Configure event dispatcher

The Optimizely SDKs make HTTP requests for every impression or conversion that gets triggered. Each SDK has a built-in event dispatcher for handling these events, but we recommend overriding it based on the specifics of your environment.

The Node SDK has an out-of-the-box asynchronous dispatcher. We recommend customizing the event dispatcher you use in production to ensure that you queue and send events in a manner that scales to the volumes handled by your application. Customizing the event dispatcher allows you to handle large event volumes efficiently. or to implement retry logic when a request fails. You can build your dispatcher from scratch or start with the provided dispatcher.

The examples show that to customize the event dispatcher, initialize the Optimizely client (or manager) with an event dispatcher instance. The example is for the 3.0.0 and 3.0.1 SDKs.

// Client with defaultEventDispatcher
// 3.0.0 SDK
const defaultEventDispatcher = require("@optimizely/optimizely-sdk/lib/plugins/event_dispatcher/index.node");

// 3.0.1 SDK and above
const defaultEventDispatcher = require('@optimizely/optimizely-sdk').eventDispatcher;

// Create an Optimizely client with the default event dispatcher
var optimizelyClientWithDefaultDispatcher = optimizely.createInstance({
  datafile,
  eventDispatcher: defaultEventDispatcher
});

The event dispatcher should implement a dispatchEvent function, which takes in three arguments: httpVerb, url, and params, all of which are created by the internal EventBuilder class. In this function, you should send a POST request to the given url using the params as the body of the request (be sure to stringify it to JSON) and {content-type: 'application/json'} in the headers.

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Important

If you are using a custom event dispatcher, do not modify the event payload returned from Optimizely. Modifying this payload will alter your results.