Harness CF Flutter SDK

Overview


Harness is a feature management platform that helps teams to build better software and to test features quicker.


Setup

To install SDK, declare a dependency to project's pubspec.yaml file:

ff_flutter_client_sdk: ^1.0.1

Then, you may import package to your project

import 'package:ff_flutter_client_sdk/CfClient.dart';

After this step, the SDK elements, primarily CfClient, should be accessible in main application.

Initialization

CfClient is base class that provides all thefeatures of SDK.

final conf = CfConfigurationBuilder()
    .setStreamEnabled(true)
    .setPollingInterval(60) //time in seconds (minimum value is 60)
    .build();
final target = CfTargetBuilder().setIdentifier(name).build();

final res = await CfClient.initialize(apiKey, conf, target);

target represents a desired target for which we want features to be evaluated.

"YOUR_API_KEY" is an authentication key, needed for access to Harness services.

Your Harness SDK is now initialized. Congratulations!!!

Public API Methods

The Public API exposes a few methods that you can utilize:

  • static Future<InitializationResult> initialize(String apiKey, CfConfiguration configuration, CfTarget target)

  • static Future<bool> boolVariation(String evaluationId, bool defaultValue)

  • static Future<String> stringVariation(String evaluationId, String defaultValue)

  • static Future<double> numberVariation(String evaluationId, double defaultValue)

  • static Future<Map<dynamic, dynamic>> jsonVariation(String evaluationId, Map<dynamic, dynamic> defaultValue)

  • static Future<void> registerEventsListener(CfEventsListener listener)

  • static Future<void> unregisterEventsListener(CfEventsListener listener)

  • static Future<void> destroy()

Fetch evaluation's value

It is possible to fetch a value for a given evaluation. Evaluation is performed based on different type. In case there is no evaluation with provided id, the default value is returned.

Use appropriate method to fetch the desired Evaluation of a certain type.

boolVariation(String evaluationId, bool defaultValue)

//get boolean evaluation
final evaluation = await CfClient.boolVariation("demo_bool_evaluation", false);

numberVariation(String evaluationId, double defaultValue)

//get number evaluation
final numberEvaluation = await CfClient.numberVariation("demo_number_evaluation", 0);

stringVariation(String evaluationId, String defaultValue)

//get string evaluaation
final stringEvaluation = await CfClient.stringVariation("demo_string_evaluation", "default");

jsonVariation(String evaluationId, Map<dynamic, dynamic> defaultValue)

//get json evaluation
final jsonEvaluation = await CfClient.jsonVariation("demo_json_evaluation", {});

Register for events

This method provides a way to register a listener for different events that might be triggered by SDK, indicating specific change in SDK itself.

    CfClient.registerEventsListener((EvaluationResponse, EventType) {
     
    });

Triggered event will have one of the following types.

enum EventType {
    SSE_START,
    SSE_END,
    EVALUATION_POLLING,
    EVALUATION_CHANGE
}

Each type will return a corresponding value as shown in the table below.

| EventType          | Returns                  |
| :----------------  | :-----------------------:|
| SSE_START          | null                     |
| SSE_END            | null                     |
| EVALUATION_POLLING | List<EvaluationResponse> |
| EVALUATION_CHANGE  | EvaluationResponse       |

Visit documentation for complete list of possible types and values they provide.

To avoid unexpected behaviour, when listener is not needed anymore, a caller should call CfClient.unregisterEventsListener(eventsListener) This way the sdk will remove desired listener from internal list.

Shutting down the SDK

To avoid potential memory leak, when SDK is no longer needed (when the app is closed, for example), a caller should call this method

CfClient.destroy()

Libraries

ff_flutter_client_sdk