> Currently, the **ContinuationManager** module is not available for application development. Its APIs are mainly used to start the device selection module.
## When to Use
Users are using two or more devices to experience an all-scenario, multi-device lifestyle. Each type of device has its unique advantages and disadvantages specific to scenarios. The ability continuation capability breaks boundaries of devices and enables multi-device collaboration, achieving precise control, universal coordination, and seamless hops of user applications.
As the entry of the ability continuation capability, **continuationManager** is used to start the device selection module for the user to select the target device. After a device is selected, information about the selected device is returned to the user. The user can then initiate cross-device continuation or collaboration based on the device information.
| register(callback: AsyncCallback\<number>): void | Registers the continuation management service and obtains a token. This API does not involve any filter parameters and uses an asynchronous callback to return the result.|
| register(options: ContinuationExtraParams, callback: AsyncCallback\<number>): void | Registers the continuation management service and obtains a token. This API uses an asynchronous callback to return the result.|
| register(options?: ContinuationExtraParams): Promise\<number> | Registers the continuation management service and obtains a token. This API uses a promise to return the result.|
| on(type: "deviceConnect", token: number, callback: Callback\<Array\<ContinuationResult>>): void | Subscribes to device connection events. This API uses an asynchronous callback to return the result.|
| on(type: "deviceDisconnect", token: number, callback: Callback\<Array\<string>>): void | Subscribes to device disconnection events. This API uses an asynchronous callback to return the result.|
| startDeviceManager(token: number, callback: AsyncCallback\<void>): void | Starts the device selection module to show the list of available devices. This API does not involve any filter parameters and uses an asynchronous callback to return the result.|
| startDeviceManager(token: number, options: ContinuationExtraParams, callback: AsyncCallback\<void>): void | Starts the device selection module to show the list of available devices. This API uses an asynchronous callback to return the result.|
| startDeviceManager(token: number, options?: ContinuationExtraParams): Promise\<void> | Starts the device selection module to show the list of available devices. This API uses a promise to return the result.|
| updateConnectStatus(token: number, deviceId: string, status: DeviceConnectState, callback: AsyncCallback\<void>): void | Instructs the device selection module to update the device connection state. This API uses an asynchronous callback to return the result.|
| updateConnectStatus(token: number, deviceId: string, status: DeviceConnectState): Promise\<void> | Instructs the device selection module to update the device connection state. This API uses a promise to return the result.|
| unregister(token: number, callback: AsyncCallback\<void>): void | Deregisters the continuation management service. This API uses an asynchronous callback to return the result.|
| unregister(token: number): Promise\<void> | Deregisters the continuation management service. This API uses a promise to return the result.|
## How to Develop
1. Import the **continuationManager** module.
```ts
import continuationManager from '@ohos.continuation.continuationManager';
```
2. Apply for permissions required for cross-device continuation or collaboration operations.
The permission application operation varies according to the ability model in use. In the FA mode, add the required permission in the `config.json` file, as follows:
```json
{
"module": {
"reqPermissions": [
{
"name": "ohos.permission.DISTRIBUTED_DATASYNC"
}
]
}
}
```
This permission must also be granted by the user through a dialog box when the application is started for the first time. The sample code is as follows:
```ts
import abilityAccessCtrl from "@ohos.abilityAccessCtrl";
import bundle from '@ohos.bundle';
async function requestPermission() {
let permissions: Array<string> = [
"ohos.permission.DISTRIBUTED_DATASYNC"
];
let needGrantPermission: boolean = false;
let atManager: abilityAccessCtrl.AtManager = abilityAccessCtrl.createAtManager();
let applicationInfo = await bundle.getApplicationInfo('ohos.samples.etsDemo', 0, 100);
for (let i = 0; i < permissions.length; i++) {
let result = await atManager.verifyAccessToken(applicationInfo.accessTokenId, permissions[i]);
// Check whether the permission is granted.
if (result == abilityAccessCtrl.GrantStatus.PERMISSION_GRANTED) {
needGrantPermission = true;
break;
}
}
// If the permission is not granted, call requestPermissionsFromUser to apply for the permission.
3. Register the continuation management service and obtain a token.
The sample code is as follows:
```ts
let token: number = -1; // Used to save the token returned after the registration. The token will be used when listening for device connection/disconnection events, starting the device selection module, and updating the device connection state.
4. Listen for the device connection/disconnection state.
The sample code is as follows:
```ts
let remoteDeviceId: string = ""; // Used to save the information about the remote device selected by the user, which will be used for cross-device continuation or collaboration.
// The token parameter is the token obtained during the registration.
The preceding multi-device collaboration operation is performed across devices in the stage model. For details about this operation in the FA model, see [Page Ability Development](https://gitee.com/openharmony/docs/blob/master/en/application-dev/ability/fa-pageability.md).
You can also instruct the device selection module to update the device connection state. The sample code is as follows:
```ts
// Set the device connection state.
let deviceConnectStatus: continuationManager.DeviceConnectState = continuationManager.DeviceConnectState.CONNECTED;
// The token parameter is the token obtained during the registration, and the remoteDeviceId parameter is the remoteDeviceId obtained.
6. If you do not need to perform cross-device migration or collaboration operations, you can deregister the continuation management service, by passing the token obtained during the registration.
The sample code is as follows:
```ts
// The token parameter is the token obtained during the registration.
