Re: MDI Forms - Visual Basic Discussion Boards

How to detedt a socket client connection loss in TCP Listener? [modified]

keithyang8-Jan-07 15:59

8-Jan-07 15:59

Hello everybody, I wrote the following code snippet to establish a TCP Listener – Client connection. I use a state machine to loop this sub in a thread so that it can continuously receive data from the client.

But there are few problems that I don not know how to handle.

First, if a client is already connected to the TCP listener and the client closed this connection at the remote side, how can I detect this connection loss? For example, I use the HyperTerminal to create a WinSock connection to TCP listener and disconnect it in the HyperTerminal.

Second, how do I handle multiple connections simultaneously?

I do appreciate your help.

<br />
    Public Sub socketHandler()<br />
        Dim _HostSocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP)<br />
        Dim _TcpListener As New TcpListener(IPAddress.Parse(getLocalIP), Integer.Parse(TextPortListen.Text))<br />
<br />
        Try<br />
<br />
            While True<br />
<br />
                Select Case sockStatus<br />
<br />
                    Case socketStatus.SOCKET_IDLE<br />
                        'does not do anything but wait<br />
<br />
                    Case socketStatus.SOCKET_STOP<br />
                        _TcpListener.Start()<br />
                        sockStatus = socketStatus.SOCKET_LISTEN<br />
<br />
                    Case socketStatus.SOCKET_LISTEN<br />
<br />
                        If _TcpListener.Pending = True Then<br />
                            _HostSocket = _TcpListener.AcceptSocket<br />
                            sockStatus = socketStatus.SOCKET_CONNECTED<br />
                        End If<br />
<br />
                    Case socketStatus.SOCKET_CONNECTED<br />
<br />
                        If _HostSocket.Poll(1, SelectMode.SelectRead) Then<br />
                            ' _HostSocket has data to be read. <br />
                            ' Call the Socket Available method on _HostSocket; <br />
                            ' assign the return value (Bytes available) to an integer variable. <br />
                            Dim numBytes As Int32 = _HostSocket.Available<br />
                            ' Instantiate an array of Bytes which is the size of the <br />
                            ' number of Bytes available. <br />
                            Dim Data(numBytes) As Byte<br />
                            ' Call the Socket Receive method. <br />
                            ' Receives data from a connected Socket. <br />
                            _HostSocket.Receive(Data)<br />
                            ' Convert the Byte array received into a String <br />
                            SetText(Encoding.ASCII.GetString(Data), TextRxData)<br />
                        End If<br />
<br />
                    Case socketStatus.SOCKET_CLOSING<br />
<br />
                        If _HostSocket.Connected Then<br />
                            _HostSocket.Close()<br />
                        End If<br />
                        _TcpListener.Stop()<br />
                        sockStatus = socketStatus.SOCKET_CLOSED<br />
<br />
<br />
                    Case socketStatus.SOCKET_CLOSED<br />
                        'the current socket connection is closed. set to idle status<br />
                        sockStatus = socketStatus.SOCKET_IDLE<br />
                End Select<br />
<br />
            End While<br />
<br />
        Catch ex As Exception<br />
            MsgBox(ex.Message.ToString)<br />
        End Try<br />
<br />
    End Sub<br />

-- modified at 22:11 Monday 8th January, 2007

V.B 6

J.Paul Ghetty8-Jan-07 15:12

J.Paul Ghetty

8-Jan-07 15:12

I'm just learning VB, (a nug) I'm told that msdn can be very helpful.
is msdn a "redistributable"? I'm trying to find it, not having much luck as I'm not finding anything that is called Just "Msdn" Help? J.Paul Ghetty

Re: V.B 6

Christian Graus8-Jan-07 15:21

Christian Graus

8-Jan-07 15:21

You won't find any VB6 help in MSDN. VB6 has been obsolete for about 5 years and unsupported by MS for a fair while now. Why are you learning it ? If you want to learn to program for anything other than a laid back hobby, VB6 is a bad idea.

MSDN comes on CD with visual studio, unless you download a free version ( VB Express Edition is what I'd be recommending to you ). It's also a website - msdn.microsoft.com[^].

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Datagrid - Refresh

Larry White8-Jan-07 11:19

Larry White

8-Jan-07 11:19

Any help would be appreciated.

I am trying to design my form to display the data using a Selected Value from a listbox. I set the lbShop.SelectedIndexChanged event to refresh the datagrid when a new value is selected. The variable SShop1 is changed correctly as each item in the listbox is selected, but the datagrid will not refresh using the SQL Select string. What I need is the new SQL Select command to run with the user selected variable, clear the datagrid, and display the data from the new SQL string.

