Initialize Flutter SDK

The initializeClient method initializes the Flutter SDK and instantiates an instance of the Optimizely Feature Experimentation SDK class, which exposes API methods like the CreateUserContext method. Each client corresponds to the datafile that represents the state of a project for an environment. The datafile is accessible through OptimizelyConfig.

Version

2.0.0 or higher

Description

The constructor accepts a configuration object to configure Optimizely Feature Experimentation.

Some parameters are optional because the Flutter SDK provides a default implementation, but you may want to override these for your production environments. For example, you can set up event options to manage network calls and datafile handler parameters to set up the datafile download path or interval.

Parameters

start method parameters:

The following settings are optionally configurable when the Flutter SDK is initialized:

• ODP SegmentsCache size – segmentsCacheSize
  • Default – 100
  • Set to 0 to disable caching.
• ODP SegmentsCache timeout (in seconds) – segmentsCacheTimeoutInSecs
  • Default – 600 secs (10 minutes)
  • Set to 0 to disable timeout (never expires).
• ODP enable – disableOdp
  • Default – false (enabled)
  • When disableOdp is set to true, the Flutter SDK will disable ODP-related features. The Flutter SDK still creates and manages VUID regardless of this flag and supports VUID-based decisions. See anonymous users.
  • The Flutter SDK returns or logs an odpNotEnabled error when ODP is disabled and its features are requested.

// You must configure Real-Time Segments for Feature Experimentation before using the following methods.
class SDKSettings {
  // The maximum size of audience segments cache (optional. default = 100). Set to zero to disable caching.
  final int segmentsCacheSize;
  // The timeout in seconds of audience segments cache (optional. default = 600). Set to zero to disable timeout.
  final int segmentsCacheTimeoutInSecs;
  // The timeout in seconds of ODP segment fetch (optional. default = 10) - OS default timeout will be used if this is set to zero.
  final int timeoutForSegmentFetchInSecs;
  // The timeout in seconds of ODP event dispatch (optional. default = 10) - OS default timeout will be used if this is set to zero.
  final int timeoutForOdpEventInSecs;
  // Set this flag to true (default = false) to disable ODP features
  final bool disableOdp;
}

Returns

Instantiates an instance of the Optimizely Feature Experimentation class.

Customize ODPManager

The Flutter SDK enables the Real-Time Segments for Feature Experimentation methods by default. But, the methods do nothing unless you have enabled and configured Real-Time Segments for Feature Experimentation.

If necessary, to disable Real-Time Segments for Feature Experimentation altogether, set disableOdp to true.

You can provide segmentsCacheSize and segmentsCacheTimeoutInSecs timeout by passing these values when initializing the Flutter SDK.

const odpSettings = SDKSettings( 
   segmentsCacheSize: 1000, 
   segmentsCacheTimeoutInSecs: 30 * 60, 
   disableOdp: false); 
var flutterSDK = OptimizelyFlutterSdk("<Your_SDK_Key>", sdkSettings: odpSettings); 
var response = await flutterSDK.initializeClient(); 

Examples

You do not need to manage the datafile directly in the Flutter SDK. The SDK includes a datafile manager that provides support for datafile polling to automatically update the datafile on a regular interval while the application is in the foreground.

To use it:

1. Create a OptimizelyFlutterSdk by supplying your SDK Key and optional configuration settings. You can find the SDK key in Settings > Environments of a Feature Experimentation project.

2. To start the client synchronously and use the initializeClient method to instantiate a client:

// Initializing Optimizely Client
var flutterSDK = OptimizelyFlutterSdk("<Your_SDK_Key>");
var response = await flutterSDK.initializeClient();
// flag decision
var user = await flutterSDK.createUserContext(userId: "<User_ID>");
var decideResponse = await user!.decide("<Flag_Key>");

Use initialization

To instantiate the Optimizely client: synchronous. This method pings the Optimizely Feature Experimentation servers for a new datafile during initialization.

During initialization, your app requests the newest datafile from the CDN servers. Requesting the newest datafile ensures that your app uses the latest project settings. It also means your app cannot instantiate a client until it downloads a new datafile, discovers the datafile has not changed, or the request times out.

Initializing a client synchronously causes the manager to first attempt to download the newest datafile. The network activity causes an initialization to take longer to complete.

If the network request returns an error, such as when network connectivity is unreliable or if the manager discovers that the cached datafile is identical to the newest datafile, the Optimizely Feature Experimentation manager searches for a cached datafile. If one is available, the manager uses the datafile to complete the client initialization; otherwise initialization fails. If the manager discovers there is an updated datafile that differs from the cached datafile, the manager downloads the new datafile and uses it to initialize the client.

To initialize an OptimizelyClient object, call flutterSDK.initializeClient().

Configure datafile polling

Datafile polling is the process of checking for and downloading a new datafile. After the manager tries to pull the latest datafile from the CDN servers, the Optimizely manager periodically checks for and pulls a new datafile at the time interval you set during its initialization.

By default, datafile polling is enabled. You can set a non-zero interval value for increasing or decreasing the time period of polling interval. This value is the number of seconds the manager waits between datafile polling attempts.

// Datafile update interval can be configured when the SDK is configured
// Background datafile update is disabled if periodicDownloadInterval is zero
var flutterSDK = OptimizelyFlutterSdk("<Your_SDK_Key>", datafilePeriodicDownloadInterval: 15 * 60);
// every 15 minutes

Usage notes

• The minimum polling interval is 15 minutes while the app is open. You cannot set a shorter polling interval.

• The Optimizely manager only checks for new datafiles when the SDK is active, and the app runs on iOS, tvOS, or Android.

• The Flutter SDK automatically updates when it detects a new datafile to ensure you are always working with the latest datafile. If you want to receive a notification when the project updates, register for a datafile change through the datafile change notification listener. You can also register for datafile change notifications using the UpdateConfigNotification method.

flutterSDK.addConfigUpdateNotificationListener((msg) {
      print("got datafile change");
    });

Dispose of the client

For effective resource management with the Optimizely Flutter SDK, you must properly close the Optimizely client instance when it is no longer needed. This is done by calling .close.

The .close() method ensures that the processes and queues associated with the instance are properly released. This is essential for preventing memory leaks and ensuring that the application runs efficiently, especially in environments where resources are limited or in applications that create and dispose of many instances over their lifecycle.

See Close Optimizely Feature Experimentation Flutter SDK on application exit.

More sample code

// Initializing OptimizelyClient without optional parameters
var flutterSDK = OptimizelyFlutterSdk("<Your_SDK_Key>");
var response = await flutterSDK.initializeClient();
// flag decision
var user = await flutterSDK.createUserContext(userId: "<User_ID>");
var decideResponse = await user!.decide("<Flag_Key>");
 
// Initializing OptimizelyClient with optional datafilePeriodicDownloadInterval
var flutterSDK =
    OptimizelyFlutterSdk(sdkKey, datafilePeriodicDownloadInterval: 16 * 60);
var response = await flutterSDK.initializeClient();
// flag decision
var user = await flutterSDK.createUserContext(userId: "<User_ID>");
var decideResponse = await user!.decide("<Flag_Key>");

Source files

The language and platform source files containing the implementation for Flutter are available on GitHub.