GSoC 2024 Qaul: Qaul BLE module for Linux


The project aims to create a qaul Ble(Bluetooth low energy) module in Rust for Linux which is compatible with Ble modules for Android and iOS. The module should provide the following functionalities :

  1. BLE discovery and connections: The project should be able to scan other discoverable devices and send BLE advertisements to nearby nodes at regular intervals.
  2. Establish data communication: The connection should be able to exchange messages between qaul nodes.

Plan Of Action

This project aims to establish a BLE connection between Linux and other compatible devices.

BLE GATT Service ➖

  • GATT Server: A GATT server corresponds to an ATT server. It receives requests from clients and sends responses back.
  • GATT Client: A GATT client corresponds to an ATT client. It sends requests to the server and receives responses. After the discovery of the server’s service attributes, it can start reading/writing about attributes found on the server based on permissions provided by the server.

GATT data hierarchy.


  • Initiate BLE GATT server  :
    • Initialize the Bluetooth session and activate the Bluetooth adapter.
    • Initiate local Ble GATT server using the bluer crate and set up Bluetooth GATT Services and Characteristics, which become available for remote servers.
  • Initiate BLE GATT client :
    • Initiate advertisement to look for nearby qaul nodes with specified service UUID and characteristic UUID.
    • Connect to discovered devices and send RPC messages to libqaul.
  • Establish communication between devices :
    • On receiving the message.DirectSend request from the libqaul. Write the data into the characteristic.value if the service.UUID() and characteristic.UUID() is compatible with other qaul devices.
    • Create a message listener and forward the characteristic value passed in the event to libqaul to be serialized as protobufs and displayed to the user.
Qaul BLE communication architecture

Deliverables :

  • Creating a stable working ble_module for Linux including fixing, and testing the current prototype.
  • Establish communication of the ble_module with libqaul.
  • Make sure the Linux Bluetooth code is interoperable with Android and iOS Bluetooth modules.
  • Try to optimize the Bluetooth module for better stability and connection.

Concluding Thoughts:

I have always been inspired by the idea of a world built on free and decentralized architecture. When I read the project’s description, I felt motivated to join a community dedicated to achieving borderless, decentralized communication that rivals established centralized applications.

I would like to thank my mentors, Mathias Jud and Brenodt, for guiding me through the project and helping me understand the internal workings of the applications. I am eager to contribute to the project with great enthusiasm.