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Feb 23rd, 2008, 07:43 PM
#1
Thread Starter
New Member
VB.Net TCP Client/Server
Hello,
I am very new to vb.net and I would like to know/learn how to make a basic client/server with whatever vb.net uses. I recently decided to convert from vb6 and I was using Winsock before, and now have decided to convert over to vb.net as vb6 wont be supported in the future, and a lot of the applications in vb6 don't work very well with Vista.
All I am looking for is a simple server that will listen for the incoming connection from the client, and then a client where all you do is push 1 button and it will send a test packet back to the server. I just need a very basic setup with no extra code just to see how it works.
Could someone please help me?
Thank you very much,
-3xpl0it
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Feb 23rd, 2008, 07:46 PM
#2
Re: VB.Net TCP Client/Server
Basically the two classes you need to look at are System.Net.Sockets.TcpClient and System.Net.Sockets.TcpClient.
Follow the link in my signature for an example on a pretty basic server/client solution.
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Feb 23rd, 2008, 08:24 PM
#3
Thread Starter
New Member
Re: VB.Net TCP Client/Server
Hello,
I looked around at that, but is there something even more basic? I just want the bare minimum amount of code to get this to work, so I know what I need and can build on just that base code. This will be my first major network project in vb.net, and I am very used to winsock like I said, so I am very lost... Could you help me with this/explain what each piece is for so I know what it is actually doing?
Thanks in advance!
-3xpl0it
Last edited by 3xpl0it; Feb 23rd, 2008 at 08:29 PM.
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Feb 26th, 2008, 05:28 AM
#4
Lively Member
Re: VB.Net TCP Client/Server
Well network programming isnt easy.
However its much better(for yourself too) to use the socket classes and understand how it works this way you can find/track/solve bugs much easier.
http://www.vwsoftwaresolutions.nl/winsock2005.dll.zip
That is the winsock.net component wich is basicly just a wraper around the system.net.sockets.socket class.
Its perfect for small projects but if you have a 'major' project and if i were you i should create my own code for your projects purpose only.
Greets
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Jun 12th, 2009, 09:56 AM
#5
New Member
Re: VB.Net TCP Client/Server
I'm not understanding the whole mutlithreading and use of Invoke()... How would I use Me.Close() within messageReceived() on the client side?
Great share by the way, I literally just started looking into VB.NET yesterday and I've learned a lot by playing with your code Atheist.
Thanks
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Jun 12th, 2009, 10:39 AM
#6
Re: VB.Net TCP Client/Server
Hey Phaaze and welcome to VBForums.
Since the messageReceived method will be executed on the worker thread that handles the incoming messages, you can not directly call a method on the form (such as Me.Close) from it, since you need to access forms and controls on the same thread as the one on which they where created.
This is why we use the Invoke method, which will execute the given method on the same thread that created the control we call it on. So in your case this would be the way:
Code:
Private Sub CloseForm()
If Me.InvokeRequired Then
Me.Invoke(New MethodInvoker(AddressOf CloseForm))
Else
Me.Close()
End If
End Sub
You can call this method from anywhere. If the currently executing thread is the "correct" one (that is, it is the thread that created the form that 'Me' refers to), the InvokeRequired property will return false and Me.Close will be invoked. If however InvokeRequired returns true, there will be a call to Me.Invoke, which will call the CloseForm method again, but this time, InvokeRequired will return false, and Me.Close will be invoked.
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Jun 12th, 2009, 11:10 AM
#7
New Member
Re: VB.Net TCP Client/Server
Thank you Atheist, I had just figured out the code I needed prior to reading your post but the explanation has helped greatly.
Furthermore, how are you supposed to handle client disconnections? I know I can send some sort of keepalive message to the server but I'm talking about when the client is closed, the server just crashes. How can I prevent the server from crashing?
Edit: I figured out I can use
Code:
If mClient.GetStream.DataAvailable Then
prior to
Code:
bytesRead = mClient.GetStream.Read(readBuffer, 0, BYTES_TO_READ)
and it prevents the server from crashing.
Thanks again for sharing this with us Atheist! This is a great example to learn from.
Edit 2: How can I get the clients IP Address? Also, how can I call a function in the Form1 class from the ConnectedClient class on the server?
Last edited by Phaaze; Jun 12th, 2009 at 01:18 PM.
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Sep 21st, 2009, 06:20 AM
#8
New Member
Re: VB.Net TCP Client/Server
EDIT: oops... wrong thread sorry
Last edited by fredfish; Sep 21st, 2009 at 06:30 AM.
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Feb 3rd, 2012, 01:48 PM
#9
New Member
Re: VB.Net TCP Client/Server
I am also new to vb. I am trying to write a program to monitor a port and write the data to an access table. I am not sure where to start; how I can test any code that I begin writing.
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Feb 7th, 2012, 12:23 AM
#10
Hyperactive Member
Re: VB.Net TCP Client/Server
MR. Lastly, welcome to the board.
please start a new thread of your own rather than taking someone elses.
Also, since you are new to VB let us know what other programing experience you have when you start your new thread. it will help us better vocalize an answer for you.
