Question Simple CHAT application..

[atikojuane]

Hi! Sorry if this is a stupid thread... but well... I'm a starter in Visual Basic 2005...
I'm tring to create a simple chat app, but my code doesn't work...

Here is the code...
Client:

Imports System
Imports System.IO
Imports System.Net
Imports System.TeXT
Imports System.Net.Sockets

Public Class Form1
    Public tcpclnt As New TcpClient
    Public stm As NetworkStream
'Button1 sends message
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim asen As New ASCIIEncoding
        Dim ba(100) As Byte
        Application.DoEvents()
        ba = asen.GetBytes(TextBox3.Text)
        Application.DoEvents()
        stm.Write(ba, 0, ba.Length)
        Dim bb(100) As Byte
        Dim k As Integer
        Application.DoEvents()
        If stm.DataAvailable = True Then
            k = stm.Read(bb, 0, bb.Length)
        End If
        Dim i As Integer
        For i = 0 To k - 1
            TextBox2.Text = TextBox2.Text & Chr(13) & Chr(bb(i))
        Next
    End Sub

'Button2 connects
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        TextBox2.Text = TextBox2.Text & "Conected" & Chr(13)
        tcpclnt.Connect(TextBox1.Text, 8001)
        stm = tcpclnt.GetStream
    End Sub
End Class

Server:

Imports System.Net.Sockets
Imports System.Text
Imports System.Net
Imports System

Public Class Form1
    Public s As Socket

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ipAd As IPAddress
        ipAd = IPAddress.Parse(TextBox1.Text) 'the ip of textbox1.text
        Dim msg As String
        msg = "0"
        Dim mylist As New TcpListener(ipAd, 8001)
        Application.DoEvents()
        While (msg <> "fin")
            Application.DoEvents()
            mylist.Start()
            If mylist.Pending = True Then
                s = mylist.AcceptSocket
                Dim b(100) As Byte
                Dim k As Integer
                k = s.Receive(b)
                Dim i As Integer
                For i = 0 To k - 1
                    TextBox2.Text = TextBox2.Text & Chr(b(i))
                Next
                TextBox2.Text = TextBox2.Text & ControlChars.CrLf

            End If
        End While
        s.Close()
        mylist.Stop()
    End Sub


'Button2 sends the message
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim asen As New ASCIIEncoding
        s.Send(asen.GetBytes(TextBox3.Text))
        TextBox3.Text = ""
    End Sub

End Class

The problems are:

1. Sorry for the excesive DoEvents, but the app sometimes frozes, I don't know why
2. The first message I send from the client, is received by the server, but the rest don't..
3. When the client receives a message from the server, it has a strange symbol between each character... for example.. if message = "hello" , the client receives "h¤e¤l¤l¤o¤" , each ¤ is a big rectangle...
4. In previous versions the client app, after sending a message,frozes until the server send to the client a new message...

Thanks for your help

 

[jmcilhinney]

One of your primary issues is undoubtedly that you are doing everything in the UI thread. If your app is doing lots of processing then you need to do it on a secondary thread to leave the UI thread free to refresh the UI. You need to either make synchronous calls on a secondary thread or else make asynchronous calls. In general, I'd suggest the latter. As an example, check out the following, which should give you some ideas:

Asynchronous TcpListener & TcpClient