# Google Cloud Client Libraries for Rust - Pub/Sub
**WARNING:** this crate is under active development. We expect multiple breaking
changes in the upcoming releases. Testing is also incomplete, we do **not**
recommend that you use this crate in production. We welcome feedback about the
APIs, documentation, missing features, bugs, etc.
This crate contains traits, types, and functions to interact with [Pub/Sub].
Most applications will use the structs defined in the client module.
Receiving messages is not yet supported by this crate.
> This crate used to contain a different implementation, with a different
> surface. [@yoshidan](https://github.com/yoshidan) generously donated the crate
> name to Google. Their crate continues to live as [gcloud-pubsub].
## Features
- `default-rustls-provider`: enabled by default. Use the default rustls crypto
provider ([aws-lc-rs]) for TLS and authentication. Applications with specific
requirements for cryptography (such as exclusively using the [ring] crate)
should disable this default and call
`rustls::crypto::CryptoProvider::install_default()`.
- `unstable-stream`: enable the (unstable) features to convert several types to
a `future::Stream`.
[aws-lc-rs]: https://crates.io/crates/aws-lc-rs
[gcloud-pubsub]: https://crates.io/crates/gcloud-pubsub
[pub/sub]: https://cloud.google.com/pubsub
[ring]: https://crates.io/crates/ring