1# ServiceAbility Lifecycle
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4You can implement lifecycle callbacks (as described in the table below) in **service.js** or **service.ets**.
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7**Table 1** ServiceAbility lifecycle callbacks
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9| API| Description|
10| -------- | -------- |
11| onStart(): void | Called to initialize a ServiceAbility when the ServiceAbility is being created. This callback is invoked only once in the entire lifecycle of a ServiceAbility.|
12| onCommand(want: Want, startId: number): void | Called every time a ServiceAbility is started on the client. You can collect calling statistics and perform initialization operations in this callback.|
13| onConnect(want: Want): rpc.RemoteObject | Called when the ServiceAbility is connected.|
14| onDisconnect(want: Want): void | Called when the connection to the ServiceAbility is disconnected.|
15| onStop(): void | Called when the ServiceAbility is being destroyed. You should override this callback for your ServiceAbility to clear its resources, such as threads and registered listeners.|
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