Storage Service

The SDK operates in a stateless mode by default, meaning each get_flag call triggers a fresh evaluation of the flag against the current user context.

To optimize performance and maintain consistency, you can implement a custom storage mechanism by passing a storage parameter during initialization. This allows you to persist feature flag decisions in your preferred database system (like Redis, MongoDB, or any other data store).

Key benefits of implementing storage:

1. Improved performance by caching decisions
2. Consistent user experience across sessions
3. Reduced load on your application

The storage mechanism ensures that once a decision is made for a user, it remains consistent even if campaign settings are modified in the VWO Application. This is particularly useful for maintaining a stable user experience during A/B tests and feature rollouts.

How to Implement a Storage Service

Storage Service is optional while instantiating the VWO SDK. However, to ensure sticky variation assignments, we recommend implementing it.

Usage

class StorageConnector
  def get(feature_key, user_id)
    # Return stored data based on feature_key and user_id
  end

  def set(data)
    # Store data using data[:feature_key] and data[:user_id]
  end
end

vwo_client = VWO.init({
    account_id: '123456',
    sdk_key: '32-alpha-numeric-sdk-key',
    storage: StorageConnector.new
})

Storage Service should expose two methods: get and set. These methods are used by VWO whenever there is a need to read or write from the storage service.