Private Sub frmAllOpenbyShop_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

cnn.Open()
reader = dr5.ExecuteReader()
While reader.Read()
values.Add(reader.Item("Shops").ToString())
End While
lbShop.DataSource = values
reader.Close()

Try
'Attempt to load the dataset.
Me.loadDoc()
Catch eLoad As System.Exception
'Add your error handling code here.
'Display error message, if any.
System.Windows.Forms.MessageBox.Show(eLoad.Message)
End Try
End Sub
*******************************************************************************
Public Sub dadapt1()
SShop1 = lbShop.SelectedItem
DAdapt.SelectCommand = New SqlCommand
DAdapt.SelectCommand.CommandType = CommandType.Text
DAdapt.SelectCommand.Connection = cnn1
DAdapt.SelectCommand.CommandText = "Select SystemName, Shop, ActionTaken, TaskNotes, Symptoms, TroubleShooting, Conclusion FROM Workorders WHERE TaskNotes LIKE '" & SShop1 & "' ORDER BY Shop"
End Sub
*******************************************************************************
Public Sub loadDoc()
Me.dadapt1()
Try
dsSearch2.Clear()
DAdapt.Fill(dsSearch2)
Catch ex As SqlException
End Try
grdWorkorders.DataSource = dsSearch2
End Sub
*******************************************************************************
Private Sub lbShop_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lbShop.SelectedIndexChanged
grdWorkorders.Refresh()
Me.loadDoc()
End Sub

LWhite

Re: Datagrid - Refresh

Christian Graus8-Jan-07 12:49

Christian Graus

8-Jan-07 12:49

If you want to do a LIKE query, you need to put the wildcards in, otherwise just use =.

This is not production quality code, a SQL injection attack will perform whatever SQL the malicious user wants to run on it.

Haev you stepped through to see how the code is being executed ?

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Re: Datagrid - Refresh

Larry White9-Jan-07 4:53

Larry White

9-Jan-07 4:53

Thank you, I replaced the LIKE with = as I didn't need a wildcard search anyway. I will have to look at tightening the code to protect from attack. I stepped through the code and find that if I leave the SShop1 variable = nothing, I get my entire database, as expected, but when I try to set the variable to = a selection from the listbox, I get nothing displayed, just an empty datagrid. This is the line I rem'd out to get a default variable of nothing: SShop1 = lbShop.SelectedItem

Thank you for responding to my question.

Larry

LWhite

MDI Forms

Jason Timothy Holland8-Jan-07 10:01

Jason Timothy Holland

8-Jan-07 10:01

I want to be able to move the minimized form. not change the location for when it restores. I want to minimize it with a left property of 190.

Jason Holland
Stockroom Manager
AE&C Services

Re: MDI Forms

Dave Kreskowiak8-Jan-07 10:09

Dave Kreskowiak

8-Jan-07 10:09

You don't have access to that. The MdiClient control controls the position of minimized (iconed) windows.

Why do you want to do this anyway?

Dave Kreskowiak
Microsoft MVP - Visual Basic

Encrypt File using User Supplied Password

hkinser98-Jan-07 9:57

hkinser9

8-Jan-07 9:57

Hello everyone.

I've read several articles on the internet in trying to figure this out; however, those article seem a bit over my head apparently and I can't seem to find a code example that is simple and to the point to implement.

I'm coding a password manager program in vb 2005. All that is left to do is obtain a password from the user the first time they start the program, and use that password as the encryption key in creating the file that will hold the data from the listview control.

For now, the login form is simply taking the password the user enters and encrypting it inside a separate file for now as you will see below - the file itself is not encrypted. I have all the forms complete and the listview data is writing to a currently unencrypted file for now. I just want to make it all one file with the user password being the key to encrypt it all.

Here is the login code I'm using if we can somehow modify it to do what I'm looking for:

If txtUserPsw.Text = txtPswVerify.Text And Me.txtPswVerify.Text.Length >= 8 Then
Try
' Obtain a FileStream object.
Dim aFileStream As New FileStream(AppPath(False) & "\passsafe.bin", FileMode.Create)
' Obtain a BinaryWriter object.
Dim aBinaryWriter As New BinaryWriter(aFileStream)
' Encrypt the new password and binary write to a binary file.
aBinaryWriter.Write(EncryptPassword.EncryptString(Me.txtPswVerify.Text))
' Close the FileStream and the BinaryWriter objects.
aFileStream.Close()
aBinaryWriter.Close()
' Message user.
MessageBox.Show("Password was encrypted and saved. Don't forget it!")
'Display Main form (Frmlogin)
Dim safe As New frmSafe
'Hides login form
Me.Visible = False
safe.ShowDialog()
'disposes login form on exit of main form
'Application.Exit()
Me.Close()
Catch ex As Exception
' Message user.
MessageBox.Show("Password was not saved. ERROR: " & ex.Message)
End Try
End If

Thanks everyone!

