feat(mtconnect): current/sample parse + sequence-gap detection (Task 7)
Adds the /current and /sample legs to MTConnectAgentClient: - MTConnectStreamsParser: hand-rolled System.Xml.Linq parse of an MTConnectStreams document into MTConnectStreamsResult. Observations are every element child of <Samples>/<Events>/<Condition>, keyed by dataItemId (the element NAME is the data item's type in PascalCase, so a fixed name set would drop observations). A CONDITION's value is its element name, not its text - <Normal/> is empty - and <Unavailable/> normalizes onto the same UNAVAILABLE sentinel a Sample/Event carries as text, so Task 8's no-comms mapping sees one token. Timestamps are normalized to DateTimeKind.Utc explicitly. - IsSequenceGap(requestedFrom, chunk) => chunk.FirstSequence > requestedFrom, so Task 11's pump can re-baseline after a ring-buffer overflow. Equality is NOT a gap. - SampleAsync: ResponseHeadersRead + a hand-rolled multipart/x-mixed-replace frame reader (Content-length fast path, boundary-scan fallback), bounded by a heartbeat watchdog derived from HeartbeatMs so a silent Agent faults instead of wedging the pump - the S7 frozen-peer shape (arch-review R2-01). The long poll gets its own HttpClient with an infinite Timeout so the unary /probe + /current deadline stays bounded. Task 0 package decision, option (c): both TrakHound PackageReferences and their PackageVersions are dropped. MTConnectHttpClientStream takes a URL and dials its own socket (no handler/stream seam, so it cannot serve a socket-free unit suite), and it emits already-parsed documents through the formatter lookup Task 6 proved is missing - framing-only reuse was never actually on offer. The driver now depends on nothing but the BCL. Recorded in the plan's Task 0 CORRECTION block. Also folds in two Task 6 review carry-overs: the stale IMTConnectAgentClient doc comment claiming a TrakHound-backed implementation, and a probe test constructing a mixed-namespace vendor extension (<x:Pump> with default-namespace <DataItems> children) that backs the parser's ignore-the-namespace claim with a test. 187/187 green.
This commit is contained in:
Joseph Doherty
@@ -9,8 +9,14 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
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/// canned probe/current/sample XML, with no sockets involved.
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/// </summary>
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/// <remarks>
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/// The production implementation (Task 6/7) is built on the TrakHound MTConnect.NET client
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/// libraries (Task 0's decision); a fake for tests only needs to implement these three members.
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/// The production implementation, <see cref="MTConnectAgentClient"/>, carries no backend NuGet
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/// at all: it is an <see cref="HttpClient"/> over the Agent's three request paths, feeding
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/// hand-rolled <c>System.Xml.Linq</c> parsers (<c>MTConnectProbeParser</c> /
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/// <c>MTConnectStreamsParser</c>) plus a <c>multipart/x-mixed-replace</c> frame reader for the
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/// <c>/sample</c> long poll. (Task 0 planned to build on the TrakHound MTConnect.NET libraries;
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/// Tasks 6 and 7 proved they can neither parse a document nor frame the stream socket-free, and
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/// dropped the references — see the Task 0 CORRECTION block in the plan.) A fake for tests only
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/// needs to implement these three members.
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/// </remarks>
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public interface IMTConnectAgentClient
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{
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@@ -1,3 +1,7 @@
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using System.Globalization;
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using System.Runtime.CompilerServices;
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using System.Text;
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namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
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/// <summary>
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@@ -8,19 +12,37 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
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/// <remarks>
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/// <para>
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/// <b>The constructor opens no connection.</b> It only composes the request URIs and builds
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/// an <see cref="HttpClient"/> (which itself dials nothing until a request is issued), so a
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/// throwaway instance is safe to construct — the universal discovery browser's
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/// <c>CanBrowse</c> pattern depends on that.
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/// its <see cref="HttpClient"/>s (which themselves dial nothing until a request is issued),
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/// so a throwaway instance is safe to construct — the universal discovery browser's
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/// <c>CanBrowse</c> pattern depends on that. <see cref="SampleAsync"/> likewise dials
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/// nothing until it is enumerated.
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/// </para>
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/// <para>
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/// <b>Every call is deadline-bounded.</b> Each request runs under a
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/// <see cref="CancellationTokenSource"/> linked to the caller's token and cancelled after
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/// <see cref="MTConnectDriverOptions.RequestTimeoutMs"/>, <i>and</i>
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/// <see cref="HttpClient.Timeout"/> is set to the same bound. A frozen Agent surfaces as a
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/// <see cref="TimeoutException"/> rather than wedging the caller — the lesson from this
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/// repo's S7 read-leg wall-clock gap (arch-review R2-01). A non-positive timeout is rejected
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/// at construction so an operator-authored <c>0</c> can never come to mean "wait forever"
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/// (arch-review 01/S-6).
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/// <b>Two <see cref="HttpClient"/>s, and the split is deliberate.</b>
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/// <see cref="HttpClient.Timeout"/> is a per-instance, whole-response deadline, so a single
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/// client cannot serve both legs: the unary <c>/probe</c> and <c>/current</c> calls must be
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/// bounded by <see cref="MTConnectDriverOptions.RequestTimeoutMs"/>, while <c>/sample</c> is
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/// a long poll that is <i>supposed</i> to outlive that bound indefinitely. Raising the one
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/// timeout to suit the stream would un-bound the unary deadline — precisely what arch-review
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/// R2-01 says must never happen — so the streaming leg gets its own client with
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/// <see cref="Timeout.InfiniteTimeSpan"/> and is bounded differently instead (below).
