".\Archive":

Boiler             BOUND    ParseExtension<BoilerServerConfiguration> -> IEncodeable=True
DataAccess         BOUND    ParseExtension<DataAccessServerConfiguration> -> IEncodeable=True
DataTypes          BOUND    ParseExtension<DataTypesServerConfiguration> -> IEncodeable=True
Empty              BOUND    ParseExtension<EmptyServerConfiguration> -> IEncodeable=True
HistoricalEvents   BOUND    ParseExtension<HistoricalEventsServerConfiguration> -> IEncodeable=True
Methods            BOUND    ParseExtension<MethodsServerConfiguration> -> IEncodeable=True
PerfTest           BOUND    ParseExtension<PerfTestServerConfiguration> -> IEncodeable=True
SimpleEvents       BOUND    ParseExtension<SimpleEventsServerConfiguration> -> IEncodeable=True
HistoricalAccess   BOUND    ArchiveRoot = ".\Archive"

• Reverting either namespace fix reproduces the silent null on that sample, confirming both were required.

Note for reviewers

Eight of the nine migrated configs are empty (no fields), so restoring ParseExtension changes no observable behavior for them — it removes dead stubs and makes the samples demonstrate the intended pattern again. HistoricalAccess is the exception: it is a real behavior fix, since ArchiveRoot from the config file was previously being ignored.

🤖 Generated with Claude Code