Weld

License: GNU Affero General Public License v3.0 or later (/LICENSE)

Weld is middleware for distributed communication written in Go. One unified core moves
topics, services, actions, and parameters across transports, with
structured delivery, copy once handling, and a leaderless data plane
that stays correct under partition. Version one ships the DDS backend
against CycloneDDS, the only supported DDS.

Weld speaks ROS 2 on the wire, so Go programs join ROS 2 systems as
first-class nodes, verified by mixed fleet behavior.

Security

  Weld implements no transport crypto. DDS Security handshake, crypto
  transforms, access control, and revocation are explicitly out of
  scope and refused loudly instead of attempted, so a secured peer
  never degrades silently. Encryption and authentication in transit
  come from the deployment, not the middleware. On Concord-coordinated
  machines node-to-node links run inside the encrypted WireGuard mesh,
  and Concord sync sessions add mutually authenticated Noise IK channels
  with fleet membership checked before a single byte flows, so the fleet
  is secured by default by the platform Weld runs on. See docs/interop
  for the refused-with-reason list.

Scope

  Weld is consolidated, not expanding. CycloneDDS is the only
  transport and no others will be added. All work goes inward:
  correctness, reliability, verification, and optimization of what
  is already here. No new surface, fixes only.

  The bar, same for every change: externally identical behavior.
  Optimization needs a measurement before and after, not a hunch.
  Replacement needs the same wire format, CLI surface, and journal
  semantics, proven by the existing gate plus a Resonance run, not
  by reading the diff. Fixes need a failing gate first, then the
  smallest patch that turns it green without moving any other
  number. Cleanup needs the full gate green on both sides; elegance
  in the diff proves nothing. Anything adding a flag, a verb, or a
  field is expansion, and the answer is no until the freeze lifts.

Weld is faster than ROS 2 on the same host: up to 68% lower latency.

It also scales further: zero packet loss where ROS starts dropping,
with about 25% more throughput.

Benchmarks

  Weld versus ROS 2 (ros-jazzy/CycloneDDS), same host and bytes, full
  matrix green (110 rows, exit 0; reports in testbed/logs/bench-*.html).
  Weld-to-weld latency is lower than ros-to-ros at every payload size
  (16 to 68% lower p50 from 64 B to 1 MiB) and every lossless rate
  (about 50% lower through 100 to 800 Hz at 1 KiB). Weld legs hold 0%
  loss from 50 Hz to 100 kHz offered; ros-to-ros first drops at 10 kHz.
  Full tables, the latency-vs-throughput chart, and caveats live in
  testbed/bench/README.

  Chart (testbed/bench/latency-vs-throughput.svg): latency vs achieved
  throughput, 1 KiB sweep, one p50 curve per leg in leg colors with
  circle markers, p99 dashed with triangles; red rings mark lossy rates.

Documentation

  Start here:
    Overview - /docs/overview
    Weld design - /docs/design
    Weld invariants - /docs/invariants
    Glossary - /docs/glossary
    FAQ - /docs/faq
    Deployment - /docs/deployment

  Wire and types:
    Types - /docs/types
    Type hashes - /docs/hash
    CDR - /docs/cdr
    Introspection and bounds - /docs/introspection
    Corpus - /docs/corpus
    QoS - /docs/qos
    Transports - /docs/transports
    Interop - /docs/interop

  System:
    Actions - /docs/actions
    Services - /docs/services
    Config - /docs/config
    Supervision - /docs/supervision
    Time - /docs/time

  Fleet and tools:
    Testbed - /docs/testbed
    Testbed Go - /docs/testbed-go
    Conformance - /docs/conformance
    Wireless - /docs/wireless
    CLI - /docs/cli

Contributing

Discuss your change with the engineering team at contact@podomy.com
before opening a PR in order not to waste anybody's effort or time.

Announcements and engineering updates on distributed systems, consensus
algorithms, and robotic fleet coordination are shared via our newsletter
at https://podomy.com.

  Commit message format - /COMMITS
  Contributor license agreement - /CLA
  Contributing - /CONTRIBUTING

License

Weld is distributed under the GNU Affero General Public License v3.0 or
later. See /LICENSE.