Is it necessary to close the connection of a tcplistener or tcpclient after every message received, or is it possible to close it at a later time while it continues to receive data? Is there any major security issue with leaving it open and listening? I know trojans tend to open a listener and leave it open, will my program be detected as such? Its just a simple chat program....
View 1 RepliesI have a background thread that sits waiting for new clients to connect to my TcpListener and when a new client connects it passes it off onto another worker thread and then loops straight back to waiting for another client. Like so:
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Obviously I could just handle the exception and ignore it but I'm sure there must be a more proper way of doing it. One thing I am thinking of trying is using the BeginAcceptTcpClient and EndAcceptTcpClient methods but for one thing I'm not sure if that will actually help and for another thing the Begin and End versions of methods have always confused me in the past... I mean for a start how do you know when to call End?
I figured this must be a fairly common problem but searching the forum only turned up one result and it wasnt any use. I'll keep playing around and trawling google but just wondered if anyone had come across this before?
How can I detect when a client disconnects from the TcpListener ?
Each of my clients is handled in a separate thread.
When it comes to database connections what is the difference between closing a connection & disposing a connection? I'm hoping to gain a more technical understanding of what happens when each is called & the effect on the database.
View 5 RepliesIm using the code from [URL] as a starter, most of the code is the same. the chat system works fine but on the client a added a disconnect button "clientSocket.Close()" and as soon as i click that i get errors, on the client, this is the code...
Private Sub getMessage()
For infiniteCounter = 1 To 2
[CODE]...
And this line...
serverStream.Read(inStream, 0, buffSize)
gives me "Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall."
Now im talking the server, after the client clicks disconnect or closes by task manager, looses connection, etc the server crashes and gives me.
I have a tcp server that uses TCPListener and the async method BeginAcceptTCPClient:
Imports System.Net.Sockets
Imports System.Threading
Imports System.Net
Public Class TCPServer
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My problem is that infrequently, I get an exception in the HandleAsyncConnection method:"An existing connection was forcibly closed by the remote host" right at the EndAcceptTCPClient method. At this point, the TCPListener seems to stop listening. The problem is that I can't test this easily, as it only happens on a remote test VM and only once every 24 hours or so. If I knew how to recreate the error with a test client, I would be able to figure this out. Wireshark shows a reset [RST] packet being sent at around the time of the exception. So I either need to know how to handle the exception, or how to recreate the problem with a test client.
I have many Listviews in my Form and Im retrieving stored procedures to populates my Listviews. Is it necassary to close the connection to SQL Server once I have finished populating my Listviews?The angle which im coming from is that every 30 seconds or so I need to re-populate my Listviews with the latest cut of data from SQL Server therefor Im probably going to slow down my application if it has to connect to SQL Server every 30 seconds to get the latest cut of data... instead of keeping the connection to the SQL Server Stored Procedure live so that I can use some sort of method to refresh the data?
View 2 RepliesI'm connecting to an ftp server in my .net application. After I send the file and try to close the connection, I'm getting an error. I'm trying to send the Quit command to the FTP server but getting no reply. I'm not sure what I'm doing wrong. I call this method: [code] Do you think something is wrong with the code of could it be a problem with the ftp server?
View 2 RepliesI'm writing a Windows form application in VS 2008. In the application I need to move among several SQL express databases (.mdf). I'm using the following commands to change the connection:
Me.MyTableAdapter.Connection.Close()
Me. MyTableAdapter.Connection.ConnectionString = "NewString"
Me. MyTableAdapter.Connection.Open()
I can see the form is showing data from the 2nd database. However, When I tried copying the 1st database (for a Save as function I'd like to implement), I got a system error saying "Cannot copy MdfFile: It is being used by another person or program.". Actually, I found all the visited databases were "being used" untill I closed my application. How do I break the connection completely?
I get this error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '*' at line 1 [Code]
View 14 RepliesI've got a fairly large VB.NET (3.5) project that makes a lot of database calls. So I created a namespace/class just to handle those fuctions. The idea was that this single point of entry into the database would give more control over validating input from users.
So my class looks something like this. (I've chopped some code out for readability, it works just fine except for all the open connections.
[Code]...
So I can close the data reader, but how do I reach back to that original database class and close the connection. If I close it in that original class it will bomb when I try to loop through the data reader the in calling class.I'm sure this is probably pretty obvious but I'm fried from the keyboard.
When connecting to a Sybase ASE database via ODBC using the code below, I'll occasionally get a '[IM006] [Microsoft][ODBC Driver Manager] Driver's SQLSetConnectAttr failed' error. this be caused by my code? I read here that I should be using the 'With' statement instead, but I don't understand how that would affect this.
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Finally starting some coding in VB.Net, I notice over the years, that we can say (in VB6)
Code: Dim MyForm_Stock as NEW frmStock
in the same session, being able to open, say 3 Stock Forms at the same time and maintain details independently of each of the other forms. Also am I able to maintain separate Database connections and the same table being opened and updated independently of each other by each separate form. What is actually taking place in terms of memory being used by each process? My ultimate goal is to be able to have ONE Module with all the possible data Connection and Recordset Opening and closing options, which I have failed miserably to do in my VB6 experience. Data access is an obvious module based set of subroutines. Others could be Date routines eg, Week Number of the year, Days Diff, Days to, etc. [Code]
I created some apps with the system.io and .net namespace. Sending an email and save files and such. Now I want to use pop3 to receive and read the messages on that account. I used TELNET to connect to my pop3 account and that is going well.
