developer/Samples/NET 4.6/Samples for Parallel/AsyncDownload/AsyncDownload_VisualBasic/Module1.vb

   1 '--------------------------------------------------------------------------
   2 '
   3 '  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 '
   5 '  File: Program.cs
   6 '
   7 '--------------------------------------------------------------------------
   8
   9 Imports System.Net
  10 Imports System.Collections.Generic
  11 Imports System.Threading.Tasks
  12
  13 Module Module1
  14
  15     Sub Main()
  16         ' NOTE: Synchronous .Wait() calls added only for demo purposes
  17
  18         ' Single async request
  19         Download("http://www.microsoft.com").ContinueWith(AddressOf CompletedDownloadData).Wait()
  20
  21         ' Single async request with timeout
  22         Download("http://www.microsoft.com").WithTimeout(New TimeSpan(0, 0, 0, 0, 1)).ContinueWith(AddressOf CompletedDownloadData).Wait()
  23
  24         ' Concurrent async requests
  25         Task.Factory.ContinueWhenAll(
  26         {
  27             Download("http://blogs.msdn.com/pfxteam"),
  28             Download("http://blogs.msdn.com/nativeconcurrency"),
  29             Download("http://exampleexampleexample.com"),
  30             Download("http://msdn.com/concurrency"),
  31             Download("http://bing.com")
  32         }, AddressOf ConcurrentTasksCompleted).Wait()
  33
  34         ' Serial async requests
  35         Task.Factory.TrackedSequence(
  36             Function() Download("http://blogs.msdn.com/pfxteam"),
  37             Function() Download("http://blogs.msdn.com/nativeconcurrency"),
  38             Function() Download("http://exampleexampleexample.com"),
  39             Function() Download("http://msdn.com/concurrency"),
  40             Function() Download("http://bing.com")
  41         ).ContinueWith(AddressOf SerialTasksCompleted).Wait()
  42
  43         ' Done
  44         Console.WriteLine()
  45         Console.WriteLine("Press <enter> to exit.")
  46         Console.ReadLine()
  47     End Sub
  48
  49     Function Download(ByVal url As String) As Task(Of Byte())
  50         Dim wc As New WebClient
  51         Return wc.DownloadDataTask(url)
  52     End Function
  53
  54     Sub CompletedDownloadData(ByVal task As Task(Of Byte()))
  55         If task.Status = TaskStatus.RanToCompletion Then
  56             Console.WriteLine("Request succeeded: {0}", task.Result.Length)
  57         ElseIf task.Status = TaskStatus.Faulted Then
  58             Console.WriteLine("Request failed: {0}", task.Exception.InnerException)
  59         ElseIf task.Status = TaskStatus.Canceled Then
  60             Console.WriteLine("Request was canceled")
  61         End If
  62     End Sub
  63
  64     Sub SerialTasksCompleted(ByVal tasks As Task(Of IList(Of Task)))
  65         Dim failures = tasks.Result.Where(Function(t) t.Exception IsNot Nothing).Count()
  66         Console.WriteLine("Serial result: {0} successes and {1} failures", tasks.Result.Count() - failures, failures)
  67     End Sub
  68
  69     Sub ConcurrentTasksCompleted(ByVal tasks As Task(Of Byte())())
  70         Dim failures = tasks.Where(Function(t) t.Exception IsNot Nothing).Count()
  71         Console.WriteLine("Concurrent result: {0} successes and {1} failures", tasks.Length - failures, failures)
  72     End Sub
  73 End Module