Hallo Forum,
ich versuche seit einigen Tagen in VB mit System.Net.Sockets (TcpClient, TcpListener, Pending, NetworkStream, ...) eine kleine Anwendung zusammen zu Stoppeln, die es mir erlaubt eine Client/Server-Verbindung zu simulieren. Das heist, a) alls Server
auf Horchposition gehen und dann als Client eine Verbindung aufbauen und Text senden/empfangen. Das muß doch prinzipiell gehen.
Im folgenden Code-Beispiel bekomme ich (in der unterstrichenen Zeile) eine Fehlermeldung "Der Vorgang ist für nicht verbundene Sockets unzulässig." Versuche ich jedoch ein client.Connect davor, spricht er von "Sockets bereits verbunden". Jetzt
weiß ich nicht mehr weiter, ich hoffe ihr könnt mir helfen,
lg heinz
Imports System.Net
Imports System.Net.Sockets
Module Module1
Sub Main()
Try
' Set the TcpListener on port 13000.
Dim port As Int32 = 13000
'Dim server As New TcpListener(IPAddress.Any, port)
Dim server As New TcpListener(IPAddress.Parse("10.0.0.1"), port)
' Start listening for client requests.
server.Start()
' Use the Pending method to poll the underlying socket instance for client connection requests.
Dim s As Int16 = 0
While s = 0
If server.Pending() Then Exit While
' Hier wird der anrufende Client simuliert
Connect("10.0.0.1", "Text vom Client")
End While
' Buffer for reading data
Dim bytes(1024) As [Byte]
Dim data As [String] = Nothing
' Enter the listening loop.
While True
Console.Write("Waiting for a connection... ")
' Perform a blocking call to accept requests.
' You could also user server.AcceptSocket() here.
Dim client As TcpClient = server.AcceptTcpClient()
Console.WriteLine("Connected!")
data = Nothing
' Get a stream object for reading and writing
Dim stream As NetworkStream = client.GetStream()
Dim i As Int32
' Loop to receive all the data sent by the client.
i = stream.Read(bytes, 0, bytes.Length)
While (i <> 0)
' Translate data bytes to a ASCII string.
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i)
Console.WriteLine([String].Format("Received: {0}", data))
' Process the data sent by the client.
data = data.ToUpper()
Dim msg As [Byte]() = System.Text.Encoding.ASCII.GetBytes(data)
' Send back a response.
stream.Write(msg, 0, msg.Length)
Console.WriteLine([String].Format("Sent: {0}", data))
i = stream.Read(bytes, 0, bytes.Length)
End While
' Shutdown and end connection
client.Close()
End While
Catch e As SocketException
Console.WriteLine("SocketException: {0}", e)
End Try
Console.WriteLine(ControlChars.Cr + "Hit enter to continue...")
Console.Read()
End Sub
'------------------------------------------------------------------------
Private Sub Connect(ByVal server As [String], ByVal message As [String])
Try
' Create a TcpClient.
' Note, for this client to work you need to have a TcpServer
' connected to the same address as specified by the server, port
' combination.
Dim port As Int32 = 13000
Dim tclient As New TcpClient(server, port)
'client.Connect(server, port) 'doppelter Connect
' Translate the passed message into ASCII and store it as a Byte array.
Dim data As [Byte]() = System.Text.Encoding.ASCII.GetBytes(message)
' Get a client stream for reading and writing.
' Stream stream = client.GetStream();
Dim stream As NetworkStream = tclient.GetStream()
' Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length)
Console.WriteLine("Sent: {0}", message)
' Receive the TcpServer.response.
' Buffer to store the response bytes.
''data = New [Byte](256) {}
' String to store the response ASCII representation.
''Dim responseData As [String] = [String].Empty
' Read the first batch of the TcpServer response bytes.
''Dim bytes As Int32 = stream.Read(data, 0, data.Length)
''responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes)
''Console.WriteLine("Received: {0}", responseData)
' Close everything.
''stream.Close()
''client.Close()
Catch e As ArgumentNullException
Console.WriteLine("ArgumentNullException: {0}", e)
Catch e As SocketException
Console.WriteLine("SocketException: {0}", e)
End Try
''Console.WriteLine(ControlChars.Cr + " Press Enter to continue...")
''Console.Read()
End Sub 'Connect
'------------------------------------------------------------------------
Public Sub PendingTeil(ByVal ipNr As String, ByVal portNumber As Long)
Try
'Dim ipAddress As IPAddress = Dns.Resolve("localhost").AddressList(0) 'ursprünglicher Code
Dim ipAddress As IPAddress = Dns.GetHostEntry("localhost").AddressList(0)
Dim tcpListener As New TcpListener(ipAddress, portNumber)
tcpListener.Start()
' Use the Pending method to poll the underlying socket instance for client connection requests.
If Not tcpListener.Pending() Then
Console.WriteLine("Sorry, no connection requests have arrived")
Else
'Accept the pending client connection and return a TcpClient object initialized for communication.
Dim tcpClient As TcpClient = tcpListener.AcceptTcpClient()
' Using the RemoteEndPoint property.
Console.Write("I am listening for connections on ")
Console.WriteLine(ipAddress.Parse(CType(tcpListener.LocalEndpoint, IPEndPoint).Address.ToString()))
Console.Write("on port number ")
Console.Write(CType(tcpListener.LocalEndpoint, IPEndPoint).Port.ToString())
End If
Catch
End Try
End Sub
End Module
TcpClient Anwendung auf einem PC in VB simulieren
