Files
mxaccess/design
Joseph Doherty c4bf0a0a04 [M5] mxaccess-asb: F25 step 3 — response decoders + Read request body
Foundation for response decoding. Adds:

* `contracts::ItemStatus` — ports `AsbContracts.cs:639-722`. Wire
  layout matches `WriteToStream` exactly: Item (ItemIdentity binary)
  → Status (AsbStatus binary, from F24) → ErrorCode (u16) →
  ErrorCodeSpecified (u8 bool). Note this is NOT the DataMember
  declaration order — the binary serialiser hand-picks Item-first.

* `encode_item_status_array` / `decode_item_status_array` — same
  4-byte int32 count + per-element WriteToStream pattern as the
  ItemIdentity array codec.

* `operations::collect_asbidata_payloads(tokens, field_name)` — walks
  an NBFX token stream and pulls out `<{field}><ASBIData>{Bytes}
  </ASBIData></{field}>` payload bytes. Returns Vec<Vec<u8>> because
  some response shapes (ReadResponse) carry multiple ASBIData
  payloads (Status + Values).

* `decode_register_items_response` / `decode_unregister_items_response`
  — parse SOAP body NBFX tokens into typed RegisterItemsResponse /
  UnregisterItemsResponse. The optional ItemCapabilities array (XML-
  serialised, not binary) is recorded as a presence flag for now;
  decoding the individual ItemRegistration records is a follow-up.

* `build_read_request_body(items)` — simplest unary IASBIDataV2
  request, just `<ReadRequest xmlns="..."><Items><ASBIData>...
  </ASBIData></Items></ReadRequest>`.

* `OperationError` — typed error for response-decode failures
  (`MissingField { field }` and codec wraps).

9 new tests: ItemStatus round-trip (default + with id + with status
payload), ItemStatus array round-trip, RegisterItemsResponse
round-trip via synthetic body, ItemCapabilities presence detection,
UnregisterItemsResponse round-trip, multi-payload extraction (ReadResponse-
shape Status + Values), Read body shape correctness, MissingField
error when Status is absent.

Stubbed for next F25 iteration: Write / PublishWriteComplete /
CreateSubscription / AddMonitoredItems / DeleteMonitoredItems /
Publish builders, ReadResponse + WriteResponse decoders (need
WriteValue / RuntimeValue contract codecs), and the AsbClient
network loop.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 11:32:36 -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).