Drive the solution to zero warnings / zero errors with analyzers on,
promote the consistently-fixed rules to error, and lock in coverage
on the only line of new logic.
This change introduces two independent additions to the .NET Standard
stack:
## `Libraries/Opc.Ua.Server.FileSystem` (Part 5 §C / Part 20 §4)
Server-side implementation of the OPC UA `FileType` /
`FileDirectoryType` companion model, mirroring the existing client
namespace `Libraries/Opc.Ua.Client.FileSystem`.
### Provider abstraction
- `IFileSystemProvider` — async storage abstraction
(`GetEntryAsync` / `EnumerateAsync` / `OpenRead/WriteAsync` /
`Create{Directory,File}Async` / `DeleteAsync` / `MoveAsync` /
`CopyAsync`). All paths are forward-slash provider-relative; the
empty string is the root.
- `FileSystemEntry` record + `FileWriteMode` enum.
### Default `PhysicalFileSystemProvider`
`System.IO`-based implementation that mounts a **single physical
directory** as the FileSystem root. Rejects path-traversal attempts
(`..` escape) via `Path.GetFullPath` + root-prefix check. Supports
an optional `isWritable: false` mode for read-only mounts.
### Node manager
`FileSystemNodeManager` drives every Browse / Read / Method call
through the configured provider. Each mounted provider is anchored
as a `FileDirectoryType` instance under the standard
`Server.FileSystem` object (`ObjectIds.FileSystem`, `i=16314`)
via `HasComponent`, which is what
`FileSystemClient.OpenServerFileSystem` expects to find. Mount
multiple providers by registering multiple
`FileSystemNodeManager` instances. Companion files
(`DirectoryBrowser`, `DirectoryObjectState`, `FileObjectState`,
`FileHandle`, `FileSystemNodeId`, `FileSystemNodeManagerFactory`)
are all provider-driven.
### Client-side fix
`Libraries/Opc.Ua.Client.FileSystem.FileSystemClient.EnumerateChildrenAsync`
now stops the BrowseNext loop on `continuation.Length == 0` in
addition to `continuation.IsNull`. Without this fix, an
empty-but-non-null ByteString continuation returned by the SDK after
wire round-trip would cause a spurious BrowseNext and fail with
`BadContinuationPointInvalid`.
### Reference-server hook
`Quickstarts.ReferenceServer.ReferenceServer` gains two opt-in
properties (default off):
- `EnableFileSystemNodeManager` — toggles whether the FS node
manager is registered.
- `FileSystemProvider` — caller-supplied
`IFileSystemProvider`. When `null` and the flag is on, falls
back to a `PhysicalFileSystemProvider` rooted at
`%TEMP%/OpcUaReferenceServerFs` (mount name `Temp`).
### Tests
`Tests/Opc.Ua.Client.Tests/FileSystem/FileSystemClientIntegrationTests.cs`
— 12 end-to-end tests over a real
`ServerFixture<ReferenceServer>` + `ClientFixture` (opc.tcp,
SecurityNone, temp-dir provider): round-trip write/read,
enumeration, nested `CreateDirectory` / `CreateSubdirectory`,
delete, move, copy, large-file chunked read, mount BrowseName,
missing path returns null, multi-level enumeration, text round-trip,
read-only provider rejects write.
## `Libraries/Opc.Ua.Lds.Server`
A new Local Discovery Server (LDS) library implementing OPC UA Part
12 §7:
- `LdsServer` — main server class.
- `MulticastDiscovery` — DNS-SD / mDNS bootstrap via
`Makaretu.Dns.Multicast` (version 0.27.0 added to
`Directory.Packages.props`).
- `RegisteredServerStore` — in-memory store with TTL.
- `RegistrationEntry` + `ServerOnNetworkRecord` — value types.
Comes with a sample host `Applications/ConsoleLdsServer`.
## Build / test
- `dotnet build UA.slnx -c Release` -> 0 errors on all target
frameworks (net472, net48, netstandard2.1, net8.0, net9.0, net10.0).
- `Opc.Ua.Server.Tests` -> 964 pass, 5 skip, 0 fail.
- `FileSystemClientIntegrationTests` -> 12/12 pass.
Marc Schier