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/// </para>
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/// <para>
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/// <b>Every call is deadline-bounded, but not all by the same mechanism.</b> The unary legs
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/// run under a <see cref="CancellationTokenSource"/> linked to the caller's token and
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/// cancelled after <c>RequestTimeoutMs</c>. The streaming leg bounds its <i>header</i> phase
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/// the same way (a peer that accepts the connection and never answers must not wedge the
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/// pump), then hands the body to a <b>heartbeat watchdog</b>: MTConnect Agents emit a
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/// keep-alive chunk every <see cref="MTConnectDriverOptions.HeartbeatMs"/> precisely so a
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/// client can tell "quiet but alive" from "dead", so every body read is bounded by a
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/// two-missed-heartbeat window and a silent Agent surfaces as a
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/// <see cref="TimeoutException"/>. This is the exact shape of this repo's S7 frozen-peer
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/// production defect (arch-review R2-01) — an async read that ignores the socket deadline —
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/// and the watchdog is what closes it here.
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/// </para>
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/// <para>
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/// A non-positive <c>RequestTimeoutMs</c> is rejected at construction so an
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/// operator-authored <c>0</c> can never come to mean "wait forever" (arch-review 01/S-6).
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/// </para>
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/// <para>
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/// This class does not swallow failures into an empty model: an unreachable Agent, a non-2xx
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@@ -31,8 +53,13 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
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public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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{
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private readonly HttpClient _http;
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private readonly HttpClient _streamHttp;
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private readonly Uri _probeUri;
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private readonly Uri _currentUri;
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private readonly string _sampleUriBase;
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private readonly string _sampleQuerySuffix;
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private readonly TimeSpan _requestTimeout;
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private readonly TimeSpan _streamIdleTimeout;
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/// <summary>Creates a client for the Agent described by <paramref name="options"/>.</summary>
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/// <param name="options">The driver options carrying the Agent URI, device scope, and per-call deadline.</param>
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@@ -61,10 +88,50 @@ public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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}
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_requestTimeout = TimeSpan.FromMilliseconds(options.RequestTimeoutMs);
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// Two missed heartbeats plus one request timeout of network slack. Deriving the window from
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// HeartbeatMs is what makes it a liveness check rather than a throughput assumption: a busy
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// Agent and an idle one both emit at least one chunk per heartbeat. A non-positive
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// HeartbeatMs is clamped away rather than rejected — the window then collapses to
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// RequestTimeoutMs, which is still strictly positive, so the read can never be unbounded.
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_streamIdleTimeout = TimeSpan.FromMilliseconds(
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(2L * Math.Max(0, options.HeartbeatMs)) + options.RequestTimeoutMs);
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_probeUri = BuildRequestUri(options, "probe");
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_currentUri = BuildRequestUri(options, "current");
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_sampleUriBase = BuildRequestUri(options, "sample").AbsoluteUri;
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_sampleQuerySuffix = string.Create(
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CultureInfo.InvariantCulture,
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$"&interval={options.SampleIntervalMs}&count={options.SampleCount}&heartbeat={options.HeartbeatMs}");
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_http = handler is null ? new HttpClient() : new HttpClient(handler, disposeHandler: false);
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_http.Timeout = _requestTimeout;
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_streamHttp = handler is null ? new HttpClient() : new HttpClient(handler, disposeHandler: false);
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// See the class remarks: a long poll must outlive the unary deadline by design, and the
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// heartbeat watchdog — not this property — is what keeps it bounded.
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_streamHttp.Timeout = Timeout.InfiniteTimeSpan;
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}
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/// <summary>
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/// Has the Agent's ring buffer overflowed past what the caller asked for? True when the
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/// chunk's oldest retained sequence is <i>strictly</i> newer than the sequence the caller
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/// requested, which means observations between the two were evicted before the caller could
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/// read them. Equality is not a gap: <c>firstSequence == requestedFrom</c> is the ordinary
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/// contiguous case where the Agent simply had nothing older to send.
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/// </summary>
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/// <param name="requestedFrom">The <c>from</c> sequence the caller passed to <see cref="SampleAsync"/>.</param>
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/// <param name="chunk">The chunk the Agent answered with.</param>
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/// <returns>
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/// <c>true</c> when observations were lost and the caller must re-baseline via
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/// <see cref="CurrentAsync"/> rather than trusting an incremental update.
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/// </returns>
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public static bool IsSequenceGap(long requestedFrom, MTConnectStreamsResult chunk)
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{
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ArgumentNullException.ThrowIfNull(chunk);
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return chunk.FirstSequence > requestedFrom;
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}
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/// <inheritdoc/>
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@@ -80,18 +147,73 @@ public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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}
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/// <inheritdoc/>
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public Task<MTConnectStreamsResult> CurrentAsync(CancellationToken ct) =>
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// Task 7 adds the /current leg (MTConnectStreamsParser); deliberately not stubbed as an
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// empty result, which would read as a working call that silently returns nothing.
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throw new NotImplementedException("The MTConnect /current leg lands in Task 7.");
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public async Task<MTConnectStreamsResult> CurrentAsync(CancellationToken ct)
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{
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using var response = await SendAsync(_currentUri, ct).ConfigureAwait(false);
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await using var body = await response.Content.ReadAsStreamAsync(ct).ConfigureAwait(false);
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return MTConnectStreamsParser.Parse(body);
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}
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/// <inheritdoc/>
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public IAsyncEnumerable<MTConnectStreamsResult> SampleAsync(long from, CancellationToken ct) =>
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// Task 7 adds the /sample long-poll leg (multipart chunk framing + sequence-gap detection).
