added Http listener demo

Pwsh/Web/Net.HttpListener Basics.ps1

@@ -49,3 +49,10 @@ $ctx.Response.close()
 
 Log Listener Close
 $listen.Close()
+
+<#
+for async,
+    $task = $httpListener.GetContextAsync()
+    while (-not $task.AsyncWaitHandle.WaitOne(200)) { }
+    $context = $task.GetAwaiter().GetResult()
+#>

Pwsh/Web/Net.HttpListener Part2 Async Cancel.ps1

@@ -0,0 +1,58 @@
+function Log {
+    param(
+        [ArgumentCompletions('Listener', 'Response', 'Context', 'Other', 'Task')]
+        [Parameter()]
+        $Who,
+        [ArgumentCompletions('ctor', 'Close', 'Start', 'End', 'Wait', 'Sleep')]
+        [Parameter()]
+        $What,
+        [Parameter()]
+        $Message = ''
+    )
+    $Color = switch ($Who) {
+        'Listener' { 'lightblue' }
+        'Context' { 'lightgreen' }
+        'Response' { 'orange' }
+        default { 'darkyellow' }
+    }
+    "${Who}::${What} ${Message}" | Write-Host -bg $Color -fg black
+}
+
+'tip: Open a new window and run
+
+    > irm http://localhost:9092
+' | write-host -fore red
+
+if( $listen.IsListening ) {
+    throw 'nope'
+    # or
+    $Listen.Dispose()
+    $Listen = $Null
+}
+
+[Net.HttpListener]$Listen = @{}
+$listen.Prefixes.add('http://localhost:9098/')
+$Listen.Start()
+
+Log Task Start 'Async Wait'
+$task = $Listen.GetContextAsync()
+try {
+    while ( -not $Task.AsyncWaitHandle.WaitOne(200)) {
+        Log Task Sleep 'tick 200ms'
+    }
+    $ctx = $task.GetAwaiter().GetResult()
+    $ctx.Response.StatusCode = 200
+    $ctx.Response.ContentType = 'text/html'
+
+    $message = 'hi world 🐒 !'
+    $byte_str = [Text.Encoding]::UTF8.GetBytes( $message )
+    $json = ($ctx.Response | ConvertTo-Json -wa 0 -Depth 0 -Compress)
+    Log Response Write $json
+    $ctx.Response.OutputStream.Write( $byte_str, 0, $byte_str.Length )
+
+} finally {
+    Log Response Close
+    Log Listen Close
+    $ctx.Response.Dispose()
+    $listen.Dispose()
+}

Pwsh/Web/readme.md

@@ -1,5 +1,6 @@
 ## Web related scripts
 
 - [Net.HttpListener Basics.ps1](Net.HttpListener%20Basics.ps1)
+- [Net.HttpListener AsyncWait And Safe Cancelation](./Net.HttpListener%20Part2%20Async%20Cancel.ps1)
 
 ![screenshot](./img/Net.HttpListener-Basics.png)