Roadmap Milestone 2 (event sending). Capture disproved the assumption that event
delivery uses the non-WCF storage-engine pipe (which would block it like revision
writes): a native AddStreamedValue(HistorianEvent) leaves over WCF as AddS2
(IHistoryServiceContract2.AddStreamValues2). CM_EVENT is a built-in registered tag,
so the 129 TagNotFoundInCache gate that blocks AddS2 for user tags does not apply.
- R2.1: NativeTraceHarness "event-send" scenario + Capture-EventSend.ps1; two
captures diffed to separate constant framing from value-dependent fields.
- R2.2: HistorianEventWriteProtocol serializes the AddS2 pBuf (storage sample buffer
wrapping the event VTQ) — golden-byte tested. Decoded "OS" sig + length fields +
CM_EVENT tag id + EventTime/ReceivedTime FILETIMEs + Opc 192 + 0x118D descriptor +
event Id + Namespace + EventType + version 5 + typed property bag.
- R2.3/R2.4: HistorianWcfEventOrchestrator.SendEventAsync (Open2 event-mode 0x501 ->
reuse CM_EVENT RTag2/EnsT2 -> AddStreamValues2) + HistorianClient.SendEventAsync.
- R2.5: gated live test; server accepts the AddS2 (success, empty error buffer).
Server requires delivered byte[].Length == declared packet length (uint32@0x04); the
native relies on the MDAS encoder adding a pad byte, so the SDK emits an explicit
trailing 0x00 (else AddS2 rejects with "CValuStream buffer size vs packet length
mismatch"). Original events only (RevisionVersion=0) with string properties; other
property types + revision/update/delete throw ProtocolEvidenceMissingException.
Caveat (documented): accepted events are not persisted on the local dev box; the
native client behaves identically (event ingestion pipeline inactive) — not an SDK
gap. 212 unit tests pass; 16/16 event tests pass live.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC
Version-control the planning docs alongside the code they describe:
- grpc-transport.md — 2023 R2 gRPC transport analysis (sanitized source path)
- hcal-capability-matrix.md — HistorianAccess surface x gRPC ops x histsdk status x feasibility tiers
- hcal-roadmap.md — ordered build plan M0-M4 + cross-cutting workstreams
- histevents.md — how a HistorianEvent reaches the DB (client->wire->server)
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Joseph Doherty