Joseph Doherty
c5d611d6fa
**F12 partial improvement** (`mxaccess-rpc::IUnknownHolder` + `mxaccess-nmx`):
- New `IUnknownHolder` newtype that owns an MTA-resident COM proxy
with `unsafe impl Send + Sync`. Mirrors the .NET reference's
`ManagedNmxService2Client._activatedComObject` private field
(`cs:15`).
- New `activate_and_marshal_iunknown_objref(prog_id, ctx)` returns
`(Vec<u8>, IUnknownHolder)`. Existing
`marshal_activated_iunknown_objref` retained as a wrapper that
drops the holder (kept for inline-use callers).
- `NmxClient` gains an `activated_com_object: Option<IUnknownHolder>`
field, populated by `Self::create` from the new helper.
`Self::connect` / `Self::from_bound_transport` set it `None` (no
COM activation in those paths).
- Holding the IUnknown for the client's lifetime keeps the
SCM-tracked OXID valid; without it the COM ref count drops to
zero and the SCM may release the activated server-side instance,
making subsequent `ResolveOxid` / `RemQueryInterface` calls
return `RPC_S_SERVER_UNAVAILABLE`.
**F55 (new) — hand-rolled callback exporter rejected by RegisterEngine2**
Five-step instrumentation of `Session::connect_nmx_auto` proves all
six COM-activation / RemQI / final-bind steps succeed. The 1722
fault originates at `RegisterEngine2` itself:
```
from_nmx_client: callback hostname="DESKTOP-6JL3KKO" port=57886 obj_ref_len=162
from_nmx_client: callback obj_ref hex: 4d454f57010000...
from_nmx_client: RegisterEngine2 (31112, mxaccess.31112)
from_nmx_client: RegisterEngine2 FAIL: Transport(Fault { status: 2147944122 })
```
Status `0x800706BA` = `RPC_S_SERVER_UNAVAILABLE` wrapped as Win32
HRESULT.
**Critical finding: the .NET reference's `--probe-register-managed-callback`
(which uses the same hand-rolled `ManagedCallbackExporter` approach
as the Rust port) ALSO fails with the same `0x800706BA` fault.**
Only `--probe-session-write`, which uses
`ComObjRefProvider.MarshalInterfaceObjRef(callback, ...)` to build
the OBJREF via Windows DCOM proxy/stub marshalling, succeeds. So
this is an architectural artifact of the hand-rolled-callback
design, not a Rust port regression.
`design/followups.md` F55 entry documents the three resolution
paths (switch to DCOM-marshalled callback / hybrid / continue
investigating OBJREF rejection at NmxSvc).
F49 stays open with a refined diagnostic — the per-feature live
verification is gated on F55's resolution.
Workspace tests still 824 passing; clippy `-D warnings` clean
across both feature configurations.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
design/ — Rust port architectural plan
This folder is the design contract for the Rust replacement of AVEVA/Wonderware MXAccess. It is the gap between the .NET reference in src/ and the Rust crates that will be written under a sibling rust/ workspace (per CLAUDE.md).
The folder is structured as a small set of focused documents. Read in order; each builds on the previous.
| File | Purpose |
|---|---|
00-overview.md |
Mission, two-layer goal, architectural principles, non-goals |
10-raw-layer.md |
Byte-accurate raw MXAccess layer (codec + transport + session) |
20-async-layer.md |
Idiomatic Tokio async layer on top of the raw layer |
30-crate-topology.md |
Cargo workspace, crates, dependencies, build/test commands |
40-protocol-invariants.md |
Bill of materials: IIDs, opnums, envelope/handle bytes |
50-error-model.md |
MxStatus, error types, panic/cancellation policy |
60-roadmap.md |
Milestones M0..M6, validation strategy |
70-risks-and-open-questions.md |
Parity gaps, unproven flows, cross-platform constraints |
dependencies.md |
Cross- and within-milestone parallelism map; agent budget per phase |
review.md |
Adversarial review log (BLOCKER/MAJOR/MINOR/NIT findings, all resolved) |
prompt.md |
/loop driver prompt for autonomous M2–M6 execution |
followups.md |
Open / resolved deferred work items; auto-triaged by prompt.md Step 0 (created on first /loop run if missing) |
The design is grounded in the .NET reference at src/ and the protocol artifacts in docs/, analysis/, and captures/. Do not introduce protocol behavior in these documents that is not already proven in the reference. When adding a new claim about wire format, cite either:
- a
.csfile path insrc/MxNativeCodec/,src/MxNativeClient/, orsrc/MxAsbClient/, or - a
docs/*.mdspec file, or - a
captures/0NN-frida-*directory oranalysis/frida/*.tsvrow.
This folder is documentation, not code. When the Rust workspace is created, the design here is the contract it must satisfy. When evidence in captures/ invalidates a design decision here, update the design first, then the code.
Reading order
- New contributor: 00 → 30 → 10 → 40 → 20 → 50 → 60 → 70.
- Protocol question: 40 first, then the relevant section of 10.
- API question: 20 first, then 50.
- Planning a milestone: 60 first, cross-reference 70 for blockers.
- Scheduling concurrent work:
dependencies.mdfor the per-phase parallelism map. - Driving M2–M6 autonomously via
/loop:prompt.md(and thefollowups.mdtriage log it maintains).