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Further Reading

Covers advanced topics (different config options and scenarios)

Configuration Options

The following configuration options are available to control the behaviour of the SDK. You can provide options by passing them in when the client is created e.g.

CfClient.Instance.Initialize(apiKey, Config.Builder()
    .ConfigUrl("https://config.ff.harness.io/api/1.0")
    .EventUrl("https://events.ff.harness.io/api/1.0")
    .SetPollingInterval(60)
    .SetStreamEnabled(true)
    .SetAnalyticsEnabled(true)
    .Build());
Name Config Option Description default
baseUrl ConfigUrl("https://config.ff.harness.io/api/1.0") the URL used to fetch feature flag evaluations. You should change this when using the Feature Flag proxy to http://localhost:7000 https://config.ff.harness.io/api/1.0
eventsUrl EventUrl("https://events.ff.harness.io/api/1.0") the URL used to post metrics data to the feature flag service. You should change this when using the Feature Flag proxy to http://localhost:7000 https://events.ff.harness.io/api/1.0
pollInterval SetPollingInterval(60) when running in stream mode, the interval in seconds that we poll for changes. 60
enableStream SetStreamEnabled(true) Enable streaming mode. true
enableAnalytics SetAnalyticsEnabled(true) Enable analytics. Metrics data is posted every 60s true

Anonymous Target

If you do not want a Target to be sent to Harness servers, you can use the isPrivate field.

Target target1 = Target.builder()
                .Identifier("myIdentifier")
                .Name("myName")
                .IsPrivate(true)
                .Attributes(new Dictionary<string, string>(){{"email", "demo@harness.io"}})
                .build();

Logging Configuration

You can configure the logger using Serilog. Add Serilog to your project with the following commands

dotnet add package Serilog

You can then configure the logger to write to the console with debug using the following

// Logger
Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.Console()
    .CreateLogger();

Recommended reading

Feature Flag Concepts

Feature Flag SDK Concepts

Setting up your Feature Flags

Feature Flags Getting Started

Other Variation Types

Bool variation

  • public bool boolVariation(string key, dto.Target target, bool defaultValue)

Number variation

  • public double numberVariation(string key, dto.Target target, double defaultValue)

String variation

  • public string stringVariation(string key, dto.Target target, string defaultValue)

JSON variation

  • public JObject jsonVariation(string key, dto.Target target, JObject defaultValue)

Waiting for Initialization

The user can call WaitForInitialization() to block and wait for the SDK

// Creates instance of a client
var client = new CfClient(API_KEY, Config.Builder().Build());

// Starts authentication and asynchronously wait for initialisation to complete
client.WaitForInitialization();

Connector

This feature allows you to create or use other connectors. Connector is just a proxy to your data. Currently supported connectors:

  • Harness (Used by default)
  • Local (used only in development)
LocalConnector connector = new LocalConnector("local");
client = new CfClient(connector);

Storage

For offline support and asynchronous startup of SDK user should use storage interface. When SDK is used without waiting on async methods, and configuration is provided with file storage, then all flags are loaded from last saved configurations. If there is no flag in a storage then they will be evaluated from defaultValue argument.

FileMapStore fileStore = new FileMapStore("Non-Freemium");
LocalConnector connector = new LocalConnector("local");
client = new CfClient(connector, Config.builder().store(fileStore).build());

Fetch evaluation's value

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

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

Listen on events

Library exposes two events for user to subscribe on getting internal notifications.

Note if WaitForInitialization is used to initialise the SDK, these events must be registered before the WaitForInitialization call. See our getting_started application for an example of this.

client.InitializationCompleted += (sender, e) =>
{
    // fired when authentication is completed and recent configuration is fetched from server
    Console.WriteLine("Notification Initialization Completed");
};
client.EvaluationChanged += (sender, flagIdentifier) =>
{
    // Fired when flag value changes from streaming events.
    Console.WriteLine($"Flag changed for {flagIdentifier}");
};

client.FlagsLoaded += (sender, flagIdentifiers) =>
{
    // Fired once when the SDK has initiailized, and subsquently on each poll if streaming is disabled or has disconnected
    // and fallen back to polling
    foreach (var flagIdentifier in flagIdentifiers)
    {
        Console.WriteLine($"Flags loaded: Flag '{flagIdentifier}");
    }
};

Using feature flags metrics

Metrics API endpoint can be changed like this:

Config.builder()
              .EventUrl("METRICS_API_EVENTS_URL")
              .build();

Otherwise, the default metrics endpoint URL will be used.

Connect to Relay Proxy

When using your Feature Flag SDKs with a Harness Relay Proxy you need to change the default URL. You can pass the URLs in when creating the client. i.e.

        CfClient.Instance.Initialize(apikey, Config.Builder()
            .ConfigUrl("http://localhost:7000")
            .EventUrl("http://localhost:7000")
            .Build());