Files
mxaccess/design
Joseph Doherty 9dfd1937c2 [M5] mxaccess-asb-nettcp: F20 [MS-NMF] .NET Message Framing record codec
Implements the 13 record types from `[MS-NMF]` §2.2 (Version, Mode, Via,
KnownEncoding, ExtensibleEncoding, Unsized/SizedEnvelope, End, Fault,
UpgradeRequest/Response, PreambleAck, PreambleEnd) over a `net.tcp` channel.

Includes the `Multibyte Int31` length codec (LEB128-style 7-bit groups
over a 31-bit unsigned range, max 5 bytes; rejects negative input and
overflow), plus an `encode_preamble` helper that emits the canonical ASB
connect record sequence (`Version 1.0 → Duplex → Via $uri →
BinaryWithDictionary → PreambleEnd`).

Pure codec — no I/O. Encoders write into a `Vec<u8>`; decoders parse
from a `&[u8]` slice and return the consumed-byte count alongside the
record. Higher-level connect/request/response orchestration stays in the
M5 ASB client (`mxaccess-asb`, F25).

24 new unit tests cover round-trip for every record type, multibyte-int31
boundary cases (0, 1, 127, 128, 16383, 16384, 200, i32::MAX), preamble
emission against the canonical ASB sequence, byte-layout pinning for
Version/Mode/KnownEncoding, and rejection of unknown record/mode/encoding
bytes plus truncated sized-envelope frames.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 11:01:24 -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).