Properly Handle Disrupted TCP Connection?
Dec 19, 2010
I'm using TCP socket connetion between a server program and a client program. Multiple client programs shall connect to the same port. The problem is that if I close a client program I get the following error on the server-program:
System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)[code]......
View 1 Replies
ADVERTISEMENT
Apr 9, 2009
The app Im working on is dunning on an embedded xp machine. It recieves input from the serial port from an industrial process, and then a backgroundworker class calculates and updates the single form GUI with the results from the process. Very simple.Now, the customer want to allow automatic download of log files by an USB memory. The process should work like this:
1)User plug in an usb memory
2)SHow a virtual keypad (touch screen) where the user enter a security code
3)If code ok, show a 3 choice screen, if not ok show error message and allow the user to try again.
4) If user choose the "export all" button, this choose form will close and i display another form with a progress bar that show how all files are copied to the usb memory. When this process is complete, I will display teh form that says "remove the usb memory and press ok to restart the application.
As you see here lots of forms are created and disposed based on user choices. My biggest issue here is that I have no clear design pattern to work from.For example.. should I have this "chain" in the main gui form, or should I let each form create the next form. For example on the "select action" form, when I press export, should this form create and show the "copy progress" form, or should all forms be created and destroyed from the main gui form?
Also, such an issue like with the password. I put it as a constant on the main form, to avoid "magic numbers" in the code. And then I ran into problem because the "keypad" form is created on another thread and I can't access the costant on the main form, so I got a cross thread exception.Everything starts when an USB memory is connected. And the OnConnected eventhandler is running on a different thread than the main UI thread. how to design this chain of window creation/deletion is greatly appreciated. I show all forms with the SHowDialog because I dont want the user to be able to close the form unless he/she presses a button. And not by accident press somewhere else.
View 2 Replies
Aug 13, 2011
I need to find a Windows forms Text edit which can handle MS Word documents correctly.That is documents with Images, textboxes etc (.doc, .docx).I have tried Devexpress Xtrarichedit and TXText Control but when you load a MS Word Document (.doc, .docx) the document does not appear as it does in MS Word.That is Textboxes overlapping images are misaligned or have no transparent background option, so the white background of the textbox hides part ot the image.Has anybody had experience with 3rd party Document .net editors which mamage MS Word Documents correctly?
View 3 Replies
Mar 16, 2012
Im getting "connection property has not been properly initialized" error message on command2.ExecuteNonQuery().
I Have an SQL query which displays its result in a grid view (one result only) I'm attempting to get this result to update the database with this particular result from the SQL query
[Code]...
View 1 Replies
Apr 4, 2012
How do you actually handle connection Timeout to the database.Given a scenario where you are processing data half way through and the database crashed . So your connection between the database and your application would be broken. Most likely throw an exception error if u handle exceptions.What are your suggestions or your preferred way of handling such scenarios.
[Code]...
View 7 Replies
Jan 12, 2010
I'm trying to connect a remote mysql database. I'm doing it from a vb.net 2005 application with a connector mysql.data.dll What's happening is, suppose if I try to connect thrice it connects twice and once throwing an exception that says A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. there's nothing wrong with the code, otherwise it would never have connected
View 4 Replies
Apr 1, 2009
I am building a chat client/server. And I can connect and chat just fine, but when a user disconnects, the server does not recognize this and acts weird, often spamming the last message that was sent by the user..Also, it's like the client does not disconnect from the server even when I close the client app. Once I exit the program, VB acts like it is still debugging. Once the server is shut down however, I get this error:
IOException was unhandled:Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
serverStream.Read(inStream, 0, buffSize)I don't know how to make my client and server accept the fact that a client has disconnected...
View 16 Replies
Jun 22, 2010
I am looking for a code snippet which opens a image, creates a clone of this bitmap in memory disposes this opened image so that all handles are closed.
Usually we can open a bitmap using this[code...]
the following code however keeps the Image File locked until the application is running, any suggestions how to dispose it properly. (So that no handle is left open )
Things i already tried: use dispose method of bitmap <= doesnt work (need to write implementation)
Using Block also doesnt work.
View 2 Replies
Aug 5, 2011
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
[Code]...
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.
