Impressions after migration

After migrating to Feature Experimentation from Full Stack Experimentation (Legacy), if you are running A/B tests and use the getEnabledFeatures SDK method, action is required to ensure impressions are counted accurately after migrating.

In Full Stack Experimentation (Legacy), there are two different types of experiments you can run:

Optimizely triggers an impression for a user that qualifies for a running experiment when you call the activate method for A/B tests or the isFeatureEnabled or getEnabledFeatures methods for feature tests, respectively.

Calling the isFeatureEnabled or getEnabledFeatures methods only return variables and send impressions for feature tests. Impressions are not sent for A/B tests with these methods.

In Feature Experimentation, experiments are flag rules built on a feature flag. More details are in the Simplified data model documentation.

Optimizely Experimentation triggers an impression when a user is exposed to a flag variation as part of an Optimizely experiment. The legacy methods listed above (activate, isFeatureEnabled, getEnabledFeatures) are still fully supported after you migrate a project to Feature Experimentation.

If you use both the activate and getEnabledFeatures methods in an A/B test, you will see an increase in the number of impressions that Optimizely triggers after migrating.

After migrating to Feature Experimentation, your A/B test from Full Stack Experimentation (Legacy) becomes an A/B test flag rule under its own feature flag. The activate method will still return the appropriate variation for a converted A/B test flag rule and trigger an impression as expected without any needed code changes. For information on migrating A/B tests, see Migrate legacy A/B test.

However, because an A/B test is now a flag rule built on a flag in Feature Experimentation, it is now included in the getEnabledFeatures method after migrating. The getEnabledFeatures method will return variations and trigger impressions for the A/B test flag rule.

Including a converted A/B test flag rule in both the activate and getEnabledFeatures methods may trigger Optimizely to send more impressions than before migrating.

To ensure you are not unknowingly triggering impressions for converted A/B test flag rules, you should replace the activate and getEnabledFeatures methods with the decide and decideAll methods, respectively.

If you encounter any issues transitioning to the decide API, contact your Customer Success Manager, who will assist you to ensure an effective transition.