# ros2_message

[![MIT Licensed](https://img.shields.io/crates/l/ros2_message.svg?maxAge=3600)](./LICENSE)
[![Crates.io](https://img.shields.io/crates/v/ros2_message.svg?maxAge=3600)](https://crates.io/crates/ros2_message)

> [!WARNING]
> This crate is not extensively tested yet and there is a good chance that you will discover issues.
> If you do please [create a GitHub Issue](https://github.com/A-K-O-R-A/ros2_message/issues/new)

**ros2_message** is a utility library for handling anything related to [ROS2](https://ros.org/) `.msg` and `.srv` files in Rust.
It's primary focus is dynamically parsing and decoding ROS2 messages. The most common usecase for this is the [mcap](https://crates.io/crates/mcap) file format.
For more information take a look at the [`Msg`](https://docs.rs/ros2_message/latest/ros2_message/struct.Msg.html) and
[`DynamicMsg`](https://docs.rs/ros2_message/latest/ros2_message/dynamic/decode/struct.DynamicMsg.html) structs.

The most common use case for this is reading out MCAP files, especially in a environment where installing ROS2 is not an option.
For more information about that have a look at the the [mcap_reading](https://github.com/A-K-O-R-A/ros2_message/blob/master/examples/examples/mcap_reading.rs) example
in the [examples](https://github.com/A-K-O-R-A/ros2_message/blob/master/examples/examples/) folder.


## Implementation status
 - [ ] Implementing the full CDR spec
   - [x] Little endian plain CDR is supported
   - [ ] Big endian plain CDR
   - [ ] PL CDR & CDR2
 - [ ] Extensive testing for different encoded messages


## Resources
 - [ROS2 documentation](https://docs.ros.org/)
 - [Interface documentation](https://docs.ros.org/en/iron/Concepts/Basic/About-Interfaces.html#messages)
 - [CDR Spec](https://www.omg.org/spec/DDS-XTypes/1.3/PDF), CDR types are specified under 7.4.3.4

### Foxglove `.msg` file parsing implemenation
 - [foxglove/message-definition](https://github.com/foxglove/message-definition/)

### Foxglove dynamic decoding implementation
  - [ROS2 specific deserialization](https://github.com/foxglove/rosmsg2-serialization/blob/d262e58a47138c4725e0d7a4881eb45c7eea1cc2/src/MessageReader.ts)
  - [CDR implementation](https://github.com/foxglove/cdr/blob/5cdd02e0be6fe5e7f4424f91d59d451f56459d33/src/CdrReader.ts)
  - [Overview of all the CDR encapsulation kinds](https://github.com/foxglove/cdr/blob/5cdd02e0be6fe5e7f4424f91d59d451f56459d33/src/EncapsulationKind.ts)
  - [ROS2 Message implementation](https://github.com/foxglove/rosmsg/tree/main)