View 1 Replies
Mar 23, 2009
I wrote an application to handle a joystick with directinput. It works fine if it uses the handle of the main window but it doesnt happen the same if the handle is the one of the component that contains the joystick's operation.
I mean:
main form handle: 15
component handle (which is inside the window and the joystick needs the focus of this component to work): 25
It always work if the handle i initilizate the device is the main form (15).How can i use only the handle of the component?
View 1 Replies
Aug 25, 2009
How do I assign a My.Settings.Item connection string to cmd.Connection connection string value?
Dim cmd As New SqlCommand()
cmd.Connection = My.Settings.Item("csStaffHoursWorked")
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "spSaveDeltekImport"
View 3 Replies
Feb 5, 2010
Is there a way to display the connection properties dialog for connection string browsing(for database) in run time?
As I want the user to be able to connect to various database using the GUI.
View 6 Replies
Aug 3, 2011
i have an application. which is executed after every 5 mins. i have an open connection but it gives me the following error:
ExecuteScalar requires an open and available Connection. The connection's current state is closed.
my code is something like this. I have shown where all i am using ExceuteScalar()
Sub Main()
Try
connection.open()
cmd.ExecuteScalar()
[code]....
View 2 Replies
Aug 19, 2010
After running the following sub (VS debugger), I try to detach the database in SSMS, but it shows the connection open still and won't let me detach. If I close program in debugger, the database shows no connections. I check the dataadapter's connection in the finally block and is shows closed. What gives
Private Function ClientMasterDBFiles(ByVal MasterClientDBConnection As String, ByVal DBName As String) As DataTable
[Code]...
View 1 Replies
Mar 15, 2009
I have a simple scraper. It works on some websites, but on some there is this Error:
Quote:
IOException was unhandled Unable to read data from the transport connection: The connection was closed
It is occuring at "Dim htmlresults As String = Urlcontents.ReadToEnd()".
'Create the HttpWebRequest object
Dim req As HttpWebRequest = WebRequest.Create(URL)
'Set the timeout to 1 second (or 1,000 milliseconds)
req.Timeout = 10000
[code]....
View 2 Replies
Jun 21, 2010
I am attempting to write a program that will disable the Local Area Connection while leaving the Wireless connection enabled. My company is using net-books in our stores to demo air-cards and we need to keep them off of the LAN. I'm new to VB and VB.net, and it's been a while since I did any type of programming. I've gathered some code that others have posted in forums and tutorials and I'm working through a tutorial book, but I finally believe that I am stuck.
[Code]...
View 4 Replies
Nov 30, 2008
i make a class and when i call on form then that error occurs "ExecuteNonQuery requires an open and available connection, the connection Current stat is close "
Class Code isImports System.Data.SqlClientImports System.DataImports System.StringPublic Class DatabaseKits Dim Cn As New SqlClient.SqlConnection Public Function BuildConnection() As Boolean Try Cn.ConnectionString = "Persist Security Info=False;Integrated Security=True;Trusted_Connection=Yes;database=BizAimsPro2008;server=Server-2k3s" BuildConnection =
[code]....
View 3 Replies
May 17, 2012
I am connecting to a data stream that pushes data continuously and when I tried to set up a network stream I just could not connect and kept getting the 'not found' error. I used the httpwebrequest with webrequest.keepalive = true and started to consume the data by reading into a buffer and then appending to a stringbuilder. Once the stringbuilder reaches max size I flush it to a text file. The problem is that I get disconnected from the data stream because I am not reading the data fast enough. I need to keep the connection open and read the data while ensuring data gets stored in text files. If I use method "CONNECT" it does not connect to the stream.
While (True)
webrequest = DirectCast(Net.WebRequest.Create(url), HttpWebRequest)
webrequest.Credentials = New System.Net.NetworkCredential(username, password)
webrequest.Method = "GET"
[code]....
should I increase the buffer size and if so what is the max? that would mean I can read more data at a time and keep up with incoming push. Disparate here.
ACtually also I noticed that it gets stuck on this line
numbytesread = responseStream.Read(bufferread, 0, BUFFER_SIZE)
and then eventually I get disconnected.
