1# Local AVSession Overview 2 3## Interaction Process 4 5For a local AVSession, the data sources are on the local device. The figure below illustrates the interaction process. 6 7 8 9This process involves two roles: provider and controller. 10 11> **NOTE** 12> 13> The controller must be a system application. A third-party application can be a provider. 14 15In the local AVSession, the provider exchanges information with the controller through AVSessionManager. 16 171. The provider creates an **AVSession** object through AVSessionManager. 18 192. 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). 20 213. The controller creates an **AVSessionController** object through AVSessionManager. 22 234. Through the **AVSessionController** object, the controller listens for changes of the session metadata and playback attributes. 24 255. Through the **AVSessionController** object, the controller sends control commands to the **AVSession** object. 26 276. Through the **AVSession** object, the provider listens for the control commands, for example, play, playNext, fastForward, and setSpeed, from the controller. 28 29## AVSessionManager 30 31AVSessionManager 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. 32 33Unlike the **AVSession** and **AVSessionController** objects, AVSessionManager is not a specific object, but the root namespace of AVSessions. You can import AVSessionManager as follows: 34 35```ts 36import AVSessionManager from '@ohos.multimedia.avsession'; 37``` 38 39All the APIs in the root namespace can be used as APIs of AVSessionManager. 40 41The code snippet below shows how the provider creates an **AVSession** object by using AVSessionManager: 42 43```ts 44// Create an AVSession object. 45let context: Context = getContext(this); 46async function createSession() { 47 let session: AVSessionManager.AVSession = await AVSessionManager.createAVSession(context, 'SESSION_NAME', 'audio'); 48 console.info(`session create done : sessionId : ${session.sessionId}`); 49} 50``` 51 52The code snippet below shows how the controller creates an **AVSessionController** object by using AVSessionManager: 53 54```ts 55// Create an AVSessionController object. 56async function createController() { 57 // Obtain the descriptors of all live AVSession objects. 58 let descriptorsArray: Array<AVSessionManager.AVSessionDescriptor> = await AVSessionManager.getAllSessionDescriptors(); 59 if (descriptorsArray.length > 0) { 60 // For demonstration, the session ID of the first descriptor is used to create the AVSessionController object. 61 let sessionId: string = descriptorsArray[0].sessionId; 62 let avSessionController: AVSessionManager.AVSessionController = await AVSessionManager.createController(sessionId); 63 console.info(`controller create done : sessionId : ${avSessionController.sessionId}`); 64 } 65} 66``` 67 68For more information about AVSessionManager APIs, see [API Reference](../reference/apis-avsession-kit/js-apis-avsession.md). 69
