functions/Watch-DbaXESession.ps1

function Watch-DbaXESession {
 <#
    .SYNOPSIS
    Watch live XEvent Data as it happens
 
    .DESCRIPTION
    Watch live XEvent Data as it happens - this command runs until you kill the PowerShell session or Ctrl-C.
     
    Thanks to Dave Mason (@BeginTry) for some straightforward code samples https://itsalljustelectrons.blogspot.be/2017/01/SQL-Server-Extended-Event-Handling-Via-Powershell.html
 
    .PARAMETER SqlInstance
    The SQL Instances that you're connecting to.
 
    .PARAMETER SqlCredential
    Credential object used to connect to the SQL Server as a different user
 
    .PARAMETER Session
    Only return a specific session. This parameter is auto-populated.
         
    .PARAMETER Raw
    Returns the Microsoft.SqlServer.XEvent.Linq.QueryableXEventData enumeration object
     
    .PARAMETER SessionObject
    Internal parameter
     
    .PARAMETER EnableException
    By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
    This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
    Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
     
    .NOTES
    Tags: Xevent
    Website: https://dbatools.io
    Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
    License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
    .LINK
    https://dbatools.io/Watch-DbaXESession
 
    .EXAMPLE
    Watch-DbaXESession -SqlInstance ServerA\sql987 -Session system_health
 
    Shows events for the system_health session as it happens
 
    .EXAMPLE
    Get-DbaXESession -SqlInstance sql2016 -Session system_health | Watch-DbaXESession | Select -ExpandProperty Fields
     
    Also shows events for the system_health session as it happens and expands the Fields property. Looks a bit like this
     
    Name Type Value
    ---- ---- -----
    id System.UInt32 0
    timestamp System.UInt64 0
    process_utilization System.UInt32 0
    system_idle System.UInt32 99
    user_mode_time System.UInt64 8906250
    kernel_mode_time System.UInt64 468750
    page_faults System.UInt32 60
    working_set_delta System.Int64 0
    memory_utilization System.UInt32 99
 
#>

    [CmdletBinding(DefaultParameterSetName="Default")]
    param (
        [parameter(ValueFromPipeline, ParameterSetName = "instance", Mandatory)]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstanceParameter]$SqlInstance,
        [PSCredential]$SqlCredential,
        [string]$Session,
        [parameter(ValueFromPipeline, ParameterSetName = "piped", Mandatory)]
        [Microsoft.SqlServer.Management.XEvent.Session]$SessionObject,
        [switch]$Raw,
        [switch][Alias('Silent')]$EnableException
    )
    process {
        if (-not $SqlInstance) {
            $server = $SessionObject.Parent
        }
        else {
            try {
                Write-Message -Level Verbose -Message "Connecting to $SqlInstance"
                $server = Connect-SqlInstance -SqlInstance $SqlInstance -SqlCredential $SqlCredential -MinimumVersion 11
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $SqlInstance -Continue
            }
            $SqlConn = $server.ConnectionContext.SqlConnectionObject
            $SqlStoreConnection = New-Object Microsoft.SqlServer.Management.Sdk.Sfc.SqlStoreConnection $SqlConn
            $XEStore = New-Object  Microsoft.SqlServer.Management.XEvent.XEStore $SqlStoreConnection
            Write-Message -Level Verbose -Message "Getting XEvents Sessions on $SqlInstance."
            $SessionObject = $XEStore.sessions | Where-Object Name -eq $Session | Select-Object -First 1
        }
        
        if ($SessionObject) {
            try {
                $xevent = New-Object -TypeName Microsoft.SqlServer.XEvent.Linq.QueryableXEventData(
                    ($server.ConnectionContext.ConnectionString),
                    ($SessionObject.Name),
                    [Microsoft.SqlServer.XEvent.Linq.EventStreamSourceOptions]::EventStream,
                    [Microsoft.SqlServer.XEvent.Linq.EventStreamCacheOptions]::DoNotCache
                )
                
                if ($raw) {
                    foreach ($row in $xevent) {
                        $row
                    }
                }
                else {
                    # make it pretty
                    foreach ($row in $xevent) {
                        Select-DefaultView -InputObject $row -Property Name, Timestamp, Fields, Actions
                    }
                }
            }
            catch {
                Stop-Function -Message "Failure" -ErrorRecord $_ -Target $session
            }
            finally {
                if ($xevent -is [IDisposable]) {
                    $xevent.Dispose()
                }
            }
        }
        else {
            Stop-Function -Message "Session not found" -Target $session
        }
    }
}