Overview

ABC server SDKs enable you to run experiments and check feature flags locally on your server. Generally, using the ABC server SDKs involves three steps, as illustrated in the diagram below:

1. Initialization

Upon the startup of your application server, you need to initialize the ABC SDK with your project ID and API access key. The SDK then sends a request to the nearest of our globally deployed configuration servers to fetch necessary configurations, such as experiment allocations and rules. These configurations are essential for evaluating experiments and feature flags. After initialization, the server SDK polls ABC config servers for configuration updates every 3 seconds and stores them locally to ensure rapid result evaluation.

2. Evaluating Experiments and Feature Flags

When the customer code calls the ABC SDK via the getExperiment or getFeatureFlag API, the SDK uses the locally stored configurations to calculate the experiment and feature flag results. As all evaluations occur locally, the latency is minimal.

3. Logging Experiment Assignment Exposure

For experiments and feature flags with enabled experimentation, we offer two methods of logging exposures. Firstly, the SDK will automatically log exposures when you call the getExperiment or getFeatureFlag APIs. Secondly, in certain scenarios where you need to log exposures manually at a later time, we provide a standalone API, LogExperimentExposure. In both methods, the exposures are accumulated locally and periodically flushed to the message queue.

FAQs

Where does the evaluation for the ABC server SDK occur?

All evaluation logic occurs within the SDK.

What is the overall latency for the APIs of the ABC server SDK?

As the evaluation occurs within the SDK using configurations stored in the local cache, the latency for evaluation is extremely low.

How long does it take for my update to reach the users?

The update delivery time consists of two parts: the time taken to deliver the update from the DB to our global config servers, and the time taken for the updates to sync to the ABC SDK via its periodic poll. The total delay would be around 15 seconds.

How does ABC ensure system reliability?

ABC config servers are globally deployed across multiple regions and can auto-scale to handle traffic spikes.