TCP Communication - Send Data From The Client A Second Time
Oct 29, 2009
I've been playing around with the TCP client/server sample code I found on [URL] but I can't seem to get it to function correctly. The problem I am having is that if I try to send data from the client a second time I get nothing back, not even an error that it couldn't send data. Every time I run the project it works the first time but that's it. When I was running the code line by line it seems to get to 'networkStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))' and then it jumps over the rest of the routine.
[Code]...
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Oct 13, 2010
I'm not sure what I have done wrong, I am trying to get my program to send data (UsernamesPasswords) from client to server, then the server says if it's right or wrong.
The error is on this line:
Dim networkStream As NetworkStream = TcpClient.GetStream()
Heres the Client:
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
If TextBox1.Text = "" Then
MsgBox("You must enter UN/PW!")
[Code] .....
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Oct 29, 2009
I've been playing around with the TCP client/server sample code I found on [URL] but I can't seem to get it to function correctly. The problem I am having is that if I try to send data from the client a second time I get nothing back, not even an error that it couldn't send data. Every time I run the project it works the first time but that's it. When I was running the code line by line it seems to get to 'networkStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))' and then it jumps over the rest of the routine.
[Code]....
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Jun 27, 2011
Hey guys, I am trying to send data from client to server (encrypted) and the string sent from the client is not the same as recieved from the server. I've been killing my brain for hours to get this to work but I cant manage. Im converting everything to Base64 string.
Client:
Public Sub SendMessage(ByVal msg As String)
Try
SyncLock myclient.GetStream
sw = New IO.StreamWriter(myclient.GetStream)
[code]....
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Aug 20, 2010
I have programmed a chat application in VB but as soon as I send any data from a client the server will send it to all. It should send a reply only to a particular client. This is the function I have used.
[Code]...
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Jan 13, 2011
Client/Server Application in vb.net 2010 i have created but it was just basic one. I need to show send data from client to sever and sever to client and and more functionality. (like showing price ot item or anything
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Mar 18, 2009
I have a large class that I built to act as a TCP server for one of my silverlight applications. When a user connects it stores the tcp client into a table for later communication. The problem is that when I send data, with more than one client connected, it loops through both open TCP Clients but some how sends the data twice to the same client.... the other tcp client never receives his data. This isn't a logic issue as I can step through the code and see that it is clearly taking each individual TCP client out of the table and sending it the data. They all use the same port... could that be the issue? And if so how do I make it so that it can connect on one port then transfer to another? I have tried using different computers for connecting but still the most recently connected client receives all of the packets of data.
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Sep 21, 2011
In our project we've decided to put an exam generator using vb.net and after generate you can send it to client computer/students. *server computer/teacher will the one who will use exam generator and send it to the client computer/student*student will recieve it and then send it back again to the server computer/teacher*teachers will going to generate an exam depends on the type of exam, so i think im going to make it a wizard type environment
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Jul 7, 2011
I made some code in vb.net which checks if a certain process is running, and returns a 1 if it is, or a 0 if it isn't. Now I want it to send a packet to my server or something which would log the IP of the client, or something similar.
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Jan 17, 2012
Im doing a little program (.net2) that need to get info from a server.For starters I just want the Client-program to send a "Hi" and receive a"Ok" from server when client-program is started.
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Feb 2, 2011
I am facing problem in asynchronous socket communication.
1)I wanted to perform connect(from client to server) operation on enter button and send the data whatever client want to send and disconnect from server. And again client should get connect to server whenever client wanted to send data. this is the mechanism.
i.e how to reuse the socket.
2)Again Server should able to send the data to client.
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Jul 23, 2008
The problem I have is: When I click on cmdListen in the server form and cmdConnect in the client form,both programs won't respond and they crash for some reason I don't know.
Client source code:
Code:
Imports System.Net.Sockets
Imports System.Text
Public Class Form1
[CODE]...
Code:
Imports System.Net.Sockets
Imports System.Text
Public Class Form1
[CODE]...
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May 12, 2011
I'm doing a small project. It works on a LAN. The working of the project is:In client side, a user would enters "username" and "password". It would sent that to the server, along with the time.The server would authenticates info on checking a db and writes some info to the db.Also, the server should be able to sent some commands or instructions to the clients.These commands on received by the client, it would invoke certain functions/subs on the client based on the command.So, would it be better to use TCP client & listener or WCF ?
