# Host

The automatic variable [\$Host](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_automatic_variables?view=powershell-5.1#host) is of type [PSHost](https://docs.microsoft.com/en-us/dotnet/api/system.management.automation.host.pshost?view=powershellsdk-1.1.0) and represents the current host application for PowerShell.\
Within the context of powerEvents this can either be the Vault *WebServiceExtension* running an extended Host version or your *PowerShell IDE*.

## Syntax

```PowerShell
$Host.Name
```

```{seealso}
For the complete list of properties and methods and for more information see: [PSHost Class](https://docs.microsoft.com/en-us/dotnet/api/system.management.automation.host.pshost?view=powershellsdk-1.1.0).
```

Following properties are always available :

| Type       | Name        | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Access type |
| ---------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- |
| String     | Name        | An identifier for the PowerShell hosting application. Within [event scripts](/event_scripts) this should be *'powerEvents Webservice Extension'*.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | read-only   |
| *PSObject* | PrivateData | Each Host can provide private data that is editable. For example the property [ErrorBackgroundColor](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/get-host?view=powershell-7.1#example-8--set-the-background-color-for-error-messages) that is available in several PowerShell IDEs for changing the background color of error messages.<br>The powerEvents Host allows manipulating the way how Vault users are notified about [Terminating Errors](https://docs.microsoft.com/en-us/powershell/scripting/developer/cmdlet/terminating-errors?view=powershell-7.1) using the {code}`OnTerminatingError` property. | read-write  |

## Remarks

In contrast to your PowerShell IDE the powerEvents Host redirects the written output into the [logfile](<logging:logfile>).\
The format of the output provided by the [Write-Host](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/write-host) cmdlet can be customised within the according [Logging](<logging:powershell ide>) sections.

### Error Notifications

By default the powerEvents host is configured to write to the logfile and display a modal Vault restrictions dialog to notify users [about erroneous](<event_scripts:errors>) event scripts, modules and exceptions that were thrown by registered Vault events.\
The way how users are notified about [terminating errors](https://docs.microsoft.com/en-us/powershell/scripting/developer/cmdlet/terminating-errors) can be changed using the **PrivateData** and its {code}`OnTerminatingError` property that provides all the relevant error details:

```PowerShell
$global:Host.PrivateData.OnTerminatingError = [Action[System.Management.Automation.RuntimeException]] {
	param($exception)
	        $errorType = $exception.GetType().FullName
	        $errorMessage = $exception.Message
	        $errorStackTrace = $exception.ErrorRecord.ScriptStackTrace

	        if($exception.Data['RegisteredEvent'])
	        {
	                $eventScript = $exception.Data['RegisteredEvent'].Script.FullName
	                $vaultEventName = $exception.Data['RegisteredEvent'].Name
	                Write-Host "An unexpected error has occurred in the event script '$eventScript' for Vault event '$vaultEventName'.`r`n$errorType : $errorMessage`r`n$errorStackTrace"
	        }
	        else
	        {
	                Write-Host "An unexpected error has occurred in the script or module '$($exception.ErrorRecord.InvocationInfo.ScriptName)'`r`n$errorType : $errorMessage`r`n$errorStackTrace"
	        }
}
```

### Automatic Script reloading

Changes made in the PowerShell files located in the [Events](<event_scripts:scripts>) or [Modules](<event_scripts:modules>) folder are loaded by the powerEvents Host at *every start*.\
Also when the files are modified while they are loaded, powerEvents **automatically executes them again**. Restarting your application is not required.\
Adding or removing [Scripts](<event_scripts:scripts>) or [Modules](<event_scripts:modules>) also causes powerEvents to automatically reload the whole configuration.\
Keep this functionality in mind when developing new event scripts or saving changes in your PowerShell IDE.\
In order to disable this functionality you can use the global flag {code}`$powerEvents_ReloadPsScripts` in the *Common.psm1* [Module](<event_scripts:modules>):

```PowerShell
$global:powerEvents_ReloadPsScripts = $false
```

After enabling this functionality again, you need to restart the application.