Flower Android Example (TensorFlowLite)¶

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This example demonstrates a federated learning setup with Android clients in a background thread. The training on Android is done on a CIFAR10 dataset using TensorFlow Lite. The setup is as follows:

  • The CIFAR10 dataset is randomly split across 10 clients. Each Android client holds a local dataset of 5000 training examples and 1000 test examples.

  • The FL server runs in Python but all the clients run on Android.

  • We use a strategy called FedAvgAndroid for this example.

  • The strategy is vanilla FedAvg with a custom serialization and deserialization to handle the Bytebuffers sent from Android clients to Python server.

The background thread is established via the WorkManager library of Android, thus, it will run comfortably on Android Versions from 8 to 13.

Project Setup¶

Start by cloning the example project. We prepared a single-line command that you can copy into your shell which will checkout the example for you:

git clone --depth=1 https://github.com/adap/flower.git && mv flower/examples/android . && rm -rf flower && cd android

Installing Dependencies¶

Project dependencies (such as tensorflow and flwr) are defined in pyproject.toml and requirements.txt. We recommend Poetry to install those dependencies and manage your virtual environment (Poetry installation) or pip, but feel free to use a different way of installing dependencies and managing virtual environments if you have other preferences.

Poetry¶

poetry install
poetry shell

Poetry will install all your dependencies in a newly created virtual environment. To verify that everything works correctly you can run the following command:

poetry run python3 -c "import flwr"

If you don’t see any errors you’re good to go!

pip¶

Write the command below in your terminal to install the dependencies according to the configuration file requirements.txt.

pip install -r requirements.txt

Run Federated Learning on Android Devices¶

The included run.sh will start the Flower server (using server.py). You can simply start it in a terminal as follows:

poetry run ./run.sh

Download and install the flwr_android_client.apk on each Android device/emulator. The server currently expects a minimum of 4 Android clients, but it can be changed in the server.py.

When the Android app runs, add the client ID (between 1-10), the IP and port of your server, and press Start. This will load the local CIFAR10 dataset in memory, establish connection with the server, and start the federated training. To abort the federated learning process, press Stop. You can clear and refresh the log messages by pressing Clear and Refresh buttons respectively.