View 1 Replies
May 17, 2012
I am connecting to a data stream that pushes data continuously and when I tried to set up a network stream I just could not connect and kept getting the 'not found' error. I used the httpwebrequest with webrequest.keepalive = true and started to consume the data by reading into a buffer and then appending to a stringbuilder. Once the stringbuilder reaches max size I flush it to a text file. The problem is that I get disconnected from the data stream because I am not reading the data fast enough. I need to keep the connection open and read the data while ensuring data gets stored in text files.If I use method "CONNECT" it does not connect to the stream.[code]
View 1 Replies
Sep 3, 2011
I understand the possibilities for encrypting a connection string in .net v4. I have a win forms application that will be used by multiple people on different machines. I understand that I need to protect the connection string at time of the app being first run on the target machine. However I am concerned that for a period of time my connection string will be unencrypted. I am looking for advice in how to deploy my app with the connection string already encrypted or encrypted during installation. encrypting the connection string in a secure way?
View 1 Replies
Dec 19, 2011
Try If functionmode = "ADD" Then
[Code]...
View 1 Replies
Jul 5, 2011
I got this error..The connection was not closed. The connection's current state is open.
This is coding to add data in Ms access in vb...
Imports System.Data.OleDb Public Class Form1
[Code]...
View 5 Replies
May 20, 2010
I'm developing a device app in VB.net that will access a SQL Server database. I need to establish a connection when the app is launched, and keep the connection open until the app is closed. I've done the following:In the Master Module:
Public CNN
As SqlConnection
In the Main menu form load:
CNN =
New SqlConnection(sqlConnString)
CNN.Open()
Then when I want to read from the database:
Dim sqlDR
As SqlDataReader
SQL = "SELECT Name FROM Table"
[code]....
When I run the same code without the global CNN, but rather dim the connection inside the Select function, all works well.
View 6 Replies
Jan 19, 2011
I'm developing an app in vb.net (visual studio 2008). I have a Teradata back-end that will be supporting multiple users in a production environment. I need to use variables in the connection string as the user/pass will be changed every 3 months.
For the gist of the application:
In it's most basic form - I have a search form which works correctly - it pulls results into a listbox and the user then double clicks the list box which will then open a form that is bound via table adapter to the back-end table (Teradata). My connection string is fine everywhere in the application. My problem is using a modified connection string for the "fill" function of the table adapter once the form is opened.
I'm using the code below for the on-load event and keep getting an "invalid connection string" - again, the connection string works fine everywhere else in the app, and the variables etc... are working correctly.
Private Sub adaptertest_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim DBConnStr As String = "Provider=TDOLEDB;Data Source=TDDEV;Persist Security
[Code].....
View 5 Replies
Aug 26, 2009
I'm facing a problem after installation any software setup that has a database in access(mdb file) How to I transfer file path in our connection string.
View 3 Replies
Mar 11, 2010
I'm trying to insert a new records into database, one of those records is a "datetime"...when I type a wrong date, and try to insert those values into database, i get an error (about wrong typed date etc.)...ok, that's fine, things need to work that way. But here comes the problem, I correct the date, and then try to insert values again...here I get an error from the post title. And this doesn't work until I close that form and run it again...here's part of my code:
Dim cvLicence As New SQL
Try
cvLicence.upis("INSERT INTO blabla (itsnotimportant) VALUES ('something')")
MsgBox("everything's fine", MsgBoxStyle.Information)
[code]....
View 7 Replies
Jun 12, 2011
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
exitwithout()
[code].....
View 1 Replies
Sep 7, 2011
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 Replies
Mar 18, 2012
I am trying to connect DSN from my VB 2008 project. When i try using myoledb.connectionstring="DSN=myDNSname" I get the following error message An OLEDB provider was not specified in the connectionstring.
View 1 Replies
Nov 9, 2009
i want to ask what is the difference between oledb connection and odbc connection. I have a case, my office used ncomputing then i have to developed an application using sqlserver 2000 and vb.net 2005, i used oledb connection. When i try to implement it in ncomputing, why user must has admin access level and dbo level in sql server, it seems trouble when all users are admin. But there's a rumor that when using odbc connection, we dont need to give admin access level for users.es.
View 1 Replies
