Files
mxaccess/design
Joseph Doherty e3baeb8803 [M5] mxaccess: F26 step 3 — AsbSession high-level cheap-clone async API
Adds the public high-level entry point for the ASB transport.
Parallel to the NMX-shaped `Session` (rather than unified) because
NMX's `Session` carries CallbackExporter / callback router task /
recovery broadcast / INmxService2 mutex orchestration that has no
ASB analogue — and ASB's request/response loop over a single TCP
stream maps naturally to `Mutex<AsbClient>` that would be foreign
to NMX. Two paths converge at the consumer-facing API but stay
distinct at the orchestration layer.

Struct shape:
```rust
pub struct AsbSession { inner: Arc<AsbSessionInner> }
struct AsbSessionInner {
    transport: Mutex<AsbTransport<TcpStream>>,
    connect_response: ConnectResponse,
}
```

`Clone + Send + Sync` — clones share state through `Arc`, lock
serialises operations. Compile-time `assert_clone_send_sync` test
guards the contract.

API:
* `connect(endpoint, passphrase, crypto_parameters, via_uri,
  connection_id)` — full bring-up (TCP + preamble + DH handshake).
* `from_transport(transport, connect_response)` — build from an
  existing transport (tests, custom transports).
* `connect_response()` — surface the negotiated lifetime /
  Apollo flag.

Operation methods forward to AsbClient:
* `register_items` / `unregister_items` / `read` / `write`
* `keep_alive` / `disconnect`
* `create_subscription` / `add_monitored_items` / `publish` /
  `delete_monitored_items` / `delete_subscription`
* `publish_write_complete`

ClientError → mxaccess::Error mapping via
`ConnectionError::TransportFailure` (consistent with F26 step 2).

1 new test:
* `asb_session_is_clone_send_sync` — compile-time trait-bound
  assertion.

Workspace: 702 tests pass.

Stubbed for next F26 iteration:
* `Stream<Item = MonitoredItemValue>` subscription handle that
  internally drives a publish-loop. Today consumers loop
  `publish().await` themselves.
* Recovery / reconnect policy — needs a captured ASB-side
  disconnect to inform the retry strategy.
* Live-probe wire-byte reconciliation against the WCF DataContract
  XML serializer's actual output.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 13:23:59 -04:00
..

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 M2M6 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 .cs file path in src/MxNativeCodec/, src/MxNativeClient/, or src/MxAsbClient/, or
  • a docs/*.md spec file, or
  • a captures/0NN-frida-* directory or analysis/frida/*.tsv row.

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.md for the per-phase parallelism map.
  • Driving M2M6 autonomously via /loop: prompt.md (and the followups.md triage log it maintains).