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throw new NotImplementedException("The MTConnect /sample leg lands in Task 7.");
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public async IAsyncEnumerable<MTConnectStreamsResult> SampleAsync(
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long from,
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[EnumeratorCancellation] CancellationToken ct)
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{
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var uri = BuildSampleUri(from);
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using var request = new HttpRequestMessage(HttpMethod.Get, uri);
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// ResponseHeadersRead, not the default ResponseContentRead: buffering a
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// multipart/x-mixed-replace body that is designed never to end would hang here forever.
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using var response = await SendStreamRequestAsync(request, uri, ct).ConfigureAwait(false);
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await using var body = await response.Content.ReadAsStreamAsync(ct).ConfigureAwait(false);
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var boundary = ResolveMultipartBoundary(response);
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if (boundary is null)
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{
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// Not a multipart stream: the Agent answered with a single document. This is the shape
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// an MTConnectError takes — Agents serve one under HTTP 200 — so the parse below is what
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// surfaces the Agent's own error text rather than an empty, successful-looking stream.
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yield return MTConnectStreamsParser.Parse(await ReadWholeBodyAsync(body, uri, ct).ConfigureAwait(false));
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yield break;
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}
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var reader = new MultipartStreamReader(body, boundary, _streamIdleTimeout, uri);
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while (true)
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{
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var part = await reader.ReadNextPartAsync(ct).ConfigureAwait(false);
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if (part is null)
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{
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yield break;
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}
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// A frame carrying nothing but whitespace is transport filler, not a document. The
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// Agent's real keep-alive is a well-formed observation-free MTConnectStreams document,
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// and that one IS yielded — it advances the sequence, so swallowing it would strand the
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// caller's `from` behind the Agent's buffer.
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if (string.IsNullOrWhiteSpace(part))
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{
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continue;
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}
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yield return MTConnectStreamsParser.Parse(part);
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}
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}
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/// <inheritdoc/>
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public void Dispose() => _http.Dispose();
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public void Dispose()
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{
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_http.Dispose();
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_streamHttp.Dispose();
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}
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private Uri BuildSampleUri(long from) =>
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new(string.Create(CultureInfo.InvariantCulture, $"{_sampleUriBase}?from={from}{_sampleQuerySuffix}"),
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UriKind.Absolute);
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private async Task<HttpResponseMessage> SendAsync(Uri uri, CancellationToken ct)
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{
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@@ -108,8 +230,7 @@ public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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// The caller did not cancel, so this is our own deadline (or HttpClient.Timeout) firing.
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// Reported as a TimeoutException because a bare "A task was canceled" tells an operator
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// nothing about which Agent stopped answering.
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throw new TimeoutException(
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$"MTConnect Agent request to '{uri}' did not complete within {_requestTimeout.TotalMilliseconds:F0} ms.");
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throw TimedOut(uri);
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}
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response.EnsureSuccessStatusCode();
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@@ -117,6 +238,73 @@ public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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return response;
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}
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/// <summary>
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/// Issues the <c>/sample</c> request and returns as soon as the response headers land. Only
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/// this phase is bounded by the unary deadline; the body is bounded by the watchdog.
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/// </summary>
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private async Task<HttpResponseMessage> SendStreamRequestAsync(
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HttpRequestMessage request, Uri uri, CancellationToken ct)
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{
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using var deadline = CancellationTokenSource.CreateLinkedTokenSource(ct);
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deadline.CancelAfter(_requestTimeout);
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HttpResponseMessage response;
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try
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{
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response = await _streamHttp
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.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, deadline.Token)
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.ConfigureAwait(false);
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}
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catch (OperationCanceledException) when (!ct.IsCancellationRequested)
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{
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throw TimedOut(uri);
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}
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response.EnsureSuccessStatusCode();
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return response;
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}
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/// <summary>Reads a non-multipart streaming body whole, under the unary deadline.</summary>
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private async Task<string> ReadWholeBodyAsync(Stream body, Uri uri, CancellationToken ct)
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{
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using var deadline = CancellationTokenSource.CreateLinkedTokenSource(ct);
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deadline.CancelAfter(_requestTimeout);
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using var reader = new StreamReader(body, Encoding.UTF8);
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try
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{
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return await reader.ReadToEndAsync(deadline.Token).ConfigureAwait(false);
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}
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catch (OperationCanceledException) when (!ct.IsCancellationRequested)
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{
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throw TimedOut(uri);
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}
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}
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private TimeoutException TimedOut(Uri uri) =>
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new($"MTConnect Agent request to '{uri}' did not complete within {_requestTimeout.TotalMilliseconds:F0} ms.");
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/// <summary>
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/// The <c>boundary</c> parameter of a <c>multipart/*</c> response, or <c>null</c> when the
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/// Agent answered with a single (non-multipart) document.
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/// </summary>
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private static string? ResolveMultipartBoundary(HttpResponseMessage response)
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{
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var contentType = response.Content.Headers.ContentType;
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if (contentType?.MediaType is null ||
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!contentType.MediaType.StartsWith("multipart/", StringComparison.OrdinalIgnoreCase))
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{
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return null;
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}
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var boundary = contentType.Parameters
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.FirstOrDefault(p => string.Equals(p.Name, "boundary", StringComparison.OrdinalIgnoreCase))?.Value?
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.Trim('"');
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return string.IsNullOrEmpty(boundary) ? null : boundary;
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}
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private static Uri BuildRequestUri(MTConnectDriverOptions options, string request)
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{
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var agentUri = options.AgentUri?.Trim();
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@@ -139,4 +327,291 @@ public sealed class MTConnectAgentClient : IMTConnectAgentClient, IDisposable
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return new Uri($"{root}{deviceSegment}/{request}", UriKind.Absolute);
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}
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/// <summary>
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/// Frames a <c>multipart/x-mixed-replace</c> body into individual part payloads, reading
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/// incrementally and never buffering more than the part currently in flight.