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Aug 26, 2010
I have created a Client that can send and receive data via TCP sockets. The objects stored on the serverside are the *exact* same object used for the client. They use the same send and receive protocols.
Now, when i send a string from the server to the client , it does precisely what it should do. However when I send a string to the server.... I do receive the string as an equal length of NULL characters. I run the server and client locally.
Basicly what can influence the behaviour between two completely identical objects performing the exact same task? I wonder if there is some socketflag issue if the TCPlistener.accept function returns a completely different setup then the one I R used to.
(if it is of any interest, the send protocol is asynchronious)
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Aug 14, 2011
I have a client/server program. There is a variable called readData that takes returndata and places it there. My question is, why can't I access this variable directly, for instance, varC = readData and then try to access a piece of it i.e. textbox1.text = varC(2), I get an error "object reference not set to instance of an object". Why is this happening? It is because the readData is a networking 'component'? How do I get around this? I can post more code from the server app if needed.
[Code]...
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Oct 4, 2011
The client/server communication will only take place in the same network.I can use TCP, but then I have to configure separate IP ports for every server instance. I can however simply use named pipes so I don't have to think about port numbers and simply use the name of the server instance.There will not be very frequent and/or large data client/server communication. It's some sort of a ERP application that will only communicate once per 30 seconds on average.
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Jun 3, 2010
How would I make a Visual Basic application talk to a web server? Someone will press something on the site and I want the application to display the information that the web site passes along to it.
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Nov 5, 2011
I have a TCP connection code for client and server communication. It's not meant to be malware but it collects the clients computer information and then connects to the server.
It successfully "connects" but then immediately disconnects.Here is the code for the server:
Dim Listener As TcpListener
Dim Client As TcpClient
Dim ClientList As New List(Of ChatClient)
Dim sReader As StreamReader
[Code]...
I have port forwarding all done and it works if I run the client and server on my own machine. If I run the client on another machine though It gives me a message box saying that it connected with the clients remote IP and at the same time it tells me it disconnected. The client never sends the system information. What is the problem?
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Sep 19, 2010
I have to send a sequence of video frames over UDP as fast and real-time as possible and while I got the basics working, I am running into all sorts of difficulties. Some of my goals:Data will normally be sent over dial-up (hence UDP instead of TCP), but also needs to support fast Ethernet.It's OK to occasionally drop frames (hence UDP instead of TCP).Need low latency. The frame the remote receives should be one that was recently sent (no more than a few frames waiting in buffers).I need to be able to detect the effective bandwidth so that I can compress the frames more or less to keep frame rate up.I break up frame data into one or more datagrams of about 500 bytes and each has a sequence number and other info. The receiver reassembles the entire frame and detects if any datagrams are missing.If the receiver detects more than a certain percentage of dropped frames (e.g. 50% over the last 10 frames), I send a TCP message to the sender to slow down by 50%. Sender than slowly increases speed by 5% each subsequent frame.Using System.Net.Sockets.UdpClient to send and receive the data.I have a separate TCP channel used for control messages back to sender.My main difficulty right now is detecting the effective bandwidth and dealing with latency, especially over dial-up (max ~4,000 bytes/sec). For example, if I try to send 100,000 bytes/second using TcpClient.Send() they ALL seem to arrive (no dropped datagrams) but with large latency by the time last datagram arrives. I think the TcpClient.Send() function is blocking until the buffer is able to send which messes up my current algorithm.
Can anybody point me to any sources of information for how to:Detect actual bandwidth over UDP.A better algorithm for dynamically adjusting bandwidth to suit the available pipe.Send data smoothly at the desired bandwidth.A way to detect and keep latency down to a minimum.I have been spinning my wheels over the last week and every time I solve one problem it seems another rears up is head.
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Oct 15, 2011
Below is my code, but when i send the message thru client socket i receive Specified argument was out of the range of valid values. Parameter name: size
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim serverStream As NetworkStream = clientSocket.GetStream()
Dim outStream As Byte() = _
System.Text.Encoding.ASCII.GetBytes("0800822000000000000004000000000000000920092126012345001")
[CODE]...