----------------------------------------------------
Missing the days of GWBasic 1.1
WaxyStudios.com
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Feb 29th, 2012, 08:56 PM
#11
New Member
Re: VB.Net TCP Client/Server
Originally Posted by ovanwijk
Well network programming isnt easy.
However its much better(for yourself too) to use the socket classes and understand how it works this way you can find/track/solve bugs much easier.
http://www.vwsoftwaresolutions.nl/winsock2005.dll.zip
That is the winsock.net component wich is basicly just a wraper around the system.net.sockets.socket class.
Its perfect for small projects but if you have a 'major' project and if i were you i should create my own code for your projects purpose only.
Greets
Can you provide some example programs for reference? I am new to client/server program in VB.net.
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Mar 1st, 2012, 09:26 AM
#12
Hyperactive Member
Re: VB.Net TCP Client/Server
Originally Posted by ovanwijk
Well network programming isnt easy.
However its much better(for yourself too) to use the socket classes and understand how it works this way you can find/track/solve bugs much easier.
http://www.vwsoftwaresolutions.nl/winsock2005.dll.zip
That is the winsock.net component wich is basicly just a wraper around the system.net.sockets.socket class.
Its perfect for small projects but if you have a 'major' project and if i were you i should create my own code for your projects purpose only.
Greets
Does it provide some way to allow UDP traffic inbound? that's been my greatest problem. not all routers are UPNP enabled. so far my biggest clue for how big business games get around router configurations has been UDP Hole Punching.
----------------------------------------------------
Missing the days of GWBasic 1.1
WaxyStudios.com
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Mar 3rd, 2012, 10:22 PM
#13
New Member
Re: VB.Net TCP Client/Server
hello.. may i...
i just new to vb..
how can i make an application such as LAN messengger that use client/server function?
where does i need to start?
can anyone guide me... i'm very lost..
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Aug 31st, 2012, 02:31 PM
#14
New Member
Re: VB.Net TCP Client/Server
Hello. I am trying to implement this for a simple server that would have multiple clients and will serve 5 weather parameters in one tab-delimited string. Connection and sending data is no problem, however, I am having problems with a memory leak and with disposing of disconnected clients. The removeClient subroutine does not really get rid of the client because I've noticed that doRead continues to execute even after the client disconnects. My CPU usage jumps to 100% when a client disconnects. In addition, the memory usage rises by about 8kB/s when it is running. I've tried setting up a Dispose call, but even after this call doRead continues to run. In my normal application I don't ever need to get rid of objects under execution is over. Any ideas?
Server Form
Code:
Imports System.Net.Sockets
Imports System.Threading
Public Class frmServerMain
Private VaisalaDevice As Vaisala
Private listener As System.Net.Sockets.TcpListener
Private listenThread As System.Threading.Thread
Private tmrWrite As Timer
Private TimerWriteDelegate As TimerCallback
Private Open As Boolean
Private clients As New List(Of ConnectedClient) 'This list will store all connected clients.
Private Sub frmServerMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
listener = New System.Net.Sockets.TcpListener(System.Net.IPAddress.Any, 43001) 'The TcpListener will listen for incoming connections at port 43001
listener.Start() 'Start listening.
listenThread = New System.Threading.Thread(AddressOf doListen) 'This thread will run the doListen method
listenThread.IsBackground = True 'Since we dont want this thread to keep on running after the application closes, we set isBackground to true.
listenThread.Start() 'Start executing doListen on the worker thread.
' Write to the port 4 times per second.
TimerWriteDelegate = AddressOf SendMessage
tmrWrite = New System.Threading.Timer(TimerWriteDelegate, Open, 0, 1000)
End Sub
Private Sub doListen()
Dim incomingClient As System.Net.Sockets.TcpClient
Do
incomingClient = listener.AcceptTcpClient 'Accept the incoming connection. This is a blocking method so execution will halt here until someone tries to connect.
Dim connClient As New ConnectedClient(incomingClient, Me) 'Create a new instance of ConnectedClient (check its constructor to see whats happening now).
AddHandler connClient.dataReceived, AddressOf Me.messageReceived
clients.Add(connClient) 'Adds the connected client to the list of connected clients.
Control.CheckForIllegalCrossThreadCalls = False
connClient.Username = incomingClient.Client.RemoteEndPoint.ToString
ListBox1.Items.Add(connClient.Username & " connected.")
Loop
End Sub
Public Sub SendMessage()
For Each cc As ConnectedClient In clients
cc.SendMessage("this is a test")
Next
End Sub
Public Sub removeClient(ByVal client As ConnectedClient)
If clients.Contains(client) Then
clients.Remove(client)
client.Dispose()
ListBox1.Items.Remove(client.Username & " connected.")
End If
End Sub
Private Sub messageReceived(ByVal sender As ConnectedClient, ByVal message As String)
'A message has been received from one of the clients.
'To determine who its from, use the sender object.
'sender.SendMessage can be used to reply to the sender.
Dim data() As String = message.Split("|"c) 'Split the message on each | and place in the string array.