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/// </summary>
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/// <remarks>
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/// <para>
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/// <b>Why hand-rolled.</b> ASP.NET Core's <c>MultipartReader</c> is not in this
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/// dependency set, and TrakHound's
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/// <c>MTConnectHttpClientStream</c> — the one candidate the plan left open — takes a URL
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/// and dials its own socket, so it can neither be fed an existing response stream nor be
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/// exercised without a listener. See the Task 0 correction in the plan.
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/// </para>
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/// <para>
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/// <b>Two framing paths, and the first one matters for latency.</b> When the part carries
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/// a <c>Content-length</c> header — every Agent in the wild writes one — the body is read
|
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/// by length and the chunk is emitted the instant it is complete. Without it there is no
|
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/// way to know a part has ended except by seeing the <i>next</i> boundary, so that path
|
||||
/// necessarily emits each chunk one chunk late; it exists as a correctness fallback, not
|
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/// as the expected path.
|
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/// </para>
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||||
/// <para>
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||||
/// <b>Every read is watchdog-bounded.</b> A silent peer faults the stream rather than
|
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/// parking a task forever (arch-review R2-01), and the buffer is capped so a hostile or
|
||||
/// malfunctioning Agent cannot grow it without limit.
|
||||
/// </para>
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||||
/// </remarks>
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private sealed class MultipartStreamReader(Stream stream, string boundary, TimeSpan idleTimeout, Uri uri)
|
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{
|
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private const int MaxBufferBytes = 32 * 1024 * 1024;
|
||||
|
||||
private static readonly byte[] CrLfCrLf = "\r\n\r\n"u8.ToArray();
|
||||
private static readonly byte[] LfLf = "\n\n"u8.ToArray();
|
||||
|
||||
private readonly byte[] _delimiter = Encoding.ASCII.GetBytes("--" + boundary);
|
||||
private byte[] _buffer = new byte[16 * 1024];
|
||||
private int _length;
|
||||
private bool _finished;
|
||||
|
||||
/// <summary>
|
||||
/// Reads the next part's payload, or <c>null</c> once the closing delimiter is seen or
|
||||
/// the Agent closes the connection.
|
||||
/// </summary>
|
||||
public async Task<string?> ReadNextPartAsync(CancellationToken ct)
|
||||
{
|
||||
if (_finished)
|
||||
{
|
||||
return null;
|
||||
}
|
||||
|
||||
if (!await SkipThroughDelimiterAsync(ct).ConfigureAwait(false) ||
|
||||
!await EnsureAsync(2, ct).ConfigureAwait(false))
|
||||
{
|
||||
_finished = true;
|
||||
|
||||
return null;
|
||||
}
|
||||
|
||||
// "--boundary--" closes the stream.
|
||||
if (_buffer[0] == (byte)'-' && _buffer[1] == (byte)'-')
|
||||
{
|
||||
_finished = true;
|
||||
|
||||
return null;
|
||||
}
|
||||
|
||||
var headerEnd = await FindHeaderEndAsync(ct).ConfigureAwait(false);
|
||||
if (headerEnd < 0)
|
||||
{
|
||||
_finished = true;
|
||||
|
||||
return null;
|
||||
}
|
||||
|
||||
var headers = Encoding.ASCII.GetString(_buffer, 0, headerEnd);
|
||||
Consume(headerEnd);
|
||||
|
||||
var body = ParseContentLength(headers) is { } declared
|
||||
? await ReadByLengthAsync(declared, ct).ConfigureAwait(false)
|
||||
: await ReadToNextDelimiterAsync(ct).ConfigureAwait(false);
|
||||
|
||||
return body is null ? null : Encoding.UTF8.GetString(body);
|
||||
}
|
||||
|
||||
private async Task<byte[]?> ReadByLengthAsync(int declared, CancellationToken ct)
|
||||
{
|
||||
if (!await EnsureAsync(declared, ct).ConfigureAwait(false))
|
||||
{
|
||||
_finished = true;
|
||||
|
||||
return null;
|
||||
}
|
||||
|
||||
var body = _buffer[..declared];
|
||||
Consume(declared);
|
||||
|
||||
return body;
|
||||
}
|
||||
|
||||
private async Task<byte[]?> ReadToNextDelimiterAsync(CancellationToken ct)
|
||||
{
|
||||
var next = await FindDelimiterAsync(ct).ConfigureAwait(false);
|
||||
if (next < 0)
|
||||
{
|
||||
// EOF with no closing delimiter: whatever is buffered is the last part.
|
||||
var tail = _buffer[.._length];
|
||||
_length = 0;
|
||||
_finished = true;
|
||||
|
||||
return tail;
|
||||
}
|
||||
|
||||
var body = _buffer[..TrimTrailingLineBreak(next)];
|
||||
|
||||
// Leave the delimiter itself in place; the next call's skip consumes it.
