Pursued hypothesis #3 (connection-frame capture). Built a TLS-terminating tee proxy
(artifacts/.../httpcap/, gitignored: self-signed server cert, forwards through the
loopback tunnel, logs decrypted HTTP/1.1 + gRPC-Web both directions) and ran a native
capture-event (returns 50 rows) and our SDK diagnostic (0 rows) through the SAME
proxy/upstream for a clean A/B.
Findings:
- The stock client is gRPC-Web/HTTP-1.1 (alpn empty), and clientCert=none on every
connection — confirming (with the decompile) that hypothesis #2 (TLS client cert) is
moot: the native presents no client cert.
- Connection topology differs: the native opens 5 TLS connections, one per service, and
runs the event query (StartEventQuery/GetNext/EndEventQuery) on a DEDICATED
RetrievalService connection, separate from the HistoryService connection that opened and
registered the session. Our SDK collapses every service onto one connection. (Matches the
decompile: the stock client has a separate GrpcClientBase per service.)
- Framing differs benignly: native uses content-length + Expect: 100-continue; SDK uses
transfer-encoding: chunked. The server accepts both (StartEventQuery returns a valid
handle), so framing is not the gate. No hidden header on either side.
Tested the topology hypothesis with a new env-gated switch
(HISTORIAN_GRPC_EVENT_SPLIT_CHANNEL=1): run StartEventQuery/GetNext/EndEventQuery on a
dedicated RetrievalService connection (no re-handshake, reusing the session handle —
mirroring native conn4), registration staying on the main connection. Result: still
0B00000000001E000000 (0 rows), QH=1063. Splitting the event query onto its own connection
does not make rows flow — the server correlates by session handle, not connection, so
topology is not the row-scoping gate.
Every angle is now exhausted (payload, transport, metadata/interceptor/cert, topology,
data store). The gate is a server-internal per-connection retrieval working-set in the
native HistorianClient C++ core, unreachable from a pure-managed client. Conclusion
unchanged: auth-solved / retrieval-server-gated; ReadEventsAsync over gRPC keeps the
no-row throw, event reads use WCF. 56 offline gRPC/event tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC
Joseph Doherty
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