Sincerely,
Harold

Printing landscape pages not working

Knoen8-Jan-07 9:39

Knoen

8-Jan-07 9:39

Im trying to print a document in landscape. But it seems my program only print in regular orientation, that is the on ive set in the printer driver under Start->Settings->Printer and faxes.

Im using the QueryPageSettings sub when it prints and set e.PageSettings.Landscape = True but nothing happens.

Anyone got same problems or have any ideas?

Thanks

DataGridView.Columns.AddRange

kindman_nb8-Jan-07 9:10

kindman_nb

8-Jan-07 9:10

Hi ,
I'm using vb.net 2005 , the next code to view some fields on DataGridView Contrl ,

rivate Sub AddCol()

DataGridView.Columns.AddRange(New System.Windows.Forms.DataGridViewColumn() {Col1, Col, Col, Col})

Me.Col1.DataPropertyName = "Field1"
Me.Col1.HeaderText = "Col1"
Me.Col1.Name = "Col1"
Me.Col1.Width = 40

Me.Col2.DataPropertyName = "Field2"
Me.Col2.HeaderText = "Col2"
Me.Col2.Name = "Col2"
Me.Col2.Width = 40

Me.Col3.DataPropertyName = "Field3"
Me.Col3.HeaderText = "Col3"
Me.Col3.Name = "Col3"
Me.Col3.Width = 40

Me.Col4.DataPropertyName = "Field4"
Me.Col4.HeaderText = "Col4"
Me.Col4.Name = "Col4"
Me.Col4.Width = 40

End Sub

when i reuse the same sub again then I get a new order of cols ,,

it's a strange ! I user the same code

I will give Rose | [Rose]

for any one help me

jooooo

Re: DataGridView.Columns.AddRange

Dave Kreskowiak8-Jan-07 9:20

Dave Kreskowiak

8-Jan-07 9:20

Your code has some problems. Like if you're going to use this code again and again, I don't see anything to clear out the existing columns so you don't end up adding a new set of columns to the ones that are already there.

Next, what is Col in this line and why are you adding it 3 times?

DataGridView.Columns.AddRange(New System.Windows.Forms.DataGridViewColumn() {Col1, Col, Col, Col})

This code isn't making much sense. The Me's tell me that you have DataGridViewColumn objects sitting on the form???

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: DataGridView.Columns.AddRange

kindman_nb8-Jan-07 10:39

kindman_nb

8-Jan-07 10:39

Thanks Dave for your reply ..
Really I'm waiting you and you for reply ,, and I still rememper you every day and rememper your words ,, God bless you !

I'm sorry that I mean on this line
DataGridView.Columns.AddRange(New System.Windows.Forms.DataGridViewColumn() {Col1, Col2, Col3, Col4})

I want to understand what i mean , see , I'm using Master/Details form,
and I did an ides which when the user add or edit then I copy the details records to a temp table , then after that when save the program copy all recors from temp taple to Base table , is idea is good on many sides ,, I see that,
from that I change the DataSource and DataMember of DataGridView , then I found that the order and header text of columns is changed , then I try to solve that problem by that , on every action the program clear all columns an reAdd it with it's propertis that I need , then the Problem that I entioned it on first message faced me ,, I hope you see ,,
Rose | [Rose]

jooooo

Re: DataGridView.Columns.AddRange

Dave Kreskowiak9-Jan-07 2:53

Dave Kreskowiak

9-Jan-07 2:53

I suggest straightening out your column code and create then add each column as you make it. Oh! For future posts, copy and paste the actual code you're using. DO NOT RETYPE IT in the post yourself. You're more likely to cover up the problem with other mistakes if you do.

Private Sub AddCol()
    Dim newCol As New DataGridViewTextBoxColumn     ' NOT DataGridViewColumn!

    newCol.DataPropertyName = "Field1"
    newCol.HeaderText = "Col1"
    newCol.Width = 40
    DataGridView1.Columns.Add(newCol)

    newCol = New DataGridViewTextBoxColumn
    newCol.HeaderText = "Col2"
    newCol.Width = 40
    DataGridView1.Columns.Add(newCol)

    ....
End Sub

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: DataGridView.Columns.AddRange

kindman_nb9-Jan-07 7:25

kindman_nb

9-Jan-07 7:25

Really Thanks,,,,
Rose | [Rose]

jooooo

Shared Printer (send it a string)

oogyboogyme8-Jan-07 9:02

oogyboogyme

8-Jan-07 9:02

I'm having a problem printing (i'm really sending it a string in its own language) to a shared network printer.
I have written the following code:

