TCP與UDP差異

程式設計工藝大師

TCP與UDP差異

傳輸控制協議（Transmission Control Protocol, TCP）是一種連接導向的、可靠的、基於位元組流的運輸層（Transport layer）通信協議


用戶數據報協議（User Datagram Protocol, UDP）是一個簡單的面向數據報的傳輸層協議 ，UDP只提供數據的不可靠傳遞，它一旦把應用程序發給網路層的數據發送出去，就不保留數據備份（所以UDP有時候也被認為是不可靠的數據報協議）

圖片來源　http://blog.yam.com/ibma92157/article/27530306

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Option Explicit

Private Sub cmdSend_Click()
  Winsock1.SendData txtSend.Text
End Sub

Private Sub Form_Load()
  Winsock1.LocalPort = 7777
  Winsock1.Listen  '監聽
End Sub

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
  Dim strData As String
  Winsock1.GetData strData, vbString
  txtReceived.Text = strData
  If strData = "close" Then
    Winsock1.Close
    cmdSend.Enabled = False
    Winsock1.Listen
  End If
End Sub

Private Sub Winsock1_ConnectionRequest(ByVal requestID As Long)
  MsgBox "有人敲門"
  Winsock1.Close
  Winsock1.Accept requestID  '改成接受
  cmdSend.Enabled = True
End Sub


當ＣＬＥＩＮＴ

Option Explicit

Private Sub cmdSend_Click()
  Winsock1.SendData txtSend.Text
End Sub

Private Sub Form_Load()
  Winsock1.LocalPort = 7777
  Winsock1.Listen  '監聽
End Sub

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
  Dim strData As String
  Winsock1.GetData strData, vbString
  txtReceived.Text = strData
  If strData = "close" Then
    Winsock1.Close
    cmdSend.Enabled = False
    Winsock1.Listen
  End If
End Sub

Private Sub Winsock1_ConnectionRequest(ByVal requestID As Long)
  MsgBox "有人敲門"
  Winsock1.Close
  Winsock1.Accept requestID  '改成接受
  cmdSend.Enabled = True
End Sub