Developer Guide

For contributors working on the ZeroDDS codebase. Eight-section condensed handbook.

Codebase Tour

Single Cargo workspace, ~95 crates organised in nine layers:

Layer	Topic	Crate count
0	Foundation (errors, time, monitor, observability, flatdata)	8
1	Transport (UDP, TCP, SHM, TSN)	5
2	Wire Protocol (RTPS, discovery, builtin-topics)	6
3	Core Services (DCPS, QoS, security, types, sql-filter)	12
4	Schema (CDR, IDL, per-language code generators)	8
5	Protocol Bridges (WS / MQTT / CoAP / AMQP / gRPC / CORBA + bridge-security)	10
6	Language Bindings (C / C++ / C# / Java / Python / TS / Flutter)	11
7	Bridging Services (ROS-2 RMW, DLRL, OPC-UA, XRCE, web, soap)	11
8	CORBA + CCM (full OMG CORBA 3.3 + DDS4CCM 1.1 stack)	17

Cargo + MSRV

Workspace pins to Rust 1.88.0, Edition 2024 via rust-toolchain.toml. Layer-N crates may depend only on layers 0 .. N-1; cycles are detected by cargo run -p dds-lint -- check. No [workspace.dependencies] table — each crate manages its own dependency versions.

RC1 Definition-of-Done

Every crate must satisfy 13 checks before its tracker entry flips to ✅ rc1-ready. See RC1_GUARDRAILS.md:

Cargo.toml metadata complete
lib.rs / main.rs header with safety class + spec ref
README.md
CHANGELOG.md
Public-API audit
Coherence audit (CONNECTED / TEST-ONLY / DEAD)
Spec-coverage doc updated
Forbidden-token sweep
SPDX license headers per file
Tests + lints + doc build green
Review doc under docs/release/rc1-reviews/
Tracker entry ✅ rc1-ready
Public mirror under github/ + website/

Wire-Format Conventions

Two contracts:

RTPS 2.5 — crates/rtps/. Wire bytes verified against Cyclone DDS captures. Cross-vendor fixtures under crates/discovery/tests/fixtures/cyclone-xcdr2/.
XCDR1 / XCDR2 — crates/cdr/. Encoder + decoder for all primitive types, sequences, optionals, maps, unions, mutable structs (DHEADER + EMHEADER + PID), bitmasks. See the CDR Wire-Format Handbook.

Test Categories

Unit — in #[cfg(test)] mod tests alongside source.
Integration — in tests/ per crate.
Cross-vendor — gated behind #[ignore], run against external broker / DDS implementations in CI lab.
Fuzz — cargo fuzz harnesses in fuzz/ per protocol crate.
End-to-end — tests/interop/ with docker-compose for mosquitto / RabbitMQ / libcoap / omniORB / grpcurl / ros2-cyclone.

Spec-Coverage Workflow

Each OMG spec has a coverage doc under docs/spec-coverage/<spec>.md. Per section: Status ∈ {done, partial, open, n/a (informative), n/a (rejected)}, Repo link to source, Tests link to test functions. partial + open are RC1 blockers; n/a (rejected) needs an ADR under docs/adr/.

Public-Mirror Sync

Three trees in one repository:

./ — internal development tree, may contain llvm@llvm, internal hostnames, sprint markers.
github/ — public mirror after forbidden-token sweep. This is what gets pushed to github.com/zero-objects/zero-dds.
website/ — Public landing pages, manuals, claims, commercial. Deployed to zerodds.org.

The forbidden-token sweep runs in CI. Anything in github/ or website/ matching the forbidden list (internal hostnames, WP X.Y.Z sprint markers, etc.) blocks the merge.

Release Process

Audit all 90+ crates via cargo run -p tools/cargo-dag for publish-order.
Green CI on main: clippy, fmt, test, dds-lint, cargo-deny.
Tag 1.0.0-rc.1 on the workspace + per-crate tags.
Push github/ tree to github.com/zero-objects/zero-dds.
Publish to crates.io in DAG order.
Build packaging artifacts (.deb, .rpm, AppImage, Homebrew, MSI, Docker).
Deploy website/ to zerodds.org.

Full handbook on GitHub →