blew 0.2.0-alpha.2

Cross-platform async BLE library for Rust (Apple, Linux, Android)
Documentation

Crates.io Docs.rs

blew

🔥 Warning 🔥 This library is in alpha state and is subject to change without backwards-compatibility until otherwise noted.

blew is a BLE (Bluetooth Low Energy) Rust library focused on enabling peer-to-peer applications, and was built as the backend for iroh-ble-transport.

It differs from other libraries in that it implements both Central and Peripheral modes, and aims to provide support for macOS, iOS, Android, and Linux. It is also async-only and requires a Tokio runtime.

It also supports opportunistic L2CAP which provides a lower-level socket-type interface that tends to be significantly faster than using GATT for data transfer.

blew is intended to support as many concurrent L2CAP channels as the device and platform can sustain. Backend implementations should therefore optimize for high L2CAP concurrency, not just single-channel correctness.

For Tauri users, see the companion crate tauri-plugin-blew that vastly simplifies the necessary setup of the Kotlin/JNI glue to enable Android functionality.

Supported Platforms

Platform Backend Central Peripheral L2CAP
macOS / iOS CoreBluetooth (via objc2) Yes Yes Yes
Linux BlueZ (via bluer) Yes Yes Yes
Android JNI + Kotlin (via jni and ndk-context) Yes Yes Yes

Examples

cargo run --example scan -p blew          # scan for 10s, print discoveries
cargo run --example advertise -p blew     # advertise a GATT service, handle reads/writes
cargo run --example l2cap_server -p blew  # peripheral: publish L2CAP CoC, echo data
cargo run --example l2cap_client -p blew  # central: scan, connect, open L2CAP, send data
cargo run --example restore -p blew       # iOS state-restoration launch sequence

The integration_peripheral / integration_central pair is a scripted real-hardware smoke test -- run them on two separate hosts to verify the backend end-to-end. See the top-level README for details.

Alternative Libraries

This library was customized primarily to be used for Iroh, and there are plenty of great alternatives out there! I'm sure I'm missing some, but to name a few that are actively maintained:

License

This project is licensed under the GNU Affero General Public License v3.0 or later.

Commercial licenses are available for use cases where the AGPL is not suitable. Contact me@jakebot.org for details.