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write-commands plan: AddS2 prereq is architectural - not implementable as generic client write

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Three follow-up attempts to satisfy the AddS2 server-cache prereq all
failed at the same client-side gate before any AddS2 byte reached the
wire:

1. TagKey synthetic→real override. First attempt used the placeholder
   TagKey=10000000 returned by HistorianAccess.AddTag. Native
   AddStreamedValue refused with error 168 "Tag not added to server".
   Harness now ALWAYS resolves the real wwTagKey from Runtime.dbo.Tag
   after AddTag (logged as TagKeyOverride: Synthetic→RealFromSql).
   Error code shifted to 129 "Tag not found in cache" — request now
   reaches the server but the server's in-memory tag cache doesn't
   know about the new tag.

2. Server-cache settle wait. Up to 8s sleep between AddTag and
   AddStreamedValue (--write-resync-wait-seconds N). Wait period
   contains 2× UpdC3 + 2× Trx/GetV keep-alives but no server-side
   cache update — error 129 persists.

3. Fresh process / fresh connection. Skipped AddTag entirely
   (--write-skip-add-tag) and ran AddStreamedValue alone against the
   already-existing sandbox tag. New native client instance, new
   client-side cache, new server session. SAME error 129 — no AddS2
   bytes sent on wire. Capture confirms 44 records ending in Close2.

Interpretation: the Historian engine's runtime tag cache only ingests
tags from configured IOServers / Application Server data pipelines,
not from HistorianAccess.AddTag-only client flows. AddTag populates
Runtime.dbo.Tag (wwTagKey=240 was created) but doesn't register the
tag with the live cache that AddStreamedValue checks. That
registration happens server-side when an upstream data producer (an
OPC driver, AnE event subsystem, Application Server attribute store)
claims the tag.

WriteValueAsync therefore CANNOT be implemented as a generic client
API against this server architecture. The SDK's realistic writeable
surface is now narrowed to EnsureTagAsync + DeleteTagAsync only.

Harness changes:
- --write-skip-add-tag    skip the AddTag call (for fresh-cache test)
- --write-skip-add-value  skip the AddStreamedValue call (capture EnsT2 only)
- --write-resync-wait-seconds N  sleep N seconds between AddTag and
                                  AddStreamedValue (default 0)
- TagKey lookup now ALWAYS hits SQL after AddTag, not just when
  the synthetic key is 0.

