flipt-client-dart

Flipt Client Dart

The flipt-client-dart library contains the Dart source code for the Flipt client-side evaluation client.

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  flipt_client: ^0.1.0

Then run dart pub get to install the package.

How Does It Work?

The flipt-client-dart library is a wrapper around the flipt-engine-ffi library.

All evaluation happens within the SDK, using the shared library built from the flipt-engine-ffi library.

Because the evaluation happens within the SDK, the SDKs can be used in environments where the Flipt server is not available or reachable after the initial data is fetched.

Data Fetching

Upon instantiation, the flipt-client-dart library will fetch the flag state from the Flipt server and store it in memory. This means that the first time you use the SDK, it will make a request to the Flipt server.

Polling (Default)

By default, the SDK will poll the Flipt server for new flag state at a regular interval. This interval can be configured using the updateInterval option when constructing a client. The default interval is 120 seconds.

Streaming (Flipt Cloud Only)

Flipt Cloud users can use the streaming fetch method to stream flag state changes from the Flipt server to the SDK.

When in streaming mode, the SDK will connect to the Flipt server and open a persistent connection that will remain open until the client is closed. The SDK will then receive flag state changes in real-time.

Supported Architectures

This SDK currently supports the following OSes/architectures:

• Linux x86_64
• Linux arm64
• MacOS x86_64
• MacOS arm64
• Windows x86_64

Important

This SDK currently only supports desktop platforms (MacOS, Linux, Windows). We are working on adding support for mobile platforms such as iOS and Android.

Usage

import 'package:flipt_client/flipt_client.dart';

void main() {
  // Initialize the client
  final client = FliptEvaluationClient(
    'default',
    Options.withClientToken(
      'your-token',
      url: 'http://localhost:8080',
    ),
  );

  // Evaluate a variant flag
  final result = client.evaluateVariant(
    flagKey: 'flag1',
    entityId: 'someentity',
    context: {'fizz': 'buzz'},
  );

  print('Variant: ${result.variantKey}');

  // Evaluate a boolean flag
  final result = client.evaluateBoolean(
    flagKey: 'flag2',
    entityId: 'user123',
    context: {'key': 'value'},
  );

  print('Enabled: ${result.enabled}');

  // Don't forget to close the client when you're done
  client.close();
}

Authentication

The FliptEvaluationClient supports the following authentication strategies:

• No Authentication (default)
• Client Token Authentication
• JWT Authentication

Development

To generate the JSON serialization code, run:

dart run build_runner build --delete-conflicting-outputs

Contributing

Contributions are welcome! Please feel free to open an issue or submit a Pull Request.

License

This project is licensed under the MIT License.