|
||||
Consume(next);
|
||||
|
||||
return body;
|
||||
}
|
||||
|
||||
/// <summary>Strips the single line break that terminates a part body before its delimiter.</summary>
|
||||
private int TrimTrailingLineBreak(int end)
|
||||
{
|
||||
if (end >= 2 && _buffer[end - 2] == (byte)'\r' && _buffer[end - 1] == (byte)'\n')
|
||||
{
|
||||
return end - 2;
|
||||
}
|
||||
|
||||
return end >= 1 && _buffer[end - 1] == (byte)'\n' ? end - 1 : end;
|
||||
}
|
||||
|
||||
/// <summary>Advances past the next boundary delimiter; <c>false</c> at end of stream.</summary>
|
||||
private async Task<bool> SkipThroughDelimiterAsync(CancellationToken ct)
|
||||
{
|
||||
var index = await FindDelimiterAsync(ct).ConfigureAwait(false);
|
||||
if (index < 0)
|
||||
{
|
||||
return false;
|
||||
}
|
||||
|
||||
Consume(index + _delimiter.Length);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
private async Task<int> FindDelimiterAsync(CancellationToken ct)
|
||||
{
|
||||
var searchedTo = 0;
|
||||
while (true)
|
||||
{
|
||||
var index = IndexOf(_delimiter, Math.Max(0, searchedTo - (_delimiter.Length - 1)));
|
||||
if (index >= 0)
|
||||
{
|
||||
return index;
|
||||
}
|
||||
|
||||
searchedTo = _length;
|
||||
if (!await FillAsync(ct).ConfigureAwait(false))
|
||||
{
|
||||
return -1;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Finds the end of the part's header block — the first blank line after the delimiter.
|
||||
/// A part with no headers at all is legal, in which case the blank line sits at offset 0.
|
||||
/// </summary>
|
||||
private async Task<int> FindHeaderEndAsync(CancellationToken ct)
|
||||
{
|
||||
var searchedTo = 0;
|
||||
while (true)
|
||||
{
|
||||
var crlf = IndexOf(CrLfCrLf, Math.Max(0, searchedTo - 3));
|
||||
var lf = IndexOf(LfLf, Math.Max(0, searchedTo - 1));
|
||||
|
||||
if (crlf >= 0 && (lf < 0 || crlf <= lf))
|
||||
{
|
||||
return crlf + CrLfCrLf.Length;
|
||||
}
|
||||
|
||||
if (lf >= 0)
|
||||
{
|
||||
return lf + LfLf.Length;
|
||||
}
|
||||
|
||||
searchedTo = _length;
|
||||
if (!await FillAsync(ct).ConfigureAwait(false))
|
||||
{
|
||||
return -1;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
private static int? ParseContentLength(string headers)
|
||||
{
|
||||
foreach (var line in headers.Split('\n'))
|
||||
{
|
||||
var trimmed = line.Trim();
|
||||
if (!trimmed.StartsWith("content-length:", StringComparison.OrdinalIgnoreCase))
|
||||
{
|
||||
continue;
|
||||
}
|
||||
|
||||
var raw = trimmed["content-length:".Length..].Trim();
|
||||
|
||||
return int.TryParse(raw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var value) &&
|
||||
value >= 0
|
||||
? value
|
||||
: null;
|
||||
}
|
||||
|
||||
return null;
|
||||
}
|
||||
|
||||
private async Task<bool> EnsureAsync(int count, CancellationToken ct)
|
||||
{
|
||||
while (_length < count)
|
||||
{
|
||||
if (!await FillAsync(ct).ConfigureAwait(false))
|
||||
{
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Reads at least one more byte, bounded by the heartbeat watchdog. Returns <c>false</c>
|
||||
/// at end of stream and throws <see cref="TimeoutException"/> when the Agent goes silent.
|
||||
/// </summary>
|
||||
private async Task<bool> FillAsync(CancellationToken ct)
|
||||
{
|
||||
if (_length == _buffer.Length)
|
||||
{
|
||||
if (_buffer.Length >= MaxBufferBytes)
|
||||
{
|
||||
throw new InvalidDataException(
|
||||
$"MTConnect /sample stream from '{uri}' sent a part larger than {MaxBufferBytes} bytes without a boundary; refusing to buffer further.");
|
||||
}
|
||||
|
||||
Array.Resize(ref _buffer, Math.Min(_buffer.Length * 2, MaxBufferBytes));
|
||||
}
|
||||
|
||||
using var watchdog = CancellationTokenSource.CreateLinkedTokenSource(ct);
|
||||
watchdog.CancelAfter(idleTimeout);
|
||||
|
||||
int read;
|
||||
try
|
||||
{
|
||||
read = await stream.ReadAsync(_buffer.AsMemory(_length), watchdog.Token).ConfigureAwait(false);
|
||||
}
|
||||
catch (OperationCanceledException) when (!ct.IsCancellationRequested)
|
||||
{
|
||||
throw new TimeoutException(
|
||||
$"MTConnect /sample stream from '{uri}' sent no data (not even a heartbeat) within {idleTimeout.TotalMilliseconds:F0} ms; treating the Agent as unreachable rather than waiting indefinitely.");
|
||||
}
|
||||
|
||||
if (read <= 0)
|
||||
{
|
||||
return false;
|
||||
}
|
||||
|
||||
_length += read;
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
private int IndexOf(byte[] pattern, int start)
|
||||
{
|
||||
if (start >= _length)
|
||||
{
|
||||
return -1;
|
||||
}
|
||||
|
||||
var index = _buffer.AsSpan(start, _length - start).IndexOf(pattern.AsSpan());
|
||||
|
||||
return index < 0 ? -1 : index + start;
|
||||
}
|
||||
|
||||
private void Consume(int count)
|
||||
{
|
||||
Buffer.BlockCopy(_buffer, count, _buffer, 0, _length - count);
|
||||
_length -= count;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@@ -11,8 +11,8 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
|
||||
/// </summary>
|
||||
/// <remarks>
|
||||
/// <para>
|
||||
/// <b>Why hand-rolled rather than TrakHound.</b> The referenced TrakHound packages
|
||||
/// (<c>MTConnect.NET-Common</c> + <c>-HTTP</c> 6.9.0.2) contain <b>no</b>
|
||||
/// <b>Why hand-rolled rather than TrakHound.</b> The TrakHound packages Task 0 pinned
|
||||
/// (<c>MTConnect.NET-Common</c> + <c>-HTTP</c> 6.9.0.2 — both dropped in Task 7) contain <b>no</b>
|
||||
/// <c>IResponseDocumentFormatter</c> implementation — the XML formatter ships in the
|
||||
/// separate, unreferenced <c>MTConnect.NET-XML</c> package — so
|
||||
/// <c>ResponseDocumentFormatter.CreateDevicesResponseDocument("xml", stream)</c> answers
|
||||
|
||||
@@ -0,0 +1,296 @@
|
||||
using System.Globalization;
|
||||
using System.Xml;
|
||||
using System.Xml.Linq;
|
||||
|
||||
namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
|
||||
|
||||
/// <summary>
|
||||
/// Turns an MTConnect Agent <c>MTConnectStreams</c> document — a <c>/current</c> snapshot or one
|
||||
/// chunk of a <c>/sample</c> multipart stream — into the neutral
|
||||
/// <see cref="MTConnectStreamsResult"/>. Deliberately a pure, socket-free static so the whole
|
||||
/// parse is unit-testable against canned fixtures; chunk framing lives in
|
||||
/// <see cref="MTConnectAgentClient"/> and hands this parser one chunk's XML at a time.
