# Observe VPN Related Events

The **VPN SDK** on both mobile platforms provides an observer interface that can be implemented in order to handle any events that occur from the client.\
\
The **VPN SDK** for macOS and Windows provides a unified connection status event, offering real-time updates.

{% tabs %}
{% tab title="iOS" %}
The supported events that can be implemented are:

**Status/Configuration Events**

| Property           | Description                                                              |
| ------------------ | ------------------------------------------------------------------------ |
| serverWillChange   | The server defined in the client's `configuration` is about to change.   |
| serverDidChange    | The server defined in the client's `configuration` did change.           |
| protocolWillChange | The protocol defined in the client's `configuration` is about to change. |
| protocolDidChange  | The protocol defined in the client's `configuration` did change.         |

**Connection Events**

| Property                 | Description                                                       |
| ------------------------ | ----------------------------------------------------------------- |
| connectionWillBegin      | The connection to the VPN server is about to start connecting.    |
| connectionDidBegin       | The connection to the VPN server did start connecting.            |
| connectionWillReconnect  | The connection to the VPN server is about to attempt to reconnect |
| connectionSucceeded      | The connection to the VPN server was successful.                  |
| connectionFailed         | The connection to the VPN server failed with `error`.             |
| connectionWillDisconnect | The connection to the VPN server is about to disconnect.          |
| connectionDidDisconnect  | The connection to the VPN server did disconnect.                  |

**Miscellaneous Events**

|                        |                                                                                                                                                                                              |
| ---------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| profileFailedToInstall | <p>The iOS VPN profile failed to install and returned with <code>error</code>.</p><p>Called on <code>connect(withConfiguration:completion:)</code> if the VPN pop-up fails or is denied.</p> |
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{% tab title="Android" %}
To subscribe to observing connection state events, use the `subscribeToConnectionState` method. An identifier of the subscription and an instance of a class that implements the `ConnectionStateSubscriber` interface must be passed in. This class will be notified of changes to the connection state when the connection traverses between `DISCONNECTED`, `CONNECTING`, `CONNECTED` and `ERROR` states.

#### **Setting Up A Subscription** <a href="#setting-up-a-subscription" id="setting-up-a-subscription"></a>

To setup the subscription, call the `subscribeToConnectionState` method as so:

```kotlin
val subscriptionId = UUID.randomUUID().toString()
val subscriber = object : ConnectionStateSubscriber {
    override fun onStateChanged(newState: SudoVPNState) {
        when (newState) {
            SudoVPNState.CONNECTED -> {
                // Handle change in connection state
            }
            SudoVPNState.CONNECTING -> {
                // Handle change in connection state
            }
            SudoVPNState.DISCONNECTED -> {
                // Handle change in connection state
            }
            SudoVPNState.ERROR -> {
                // Handle change in connection state
            }
        }
    }
}
launch {
    try {
        sudoVPNClient.subscribeToConnectionState(
            subscriptionId,
            subscriber
        )
    } catch (e: SudoVPNException) {
        // Handle/notify the user of exception
    }
}
```

#### Cancelling A Subscription

To cancel a subscription, use the `unsubscribeFromConnectionState` or `unsubscribeAll` method. For example:

```kotlin
val subscriptionId = // From where the subscription was set up
launch {
    try {
        sudoVPNClient.unsubscribeFromConnectionState(subscriptionId)
        // or
        sudoVPNClient.unsubscribeAll()
    } catch (e: SudoVPNException) {
        // Handle/notify the user of exception
    }
}
```

This will ensure that the subscription is cancelled and system resources are freed.
{% endtab %}

{% tab title="Typescript" %}
To subscribe to observing connection state events, use the `subscribe` method. An identifier of the subscription and a function that accepts the `SudoVPNConnectionStatus` as a parameter must be passed in. This function will be notified of changes to the connection state when the connection traverses between states.

Valid States:\
`disconnected` \
`disconnecting` \
`connecting` \
`connected` \
`error` \
`unknown`&#x20;

#### **Setting Up A Subscription** <a href="#setting-up-a-subscription" id="setting-up-a-subscription"></a>

To setup the subscription, call the `subscribe` method as so:

```typescript
const subscriptionId = uuid() //unique id to identify the subscription
const subscriber: (status: SudoVPNConnectionStatus) => void = (status) => {
    // ...
}

const subscribeResult = await sudoVpnClient.subscribe(subscriptionId, subscriber)
```

#### Cancelling A Subscription

To cancel a subscription, use the `unsubscribe` or `unsubscribeAll` method. For example:

```typescript
const subscriptionId = // From where the subscription was set up

sudoVpnClient.unsubscribe(subscriptionId)
// or
sudoVpnClient.unsubscribeAll()    
```

This will ensure that the subscription is cancelled and system resources are freed.
{% endtab %}
{% endtabs %}