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May 9, 2009
how to create a client/server... But I couldn't... I don't want anything fancy. Just want the client to send the server 4 numbers, depending on the user's choice; after that, the server would turn off the pc, restart it, etc. It all depends on the number received. Is there a rather "simple" way to do it? If it's not to much trouble you could use Atheist's example. (Btw I don't understand the code and, yes, I've checked on [URL])
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May 2, 2011
I am starting a new project in VB, a card game modelled to be similar to a real card game.
I have the majority of the program planned out and have even started coding parts of it; my problem comes with the networking.This is a real-time card game (not turn-based) and I want to be able to play with real people (family mostly, so over LAN is what I'm after).
I have tried searching for code samples but I everything I have found seems more complicated than I feel is required for the task, introducing a lot of new concepts and not explaining them.
What I'm after is a simple way to exchange the information in real-time, I don't care so much for efficiency (at the moment) just ease of use - though if I need to wade through a heap of documentation I will. A perfect answer would tell me what the names of some of the controls/methods that would be appropriate are, even if it just re-affirms a bit of the complexity, you do not have to detail anything if you don't want to I just feel a bit at loss as to what exactly it is I am looking for!
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Jul 4, 2009
I have got the server app an the Client app Both Working to what i can see But My issue is i was only asked 4 days ago if i could add a Private msg and Whisper Feature as well as admin controls I have Done what i could to it then realised i have no idea how to only send the data to the selected client.
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Jul 15, 2009
i have been working on a chat program Server side and client side i have most of the features i was asked to put in but then once i got most of the bugs out i noticed something the server admin could send whispers and alerts to single users but then when you try do do it on the client side it wont work so i looked through it all and found my issue the user list on the client is only a list of the names in server hash table so i was wondering how do i send the hashtable and all of its data E.G. user connection information to the client so that it can send commands to individual users like the server side can
vb
Public clients As New Hashtable()
' This subroutine checks to see if username already exists in the clients
' Hashtable. If it does, send a REFUSE message, otherwise confirm with a JOIN.
[code]....
i tried to send the hashtable over the same method used to send the user names to the client but it cannot convert the hashtable to a string so that wont work so my question is How do i send the hash table to the user from the server then display the username on the client ??
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Sep 19, 2010
I need to control a device with a GPIB port. I have the commands that I need to use to do this; but I don't know which is the sintaxis in Visual Basic.
For example if I need to send a instruction like "START:0.01" to the external device which are the libraries that I have to include?, how should I write the programming line to do this?
The main tasks that I need to program are sending data, receiving data, and saving data
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Nov 9, 2009
[Code]....
Now as you can see it is sending the textbox1 text and then pressing enter then sending textbox2 text! Theres quite a few problems in that but before i discuss note: This code is in a Timer. Problem #1: It does not send the keys fully correct all the time because its trying to send them all at once! So i want it to send them 1 letter after the other with 200 ms sleep in them! Problem #2: The sleep is not working: The reason i know is because even after it did the first textbox1 text it didnt wait that 2000 ms!
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Nov 13, 2009
Alright im having some trouble with this peace of code
I use this to send my Account to the server but the server is just not reading it.[code]...
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Jan 3, 2012
I'm trying to send an email via the SMTP Client. The following line is rejected
CredentialCache.DefaultNetworkCredentials
The intellisense suggests this one:
Net.CredentialCache.DefaultNetworkCredentials
I'm using the System.Net.Mail Namespace...is this the correct one?
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Jun 2, 2010
I have a code here to send email, but its shows a error.
Error : The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required.
Code:
Dim smtpServer As New SmtpClient()
ProgressBar1.Value = 10
Dim mail As New MailMessage()
ProgressBar1.Value = 17
smtpServer.Credentials = New Net.NetworkCredential("myemailacc@gmail.com", "Password")
[Code] .....
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Mar 4, 2010
how to send mail via .net. However I do not seemlessly want to send the mail. I want a new mail message to open and I want to attach a file that i will export from crystal. So in short, It should use outlook on the client pc, open new mail, and add attachment. The user can then type custom message, and type email addresses.
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