|
||||
/// </summary>
|
||||
/// <remarks>
|
||||
/// <para>
|
||||
/// <b>Why hand-rolled rather than TrakHound.</b> Same finding as
|
||||
/// <see cref="MTConnectProbeParser"/>: the packages pinned by Task 0 ship no XML document
|
||||
/// formatter, and TrakHound's streaming client offers no socket-free entry point. Both
|
||||
/// package references were dropped in Task 7; the driver depends only on the BCL.
|
||||
/// </para>
|
||||
/// <para>
|
||||
/// <b>The Streams document is shaped nothing like the Devices document</b>, and three
|
||||
/// differences drive this parser's design.
|
||||
/// </para>
|
||||
/// <list type="number">
|
||||
/// <item>
|
||||
/// <description>
|
||||
/// <b>The observation element's name is the data item's type in PascalCase</b>
|
||||
/// (<c>Position</c>, <c>PartCount</c>, <c>Execution</c>) — not the probe's
|
||||
/// UPPER_SNAKE <c>POSITION</c> / <c>PART_COUNT</c>. The standard defines hundreds of
|
||||
/// types and vendors add more, so matching a fixed set of element names would drop
|
||||
/// observations silently. <b>Every</b> element child of <c><Samples></c>,
|
||||
/// <c><Events></c> and <c><Condition></c> is therefore an observation,
|
||||
/// keyed by its <c>dataItemId</c> attribute — the only identity the probe model and
|
||||
/// the streams document actually share.
|
||||
/// </description>
|
||||
/// </item>
|
||||
/// <item>
|
||||
/// <description>
|
||||
/// <b>A CONDITION observation's value is its ELEMENT NAME, not its text.</b>
|
||||
/// <c><Normal/></c> / <c><Warning/></c> / <c><Fault/></c> /
|
||||
/// <c><Unavailable/></c> carry the state in the name and are typically empty;
|
||||
/// where text is present it is the operator-facing message, not the state. Reading
|
||||
/// the text would report every condition as an empty string.
|
||||
/// <c><Unavailable/></c> is normalized to the literal
|
||||
/// <see cref="UnavailableSentinel"/> so a no-comms condition lands on exactly the
|
||||
/// same sentinel as a Sample/Event whose text is <c>UNAVAILABLE</c> — the
|
||||
/// observation index maps that one token to bad quality.
|
||||
/// </description>
|
||||
/// </item>
|
||||
/// <item>
|
||||
/// <description>
|
||||
/// <b>Timestamps are normalized to UTC explicitly.</b> MTConnect timestamps are
|
||||
/// ISO-8601 Zulu, but a bare <c>DateTime.Parse</c> yields <c>Local</c> or
|
||||
/// <c>Unspecified</c> depending on machine settings — and this value becomes the
|
||||
/// OPC UA SourceTimestamp, so a wrong <see cref="DateTimeKind"/> shifts every
|
||||
/// timestamp by the host's UTC offset with nothing to show for it.
|
||||
/// </description>
|
||||
/// </item>
|
||||
/// </list>
|
||||
/// <para>
|
||||
/// <b>Failure posture.</b> A malformed document, a non-<c>MTConnectStreams</c> root (an Agent
|
||||
/// <c>MTConnectError</c> served under HTTP 200 included), an unusable header, or an
|
||||
/// observation missing its <c>dataItemId</c>/<c>timestamp</c> all throw
|
||||
/// <see cref="InvalidDataException"/>. A document with a valid header and <i>zero</i>
|
||||
/// observations, by contrast, is entirely legal — <c>/sample</c> chunks are deltas and an
|
||||
/// idle Agent's keep-alive is an observation-free document — so it parses to an empty
|
||||
/// observation list rather than throwing.
|
||||
/// </para>
|
||||
/// </remarks>
|
||||
internal static class MTConnectStreamsParser
|
||||
{
|
||||
/// <summary>
|
||||
/// The single token that means "the Agent has no value for this data item". Sample/Event
|
||||
/// observations carry it as text; a CONDITION carries it as the element name
|
||||
/// <c><Unavailable/></c> and is normalized onto this spelling here.
