Evaluation Mode

The Hackle SDK determines which A/B Test variation a user belongs to, whether a Feature Flag is on, and which Remote Config value to use through an evaluation process. Evaluation takes user information and workspace configuration as input and outputs the distribution result.

The Hackle SDK provides two evaluation modes depending on where evaluation is performed. You choose the evaluation mode when initializing the SDK; if you do not configure it, the SDK operates with Local Evaluation.

Local Evaluation

The SDK evaluates directly on the user's device. This is the default evaluation mode.

Remote Evaluation

The SDK looks up results that the Hackle server evaluated in advance.

Differences Between the Two Modes

Category	Local Evaluation	Remote Evaluation
Evaluation location	User's device (SDK)	Hackle server
Reflecting Dashboard changes	On SDK initialization, On SDK fetch	On SDK initialization, When user information is updated
Information used for distribution	Based on user information stored on the device	Based on user information stored on the server
Behavior on a distribution/decision call	The SDK evaluates directly using the stored configuration	Looks up the stored evaluation result
Latency	Evaluates without network communication	Handled without network communication if user information has not changed Communicates with the server to re-evaluate when user information changes
Supported SDKs	All SDKs	Some Client SDKs

In both modes, no network call occurs at the time of the distribution/decision call, so it is processed without any slowdown.

For details, see the SDK Latency document.

Which mode should you choose?

The default evaluation mode is Local Evaluation, and it is suitable in most cases.

• When targeting with information the device already has, such as app version, device OS, or User Properties set on the client

• When you need the distribution result at the moment user information changes, such as the screen right after login

• When you need screen-based targeting, such as with pagePath

Use Remote Evaluation when distribution must be based on user information stored on the Hackle server.

• When you update User Properties from your server using the HTTP API and target with that information

• When you update properties to the Hackle server one time, such as subscription details or membership tier, and target with that information