Versioning¶

An API's version is its crate's version, and the same goes for every trait and type: a #[ww_trait] or a data type from another crate is identified by that crate's name and version. ww_version::FullVersion carries both; codegen puts the API root's into a <ROOT_TRAIT>_FULL_GID constant (BLINKY_API_FULL_GID), which the device reports when a host connects.

On connection, a generated client checks the device's API crate name and version against its own and refuses an incompatible device with Error::IncompatibleDeviceProtocol. Compatible means SemVer-compatible: the same major version from 1.0 on, the same major and minor before it (Version::is_protocol_compatible). Within that range the evolution rules keep old and new talking: added methods, appended fields, new enum variants. The dynamic client, the ww CLI and Python take the device's API from its introspection data, so they don't check.

Reusable traits are found by their crate's name and version too, whatever the device's own API is, see global trait addressing. The types are on the ww_version page.