|
||||
/// </summary>
|
||||
private const string UnavailableSentinel = "UNAVAILABLE";
|
||||
|
||||
private const string ConditionContainer = "Condition";
|
||||
|
||||
/// <summary>
|
||||
/// The three elements whose element children are observations. A ComponentStream may carry
|
||||
/// any subset of them, including none.
|
||||
/// </summary>
|
||||
private static readonly string[] ObservationContainers = ["Samples", "Events", ConditionContainer];
|
||||
|
||||
/// <summary>Parses a <c>/current</c> response, or one <c>/sample</c> chunk, held as a string.</summary>
|
||||
/// <param name="xml">The raw <c>MTConnectStreams</c> XML document.</param>
|
||||
/// <exception cref="InvalidDataException">
|
||||
/// The payload is empty, not well-formed XML, not an <c>MTConnectStreams</c> document (an
|
||||
/// Agent <c>MTConnectError</c> included — Agents answer a bad request with one under HTTP
|
||||
/// 200), carries no usable <c><Header></c>, or carries a malformed observation.
|
||||
/// </exception>
|
||||
public static MTConnectStreamsResult Parse(string xml)
|
||||
{
|
||||
if (string.IsNullOrWhiteSpace(xml))
|
||||
{
|
||||
throw new InvalidDataException(
|
||||
"MTConnect streams response was empty; expected an MTConnectStreams XML document.");
|
||||
}
|
||||
|
||||
XDocument document;
|
||||
try
|
||||
{
|
||||
// A chunk lifted out of a multipart frame can carry a byte-order mark or the framing's
|
||||
// trailing line break; XmlReader rejects either ahead of the XML declaration.
|
||||
document = XDocument.Parse(xml.Trim('', ' ', '\t', '\r', '\n'));
|
||||
}
|
||||
catch (XmlException ex)
|
||||
{
|
||||
throw new InvalidDataException($"MTConnect streams response is not well-formed XML: {ex.Message}", ex);
|
||||
}
|
||||
|
||||
return Build(document);
|
||||
}
|
||||
|
||||
/// <summary>Parses a <c>/current</c> response read from a stream.</summary>
|
||||
/// <param name="stream">A stream positioned at the start of the XML document.</param>
|
||||
/// <exception cref="InvalidDataException">As for <see cref="Parse(string)"/>.</exception>
|
||||
public static MTConnectStreamsResult Parse(Stream stream)
|
||||
{
|
||||
ArgumentNullException.ThrowIfNull(stream);
|
||||
|
||||
XDocument document;
|
||||
try
|
||||
{
|
||||
document = XDocument.Load(stream);
|
||||
}
|
||||
catch (XmlException ex)
|
||||
{
|
||||
throw new InvalidDataException($"MTConnect streams response is not well-formed XML: {ex.Message}", ex);
|
||||
}
|
||||
|
||||
return Build(document);
|
||||
}
|
||||
|
||||
private static MTConnectStreamsResult Build(XDocument document)
|
||||
{
|
||||
var root = document.Root
|
||||
?? throw new InvalidDataException("MTConnect streams response has no root element.");
|
||||
|
||||
if (!IsNamed(root, "MTConnectStreams"))
|
||||
{
|
||||
throw new InvalidDataException(DescribeUnexpectedRoot(root));
|
||||
}
|
||||
|
||||
var header = ChildrenNamed(root, "Header").FirstOrDefault()
|
||||
?? throw new InvalidDataException(
|
||||
"MTConnect streams response has no <Header>; without it the sequence bookkeeping the sample pump runs on is unknowable.");
|
||||
|
||||
return new MTConnectStreamsResult(
|
||||
RequiredLongAttribute(header, "instanceId"),
|
||||
RequiredLongAttribute(header, "nextSequence"),
|
||||
RequiredLongAttribute(header, "firstSequence"),
|
||||
ReadObservations(root));
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Collects every observation in the document, in Agent-supplied order. Containers are found
|
||||
/// by descending the whole <c><Streams></c> subtree rather than by walking a fixed
|
||||
/// DeviceStream → ComponentStream chain, so a vendor's extra nesting level cannot silently
|
||||
/// hide a device's observations.
|
||||
/// </summary>
|
||||
private static IReadOnlyList<MTConnectObservation> ReadObservations(XElement root)
|
||||
{
|
||||
var observations = new List<MTConnectObservation>();
|
||||
|
||||
foreach (var container in root.Descendants().Where(IsObservationContainer))
|
||||
{
|
||||
var isCondition = IsNamed(container, ConditionContainer);
|
||||
foreach (var element in container.Elements())
|
||||
{
|
||||
observations.Add(ReadObservation(element, isCondition));
|
||||
}
|
||||
}
|
||||
|
||||
return observations;
|
||||
}
|
||||
|
||||
private static MTConnectObservation ReadObservation(XElement element, bool isCondition)
|
||||
{
|
||||
var dataItemId = RequiredAttribute(element, "dataItemId", $"Observation <{element.Name.LocalName}>");
|
||||
|
||||
return new MTConnectObservation(
|
||||
dataItemId,
|
||||
isCondition ? ConditionState(element) : element.Value.Trim(),
|
||||
ReadTimestampUtc(element, dataItemId));
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// A condition's state is its element name. <c>Unavailable</c> is normalized to the
|
||||
/// <see cref="UnavailableSentinel"/> spelling so downstream quality mapping has exactly one
|
||||
/// token to recognize; every other state is reported as-named (<c>Normal</c>, <c>Warning</c>,
|
||||
/// <c>Fault</c>, and any vendor state).
