# Frontend API

The following requirements applies to any frontend implementation:

- A frontend MAY do mostly whatever it wants to, including creating threads, opening TCP ports and exposing Mopidy for a group of clients.

- A frontend MUST implement at least one Pykka actor, called the “main actor” from here on.

- The main actor MUST accept two constructor arguments:

  - `config`, which is a dict structure with the entire Mopidy configuration.

  - `core`, which will be an `ActorProxy` for the core actor. This object gives access to the full mopidy.core — Core API.

- It MAY use additional actors to implement whatever it does, and using actors in frontend implementations is encouraged.

- The frontend is enabled if the extension it is part of is enabled. See Extension development for more information.

- The main actor MUST be able to start and stop the frontend when the main actor is started and stopped.

- The frontend MAY require additional config values to be set for it to work.

- Such config values MUST be documented.

- The main actor MUST raise the `mopidy.exceptions.FrontendError` with a descriptive error message if the defined config values are not adequate for the frontend to work properly.

- Any actor which is part of the frontend MAY implement the `mopidy.core.CoreListener` interface to receive notification of the specified events.

## Frontend implementations

See the extension registry.