TCP Transfer issues

[Rich]

I am writing two programs that are part of a Bulletin board system.
The program works right, but when information is downloaded, the server
program refuses to send more than 9 Kilobytes of data to the client.
How can this be fixed?

The code is:

Server (Running in a separate thread from UI):
H:
Const portNumber As Integer = 8000
Dim tcpListener As New TcpListener(por tNumber)
tcpListener.Sta rt()
Try
Dim tcpClient As TcpClient = tcpListener.Acc eptTcpClient()
Dim networkStream As NetworkStream = tcpClient.GetSt ream()
Dim bytes(tcpClient .ReceiveBufferS ize) As Byte
networkStream.R ead(bytes, 0,
CInt(tcpClient. ReceiveBufferSi ze))
Dim clientdata As String = Encoding.Unicod e.GetString(byt es)
Dim responseString As String = TextBox1.Text
Dim sendBytes As [Byte]() = Encoding.Unicod e.GetBytes(resp onseString)
networkStream.W rite(sendBytes, 0, sendBytes.Lengt h)
tcpClient.Close ()
tcpListener.Sto p()
Catch e As Exception
End Try
GoTo H
End Sub


Try
Dim tcpClient As New System.Net.Sock ets.TcpClient()
tcpClient.Conne ct(ip, port)
Dim networkStream As NetworkStream = tcpClient.GetSt ream()
If networkStream.C anWrite And networkStream.C anRead Then
Dim sendBytes As [Byte]() = Encoding.Unicod e.GetBytes(Text Box2.Text)
networkStream.W rite(sendBytes, 0, sendBytes.Lengt h)
Dim bytes(tcpClient .ReceiveBufferS ize) As Byte
networkStream.R ead(bytes, 0,
CInt(tcpClient. ReceiveBufferSi ze))
Dim returndata As String = Encoding.Unicod e.GetString(byt es)
Me.Close()
Else
If Not networkStream.C anRead Then
MsgBox("Data cannot be written.")
tcpClient.Close ()
Else
If Not networkStream.C anWrite Then
MsgBox("Data cannot be read.")
tcpClient.Close ()
End If
End If
End If
Catch ex As Exception
MsgBox("Error! Sever is not functioning!")
MsgBox(ex.ToStr ing)
MsgBox(ex.Messa ge)
End Try


Sorry about the sloppy coding. This is partially based on something i
found on Egghead cafe. If it matters, I am using a fast computer with
Windows XP Professional.

[Tom Shelton]

Re: TCP Transfer issues


Rich wrote:

I am writing two programs that are part of a Bulletin board system.
The program works right, but when information is downloaded, the server
program refuses to send more than 9 Kilobytes of data to the client.

Hmmm, right about the size of the normal network buffer size....

How can this be fixed?
>

Well, looking at the code, tells me that you are only doing a single
read. When you read data off a socket, it is not necessarily available
in a single read. That's why you need to either know exactly how many
bytes you are to receive, so you can read until you have that number of
bytes (which may involve multiple reads in a loop or buffering the data
if your going to use async sockets) or you need to have a end-of-stream
marker of some kind (CR/LF is a common choice for string data).

HTH,
Tom Shelton

[Rich]

Re: TCP Transfer issues

I figured out an easy way to fix it, when I looked at the line:
networkStream.R ead(bytes, 0, CInt(tcpClient. ReceiveBufferSi ze))

The intellisence says :
tcpClient.Recei ve Buffer Size as Integer
Gets or sets the size of the receive buffer.

Changing this number to a greater value (I changed it to 65,536 for
now) resolves the issue. The CInt says how much data to read. I have
not needed to change any settings in the server. I will experiment to
find out if a greater CInt makes it slow (like 100 MB download).

-Rich

[Tom Shelton]

Re: TCP Transfer issues


Rich wrote:

I figured out an easy way to fix it, when I looked at the line:
networkStream.R ead(bytes, 0, CInt(tcpClient. ReceiveBufferSi ze))
>
The intellisence says :
tcpClient.Recei ve Buffer Size as Integer
Gets or sets the size of the receive buffer.
>
Changing this number to a greater value (I changed it to 65,536 for
now) resolves the issue. The CInt says how much data to read. I have
not needed to change any settings in the server. I will experiment to
find out if a greater CInt makes it slow (like 100 MB download).
>
-Rich

Rich,

Changing the buffer size may solve your problem for the moment, but it
is not really a good long term solution... The standard way of doing
this is to, as I said to do multiple reads until you get the right
amount of data. If you look at most protocols, there are indicators
that tell you how much data to expect or an end-of-transmission marker.

--
Tom Shelton