Sceleton of scheduler that performs tasks with a parallelism level equals to 1

Scheduler.ps1

$jobName = "SchedulerJOB"
$schedulePath = Join-Path $PSScriptRoot "Schedule.json"

$epoch = Get-Date -Year 1970 -Day 1 -Month 1

function Read-WorkItems()
{
    $json = Get-Content -Path $schedulePath -Raw
    $workItems = (ConvertFrom-Json $json)
    $workItems
}

function Process-WorkItems()
{
    $workItems = Read-WorkItems

    foreach($workItem in $workItems)
    {
        $lastTimeInvoked = $workItem.LastTimeInvoked
        $now = (New-TimeSpan -Start $epoch -End (Get-Date)).TotalSeconds
        $passed = $now - $lastTimeInvoked 

        if($passed -gt $workItem.Interval)
        {
            & $workItem.Script
        }
        else
        {
            & $workItem.Script
        }
    }
}

function Scheduler-Start()
{
	$inteval = New-TimeSpan -Minutes 1
	$trigger = New-JobTrigger -Once -At ([DateTime]::UtcNow) -RepetitionInterval $inteval -RepeatIndefinitely

	Register-ScheduledJob -Name $jobName -ScriptBlock {Process-WorkItems} -Trigger $trigger
}

function Scheduler-Stop()
{
	 Unregister-ScheduledJob -Name $jobName
}