Select Case data(0)
Case "CONNECT"
'We use GetClientByName to make sure no one else is using this username.
'It will return Nothing if the username is free.
'Since the client sent the message in this format: CONNECT|UserName, the username will be in the array on index 1.
If GetClientByName(data(1)) Is Nothing Then
'The username is not taken, we can safely assign it to the sender.
sender.Username = data(1)
End If
Case "DISCONNECT"
removeClient(sender)
End Select
End Sub
Private Function GetClientByName(ByVal name As String) As ConnectedClient
For Each cc As ConnectedClient In clients
If cc.Username = name Then
Return cc 'client found, return it.
End If
Next
'If we've reached this part of the method, there is no client by that name
Return Nothing
End Function
End Class
ConnectedClient Class
Code:
Public Class ConnectedClient
Implements IDisposable
Private mClient As System.Net.Sockets.TcpClient
Private mUsername As String
Private mParentForm As frmServerMain
Private readThread As System.Threading.Thread
Private Const MESSAGE_DELIMITER As Char = ControlChars.Cr
Protected disposed As Boolean = False
Public Event dataReceived(ByVal sender As ConnectedClient, ByVal message As String)
Sub New(ByVal client As System.Net.Sockets.TcpClient, ByVal parentForm As frmServerMain)
mParentForm = parentForm
mClient = client
readThread = New System.Threading.Thread(AddressOf doRead)
readThread.IsBackground = True
readThread.Start()
End Sub
Public Property Username() As String
Get
Return mUsername
End Get
Set(ByVal value As String)
mUsername = value
End Set
End Property
Private Sub doRead()
Const BYTES_TO_READ As Integer = 255
Dim readBuffer(BYTES_TO_READ) As Byte
Dim bytesRead As Integer
Dim sBuilder As New System.Text.StringBuilder
Do
Try
If mClient.Connected Then
bytesRead = mClient.GetStream.Read(readBuffer, 0, BYTES_TO_READ)
If (bytesRead > 0) Then
Dim message As String = System.Text.Encoding.UTF8.GetString(readBuffer, 0, bytesRead)
If (message.IndexOf(MESSAGE_DELIMITER) > -1) Then
Dim subMessages() As String = message.Split(MESSAGE_DELIMITER)
'The first element in the subMessages string array must be the last part of the current message.
'So we append it to the StringBuilder and raise the dataReceived event
sBuilder.Append(subMessages(0))
RaiseEvent dataReceived(Me, sBuilder.ToString)
sBuilder = New System.Text.StringBuilder
'If there are only 2 elements in the array, we know that the second one is an incomplete message,
'though if there are more then two then every element inbetween the first and the last are complete messages:
If subMessages.Length = 2 Then
sBuilder.Append(subMessages(1))
Else
For i As Integer = 1 To subMessages.GetUpperBound(0) - 1
RaiseEvent dataReceived(Me, subMessages(i))
Next
sBuilder.Append(subMessages(subMessages.GetUpperBound(0)))
End If
Else
'MESSAGE_DELIMITER was not found in the message, so we just append everything to the stringbuilder.
sBuilder.Append(message)
End If
End If
Else
mParentForm.removeClient(Me)
'Exit Do
End If
Catch ex As Exception
End Try
Loop
End Sub
Public Sub SendMessage(ByVal msg As String)
Dim sw As IO.StreamWriter
Try
SyncLock mClient.GetStream
sw = New IO.StreamWriter(mClient.GetStream) 'Create a new streamwriter that will be writing directly to the networkstream.
sw.Write(msg)
sw.Flush()
End SyncLock
Catch ex As Exception
MessageBox.Show(ex.ToString)
End Try
'As opposed to writing to a file, we DONT call close on the streamwriter, since we dont want to close the stream.
End Sub
Protected Overridable Overloads Sub Dispose( _
ByVal disposing As Boolean)
If Not Me.disposed Then
If disposing Then
'managedResource.Dispose()
End If
' Add code here to release the unmanaged resource.
'unmanagedResource = IntPtr.Zero
' Note that this is not thread safe.
End If
Me.disposed = True
End Sub
#Region " IDisposable Support "
' Do not change or add Overridable to these methods.
' Put cleanup code in Dispose(ByVal disposing As Boolean).
Public Overloads Sub Dispose() Implements IDisposable.Dispose
Dispose(True)
GC.SuppressFinalize(Me)
End Sub
Protected Overrides Sub Finalize()
Dispose(False)
MyBase.Finalize()
End Sub
#End Region
End Class
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Sep 5th, 2012, 09:09 PM
#15
New Member
Re: VB.Net TCP Client/Server
Error 1 Type 'Vaisala' is not defined. F:\Projects\AMRSyncTcp\Server\Server\frmServerMain.vb 4 30 Server
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Sep 6th, 2012, 07:35 AM
#16
New Member
Re: VB.Net TCP Client/Server
Originally Posted by dimasiano
Error 1 Type 'Vaisala' is not defined. F:\Projects\AMRSyncTcp\Server\Server\frmServerMain.vb 4 30 Server
Comment out any reference to Vaisala as it will not work unless you have that instrument.
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