Here is the code I used in vb.
Dim client As New TcpClient
client.Connect("Pop3.whatever.com", 110)
If client.Connected = True Then
[code].....
How can I verify if the connection is ok and I'm logged in with this name and password? In Telnet I receive +ok after a command and input is correct, otherwise it generate -err.
My TCP Client connection dropped with no error. and it seem like receive 'empty data' after every 2nd message response to server.
Below is my function which having issue
Private Sub DoStreamReceive(ByVal ar As IAsyncResult)
Dim intCount As Integer
Try
[code]....
Is there a simple reason why it takes a long time to connect to a server? Take mIRC and xChat for example. Seems to instantly connect.
View 6 RepliesI've been Searching the Net for hours now, and i can't really seem to find anything clear and straight to the point.
I need to create a Server/Client application using VB.net 2008, it's actually my first time to have a database on another computer. So I first searched the internet for the things i need to make this software.
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I want to create a client-server application, it means I just need 1 database on the server.I have a computer and a laptop. I set my laptop's IP to 192.168.1.1 and my computer's IP to 192.168.1.2.Now I place the database on my computer, the database name is db_transportasi.Problem is, how to connect my computer's database from my laptopSpecification :I'm using this string below for my connection :Data Source=ARVID-THEODORUSSQLEXPRESS;Initial Catalog=DB_TRANSPORTASI;Integrated Security=TrueI already setup my SQL Configuration Manager, enabled the TCP/IP, switch to the IP Addresses tab and set the IPAII Port Properties to 2301I turned off my firewall so I don't have to set any exceptionQuestion
View 4 RepliesAm developing a server - client application using the system.net class , that will have more than 5000 simultenous client connection.what is the best way to manage multiple client connection like this?
View 3 RepliesI am a newbie in VB.NET I am using Sql Server Express 2005 as my database.I am currently working with my THESIS. A Human Reources Information System that concerns only with the file and record management of the employees. With two modules.a. Administrator for HR Manager (w/ installed vb.net and sqlserver express 2005)b. Staff for HR Clerk(w/ intalled vb.net)
Here is my problems:
1. I want to learn how to connect my vb.net application in each other using TCP/IP or any network connection tips.Scenario: If the client Save/Edit/Delete/ a record automatically it will saves on the admin sql database.
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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
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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?
For almost a week I am reading and trying to find a solution for checking connection state using a TCP Client (using socket class) In my scenario I have a TCP Client that is connected to a server (it is not controlled by me) and i want that from time to time to check the connection state, and reconnect if necessary.I have read a lot of information on the internet but i did not find a suitable solution.Briefly, these are the methods that i have found on the internet and try to implement.But unfortunatelly, i have found some scenarios where the TCP Server is closed and the TCP Client is still saying Connected 1.Example from MSDN
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I want to make an application that can push ads (website) to client..
Here is the case : Client try to connect to internet via wifi. Once the client is connected, server send a website address to client, and a popup (website sent by server) will appear in the client's computer in default browser.
I can list all IP connected to server, but i don't know how to push the website to client
Here is the code to list all IP connected to server : (import System.Net library)
String strHostName = "";
if(args == null || args.Length == 0){
strHostName = Dns.GetHostName();
[Code]....
and advise how I can change this connection string at run time. This is going to be on Client's computer and my application will need to change the name of computer after user enters it.
View 1 RepliesI want both the client and server to write and read resp. at a constant rate (which can be configured on the GUI of the client) to the buffer.I am able to send from the client at 150 bytes per packet Now, I should be able to read also at 150 bytes per packet on the server too Since, both are connected through a socket, can we retrieve the socket params (set on the client size, like 150 here) from the server end, using the tcpServer object.Or is it must to send an initial setup packet which tells about these client params and so accordingly the server can continue?
View 1 RepliesSo I'm making a Program to Start/Restart/Stop and running commands from the Console for my Server.Now when someone uses the console, I want to be alerted of it on my Mail.I am using Visual Studio 2010.
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I'm building application that will heavily use database (about 25k query's in few hours) , what is the best way to go:
A) use datareader and open new connection to the database on every client query.
B) load all the needed tables into dataset once the program loaded and use that dataset for the query's?
I have set the connection string of my dataset(typed) asData Source=MyHomeServerSQLEXPRESS;Initial Catalog=dbTestSharing;Integrated Security=TrueThis is going to be a client side application. I need to change the machinename in the connection string so it could connect with server.
View 1 Repliesi need to know about how to build connection with server and client? eg: my server is 140.134.5.1 and my client need to connect to it to do communication,how should i do?
View 6 RepliesI'm using a "wsHttpBinding" with a reliable session. I'd like to keep the client-server connection endless open. Therefore I need to set the ReceiveTimeout to "infinite". Has the "ReceiveTimeout" an other purpose (e.g. client crash detection; detecting a hanging request; etc) or can I set it to "infinite" without problems?
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