Plan doc updated with full Phase 2 follow-on findings + revised
remaining work (4-item checklist focused on EnsureTagAsync/
DeleteTagAsync, plus a stretch goal of probing AddRevisionValues*
against an existing-tag).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
dohertj2
2026-05-04 08:06:28 -04:00
parent b5f9a71fe7
commit b3d22befd0
2 changed files with 119 additions and 33 deletions
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tools/AVEVA.Historian.NativeTraceHarness/Program.cs
+46 -21
View File
@@ -228,6 +228,11 @@ internal static class Program
}
string writeDataTypeName = GetArg(args, "--write-data-type") ?? "Float";
double writeValue = double.TryParse(GetArg(args, "--write-value"), out double parsedValue) ? parsedValue : 42.5;
// --write-skip-add-tag lets the value-only second pass run without re-creating
// the sandbox. The connection's tag cache is bound at OpenConnection time, so the
// server-cache refresh after a fresh AddTag requires a NEW process / connection.
bool skipAddTag = HasFlag(args, "--write-skip-add-tag");
bool skipAddValue = HasFlag(args, "--write-skip-add-value");
// Decoded via dnlib — actual enum field types on HistorianTag:
// set_TagDataType stfld ArchestrA.HistorianDataType HistorianTag::dataType
@@ -254,28 +259,34 @@ internal static class Program
SetProperty(tag, "ApplyScaling", false);
uint tagKey = 0;
object addError = Activator.CreateInstance(errorType)!;
MethodInfo addTagMethod = accessType.GetMethod("AddTag", new[] { tagDefType, typeof(uint).MakeByRefType(), errorType.MakeByRefType() })
?? throw new MissingMethodException("HistorianAccess.AddTag");
WriteRuntimeMethodPointerSnapshot(assembly, runtimeMethodPointerOutput, runtimeMethodPointerFilters, repoRoot, scenario, "before-add-tag");
object?[] addTagArgs = [tag, tagKey, addError];
bool addTagSuccess = (bool)addTagMethod.Invoke(access, addTagArgs)!;
tagKey = (uint)addTagArgs[1]!;
addError = addTagArgs[2]!;
snapshots["TagAfterAddTag"] = SnapshotObject(tag);
snapshots["AddTagError"] = SnapshotObject(addError);
rows.Add(new
if (!skipAddTag)
{
Kind = "AddTag",
Success = addTagSuccess,
TagKey = tagKey,
ErrorDescription = GetPropertyText(addError, "ErrorDescription"),
});
object addError = Activator.CreateInstance(errorType)!;
MethodInfo addTagMethod = accessType.GetMethod("AddTag", new[] { tagDefType, typeof(uint).MakeByRefType(), errorType.MakeByRefType() })
?? throw new MissingMethodException("HistorianAccess.AddTag");
WriteRuntimeMethodPointerSnapshot(assembly, runtimeMethodPointerOutput, runtimeMethodPointerFilters, repoRoot, scenario, "before-add-tag");
object?[] addTagArgs = [tag, tagKey, addError];
bool addTagSuccess = (bool)addTagMethod.Invoke(access, addTagArgs)!;
tagKey = (uint)addTagArgs[1]!;
addError = addTagArgs[2]!;
snapshots["TagAfterAddTag"] = SnapshotObject(tag);
snapshots["AddTagError"] = SnapshotObject(addError);
rows.Add(new
{
Kind = "AddTag",
Success = addTagSuccess,
TagKey = tagKey,
ErrorDescription = GetPropertyText(addError, "ErrorDescription"),
});
}
// If AddTag returned no key (tag already exists from a prior session), look it up.
if (tagKey == 0)
// ALWAYS look up the real wwTagKey from SQL — AddTag returns a synthetic
// placeholder key (~10000000) when the tag is freshly created, but the server
// session cache only recognizes the real Runtime.dbo.Tag.wwTagKey value
// (small int). Using the synthetic key in AddStreamedValue causes server-side
// error 168 "Tag not added to server".
using (System.Data.SqlClient.SqlConnection sql = new("Server=.;Database=Runtime;Integrated Security=SSPI;"))
{
using System.Data.SqlClient.SqlConnection sql = new("Server=.;Database=Runtime;Integrated Security=SSPI;");
sql.Open();
using System.Data.SqlClient.SqlCommand cmd = sql.CreateCommand();
cmd.CommandText = "SELECT wwTagKey FROM Tag WHERE TagName = @t";
@@ -283,12 +294,26 @@ internal static class Program
object? result = cmd.ExecuteScalar();
if (result is int existingKey)
{
tagKey = (uint)existingKey;
uint realKey = (uint)existingKey;
if (realKey != tagKey)
{
rows.Add(new { Kind = "TagKeyOverride", Synthetic = tagKey, RealFromSql = realKey });
tagKey = realKey;
}
}
}
// Server cache may not pick up new tags immediately. Allow a wait between AddTag
// and AddStreamedValue so the server side has time to add the new tag to its
// in-memory cache. Configurable via --write-resync-wait-seconds (default 8).
int resyncWait = int.TryParse(GetArg(args, "--write-resync-wait-seconds"), out int w) ? w : 8;
if (resyncWait > 0)
{
Thread.Sleep(TimeSpan.FromSeconds(resyncWait));
}
// Build HistorianDataValue + push it (drives AddS2 on the wire).
if (tagKey != 0)
if (tagKey != 0 && !skipAddValue)
{
object value = Activator.CreateInstance(dataValueType)!;
SetProperty(value, "TagKey", tagKey);