|
||||
/// </summary>
|
||||
private static string ConditionState(XElement element)
|
||||
{
|
||||
var state = element.Name.LocalName;
|
||||
|
||||
return string.Equals(state, "Unavailable", StringComparison.OrdinalIgnoreCase) ? UnavailableSentinel : state;
|
||||
}
|
||||
|
||||
private static DateTime ReadTimestampUtc(XElement element, string dataItemId)
|
||||
{
|
||||
var raw = RequiredAttribute(element, "timestamp", $"Observation '{dataItemId}'");
|
||||
|
||||
if (!DateTime.TryParse(
|
||||
raw,
|
||||
CultureInfo.InvariantCulture,
|
||||
DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeUniversal,
|
||||
out var parsed))
|
||||
{
|
||||
throw new InvalidDataException(
|
||||
$"MTConnect streams response is malformed: observation '{dataItemId}' has an unparseable 'timestamp' ('{raw}').");
|
||||
}
|
||||
|
||||
// AdjustToUniversal already yields Utc; stated explicitly so a future styles change cannot
|
||||
// quietly hand the OPC UA layer a Local or Unspecified SourceTimestamp.
|
||||
return DateTime.SpecifyKind(parsed, DateTimeKind.Utc);
|
||||
}
|
||||
|
||||
private static bool IsObservationContainer(XElement element) =>
|
||||
ObservationContainers.Any(name => IsNamed(element, name));
|
||||
|
||||
private static bool IsNamed(XElement element, string localName) =>
|
||||
string.Equals(element.Name.LocalName, localName, StringComparison.Ordinal);
|
||||
|
||||
private static IEnumerable<XElement> ChildrenNamed(XElement parent, string localName) =>
|
||||
parent.Elements().Where(child => IsNamed(child, localName));
|
||||
|
||||
private static string RequiredAttribute(XElement element, string name, string owner)
|
||||
{
|
||||
var value = OptionalAttribute(element, name);
|
||||
|
||||
return value ?? throw new InvalidDataException(
|
||||
$"MTConnect streams response is malformed: {owner} has no '{name}' attribute.");
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Reads an unqualified attribute, normalizing a present-but-empty value to <c>null</c>.
|
||||
/// Only unqualified attributes are considered, so a namespace-prefixed vendor attribute can
|
||||
/// never be mistaken for an observation's identity or timestamp.
|
||||
/// </summary>
|
||||
private static string? OptionalAttribute(XElement element, string name)
|
||||
{
|
||||
var value = element.Attribute(name)?.Value;
|
||||
|
||||
return string.IsNullOrWhiteSpace(value) ? null : value;
|
||||
}
|
||||
|
||||
private static long RequiredLongAttribute(XElement header, string name)
|
||||
{
|
||||
var raw = RequiredAttribute(header, name, "The <Header>");
|
||||
|
||||
if (!long.TryParse(raw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var value))
|
||||
{
|
||||
throw new InvalidDataException(
|
||||
$"MTConnect streams response is malformed: the <Header> has a non-numeric '{name}' attribute ('{raw}').");
|
||||
}
|
||||
|
||||
return value;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Builds the message for a root element that is not <c>MTConnectStreams</c>, lifting the
|
||||
/// Agent's own error text when the response is an <c>MTConnectError</c> document (which
|
||||
/// Agents return under HTTP 200 for, e.g., a <c>from</c> outside the buffer).
|
||||
/// </summary>
|
||||
private static string DescribeUnexpectedRoot(XElement root)
|
||||
{
|
||||
var message =
|
||||
$"MTConnect streams response root element is <{root.Name.LocalName}>, expected <MTConnectStreams>.";
|
||||
|
||||
if (!IsNamed(root, "MTConnectError"))
|
||||
{
|
||||
return message;
|
||||
}
|
||||
|
||||
var errors = root.Descendants()
|
||||
.Where(e => IsNamed(e, "Error"))
|
||||
.Select(e =>
|
||||
{
|
||||
var code = OptionalAttribute(e, "errorCode");
|
||||
var text = e.Value.Trim();
|
||||
|
||||
return code is null ? text : $"{code}: {text}";
|
||||
})
|
||||
.Where(text => text.Length > 0)
|
||||
.ToList();
|
||||
|
||||
return errors.Count == 0
|
||||
? message
|
||||
: $"{message} The Agent reported: {string.Join("; ", errors)}";
|
||||
}
|
||||
}
|
||||
+6
-7
@@ -17,13 +17,12 @@
|
||||
<ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Contracts\ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Contracts.csproj"/>
|
||||
</ItemGroup>
|
||||
|
||||
<ItemGroup>
|
||||
<!-- Task 0 decision (verified 2026-07-24 against real nuget.org): TrakHound MTConnect.NET,
|
||||
MIT, netstandard2.0 lib (resolves on net10 via the in-box compat mapping). Pulls
|
||||
MTConnect.NET-TLS 6.9.0.2 transitively via -HTTP — expected, not a rogue dependency. -->
|
||||
<PackageReference Include="MTConnect.NET-Common"/>
|
||||
<PackageReference Include="MTConnect.NET-HTTP"/>
|
||||
</ItemGroup>
|
||||
<!-- No backend NuGet: the Agent surface is plain HTTP + XML, served entirely by the BCL
|
||||
(HttpClient + System.Xml.Linq). The TrakHound MTConnect.NET-Common/-HTTP references Task 0
|
||||
added were removed in Task 7 — they can neither parse an MTConnect document (no XML
|
||||
formatter ships in either package) nor frame the /sample stream socket-free (their client
|
||||
type dials its own URL). See the Task 0 CORRECTION block in
|
||||
docs/plans/2026-07-24-mtconnect-driver.md. -->
|
||||
|
||||
<ItemGroup>
|
||||
<InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests"/>
|
||||
|
||||
Reference in New Issue
Block a user