# Local AVSession Overview

## Interaction Process

For a local AVSession, the data sources are on the local device. The figure below illustrates the interaction process.

![Local AVSession Interaction Process](figures/local-avsession-interaction-process.png)

This process involves two roles: provider and controller.

In the local AVSession, the provider exchanges information with the controller through AVSessionManager.

1. The provider creates an **AVSession** object through AVSessionManager.

2. Through the **AVSession** object, the provider sets session metadata (such as the asset ID, title, and duration) and playback attributes (such as the playback state, speed, and position).

3. The controller creates an **AVSessionController** object through AVSessionManager.

4. Through the **AVSessionController** object, the controller listens for changes of the session metadata and playback attributes.

5. Through the **AVSessionController** object, the controller sends control commands to the **AVSession** object.

6. Through the **AVSession** object, the provider listens for the control commands, for example, play, playNext, fastForward, and setSpeed, from the controller.

## AVSessionManager

AVSessionManager provides the capability of managing sessions. It can create an **AVSession** object, create an **AVSessionController** object, send control commands, and listen for session state changes.

Unlike the **AVSession** and **AVSessionController** objects, AVSessionManager is not a specific object, but the root namespace of AVSessions. You can import AVSessionManager as follows:

```ts
import AVSessionManager from '@ohos.multimedia.avsession';
```

All the APIs in the root namespace can be used as APIs of AVSessionManager.

The code snippet below shows how the provider creates an **AVSession** object by using AVSessionManager:

```ts
// Create an AVSession object.
async createSession() {
  let session: AVSessionManager.AVSession = await AVSessionManager.createAVSession(this.context, 'SESSION_NAME', 'audio');
  console.info(`session create done : sessionId : ${session.sessionId}`);
}
```

The code snippet below shows how the controller creates an **AVSessionController** object by using AVSessionManager:

```ts
// Create an AVSessionController object.
async createController() {
  // Obtain the descriptors of all live AVSession objects.
  let descriptorsArray: Array<Readonly<AVSessionManager.AVSessionDescriptor>> = await AVSessionManager.getAllSessionDescriptors();
  if (descriptorsArray.length > 0) {
    // For demonstration, the session ID of the first descriptor is used to create the AVSessionController object.
    let sessionId: string = descriptorsArray[0].sessionId;
    let avSessionController: AVSessionManager.AVSessionController = await AVSessionManager.createController(sessionId);
    console.info(`controller create done : sessionId : ${avSessionController.sessionId}`);
  }
}
```

For more information about AVSessionManager APIs, see [API Reference](../reference/apis/js-apis-avsession.md).