ROS 2 Distribution Compatibility

ros-z supports multiple ROS 2 distributions through compile-time feature flags. This chapter explains the differences between distributions and how to target specific ROS 2 versions.

Important: Different ros-z components have different ROS 2 version requirements:

• ros-z core library: Supports Humble, Jazzy, Kilted, Rolling
• rmw-zenoh-rs: Requires Jazzy or later (see rmw-zenoh-rs chapter)

Supported Distributions

Default: ros-z defaults to Jazzy compatibility, which is the recommended distribution for new projects.

Distribution Differences

Type Hash Support

The most significant difference between distributions is type hash support:

Jazzy/Kilted/Rolling (Modern):

• Supports real type hashes computed from message definitions
• Format: RIHS01_<64-hex-chars> (ROS IDL Hash Standard version 1)
• Enables type safety checks during pub/sub matching
• Type hashes are embedded in Zenoh key expressions for discovery

Humble (Legacy):

• Does not support real type hashes
• Uses constant placeholder: "TypeHashNotSupported"
• No type safety validation during discovery
• Compatible with rmw_zenoh_cpp v0.1.8

Example Key Expressions

Jazzy:

@ros2_lv/0/<zid>/<nid>/<eid>/MP/%/<namespace>/<node>/chatter/std_msgs%msg%String/RIHS01_1234567890abcdef.../...

Humble:

@ros2_lv/0/<zid>/<nid>/<eid>/MP/%/<namespace>/<node>/chatter/std_msgs%msg%String/TypeHashNotSupported/...

Building for Different Distributions

Using Jazzy (Default)

By default, ros-z builds with Jazzy compatibility. No special flags needed:

# Build with default (Jazzy)
cargo build

# Run examples
cargo run --example demo_nodes_talker

# Run tests
cargo nextest run

Using Humble

To build for Humble, use --no-default-features --features humble:

# Build for Humble
cargo build --no-default-features --features humble

# Run examples for Humble
cargo run --no-default-features --features humble --example demo_nodes_talker

# Run tests for Humble
cargo nextest run --no-default-features --features humble

Using Other Distributions

For Rolling or Kilted, simply specify the distro feature:

# Build for Rolling
cargo build --features rolling

# Build for Kilted
cargo build --features kilted