sdk/samples/all in on code/Visual Studio 2010/VBASPNETReverseAJAX/Client.vb

   1 '****************************** Module Header ******************************\
   2 ' Module Name:    Client.vb
   3 ' Project:        VBASPNETReverseAJAX
   4 ' Copyright (c) Microsoft Corporation
   5 '
   6 ' Client class is used to synchronize the message sending and the message receiving.
   7 ' When DequeueMessage method is called, the method will wait until a new message
   8 ' is inserted by calling EnqueueMessage method. This class benefits ManualResetEvent
   9 ' class to achieve the synchronism.
  10 '
  11 ' This source is subject to the Microsoft Public License.
  12 ' See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.
  13 ' All other rights reserved.
  14 '
  15 '*****************************************************************************/
  16
  17 Imports System.Collections.Generic
  18 Imports System.Threading
  19
  20 ''' <summary>
  21 ''' This class represents a web client which can receive messages.
  22 ''' </summary>
  23 Public Class Client
  24     Private messageEvent As New ManualResetEvent(False)
  25     Private messageQueue As New Queue(Of Message)()
  26
  27     ''' <summary>
  28     ''' This method is called by a sender to send a message to this client.
  29     ''' </summary>
  30     ''' <param name="message">the new message</param>
  31     Public Sub EnqueueMessage(ByVal message As Message)
  32         SyncLock messageQueue
  33             messageQueue.Enqueue(message)
  34
  35             ' Set a new message event.
  36             messageEvent.[Set]()
  37         End SyncLock
  38     End Sub
  39
  40     ''' <summary>
  41     ''' This method is called by the client to receive messages from the message queue.
  42     ''' If no message, it will wait until a new message is inserted.
  43     ''' </summary>
  44     ''' <returns>the unread message</returns>
  45     Public Function DequeueMessage() As Message
  46         ' Wait until a new message.
  47         messageEvent.WaitOne()
  48
  49         SyncLock messageQueue
  50             If messageQueue.Count = 1 Then
  51                 messageEvent.Reset()
  52             End If
  53             Return messageQueue.Dequeue()
  54         End SyncLock
  55     End Function
  56 End Class