Dim idFile As Integer = FileSystem.FreeFile

FileSystem.FileOpen(idFile, "\.0.0.1\ZebraLP2844", OpenMode.Append, OpenAccess.Write, OpenShare.Shared)

strTemp = "N" & vbCrLf 'Clear Buffer
strTemp = strTemp & "q816" & vbCrLf 'Label Width in dots (4 inches?)
strTemp = strTemp & "Q203,24+0" & vbCrLf 'Label Height and gap in dots (1 inch)
strTemp = strTemp & "S2" & vbCrLf 'S = Speed Select
strTemp = strTemp & "D10" & vbCrLf 'D = Density
strTemp = strTemp & "ZT" & vbCrLf 'Direction set to forward? (ZT is what u want)
strTemp = strTemp & "OD" & vbCrLf 'Direct Thermal Mode
strTemp = strTemp & "A25, 12, 0, 5, 4, 2, N, """ & myName & """" & vbCrLf
strTemp = strTemp & "LO50, 5, 800, 20" & vbCrLf
strTemp = strTemp & "A75, 12, 0, 5, 4, 2, N, """ & mySN & """" & vbCrLf
strTemp = strTemp & "P" & numCDPrint.Value().ToString & vbCrLf

FileSystem.Print(idFile, strTemp)
FileSystem.Reset()

But on line:
FileSystem.FileOpen(idFile, "\.0.0.1\ZebraLP2844", OpenMode.Append, OpenAccess.Write, OpenShare.Shared)

I Recieve this error message:
"FIleStream was asked to open a device that was not a file. For support for devices like 'com1:' or 'lpt1:', call CreateFile, then use the FileStream constructors that take an OS handle as an IntPtr."

I'm converting an Old VB6 project to VS.NET. This code in VB6 works with no problem:

Open "\.0.0.1\ZebraLP2844" For Output As #1

strTemp = "N" & vbCrLf ''' Clear buffer
strTemp = strTemp & "q811" & vbCrLf ''' Label Width in dots (2 inches)
strTemp = strTemp & "Q1217,1" & vbCrLf ''' Label height and gap in dots (1 inch)
strTemp = strTemp & "S" & Trim(Me.strSpeed) & vbCrLf
strTemp = strTemp & "D" & Trim(Me.strDensity) & vbCrLf
strTemp = strTemp & "ZT" & vbCrLf ''' Direction
strTemp = strTemp & "OD" & vbCrLf ''' Direct Thermal mode
strTemp = strTemp & "A25,12,0,4,1,1,N,""" & sFirstLine & """" & vbCrLf
strTemp = strTemp & "A25,45,0,4,1,1,N,""" & sSecondLine & """" & vbCrLf
strTemp = strTemp & "A25,78,0,4,1,1,N,""" & sThirthLine & """" & vbCrLf
strTemp = strTemp & "P" & Trim(intQty)
''' End of the EPL2 code

Print #1, strTemp
Close

Any help on how to send this stream/string/file to my shared printer using VS.NET would be greatly appreciated!!

Re: Shared Printer (send it a string)

Dave Kreskowiak8-Jan-07 9:17

Dave Kreskowiak

8-Jan-07 9:17

You can't use the File Stream objects to do this. They can only be used on actual files.

You're looking for something more like this[^] example.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Image Comparision

ParticleBoy8-Jan-07 8:11

ParticleBoy

8-Jan-07 8:11

I need a way to tell if 2 images are the same. more specifically, i need to know if 2 screen shots taken less than one second apart are the same or are different. I have tryed using the Image1.Equals(Image2) but this apparently just compares objects and not the data contained with in them. I found some obscure code on sourceforge, but im not sure i will be able to convert it to do what i want it to do. Also I am assuming that if i take 2 screen shots and nothing on the screen has changed, that the 2 resulting images should be identical pixel for pixel. I could be wrong on this part, but i have no way to test this as of yet. suggestions please.

Re: Image Comparision

Christian Graus8-Jan-07 9:13

Christian Graus

8-Jan-07 9:13

My image processing articles show how to access the bits of a bitmap. Then it's a snap to iterate over them and see if any have changed.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Database Error

Karma312518-Jan-07 8:06

Karma31251

8-Jan-07 8:06

ok so i am making a program with VB 2005 Express Edition and an Access database connected to it. when i run the program in the IDE it works fine but when i install it and run it, it talks about not being able to find the database. Now my question is... when you make a program with a database in the resource file, isn't the program supposed to copy to database to where ever it is supposed to read from and if it isnt then where\how to i get the program to copy and read the database upon installation. Also, i am keeping on the back burner the fact that when i install the program i want to be able to go into the database and change information and/or be able to print reports on the data.
the error:
upon startup the program cannot find the database and is looking in a folder that the program creates on its own(i didnt programmably make it)
the folder:
c:\Documemts and Settings\myUser\Local Settings\Apps\2.0\Data\993YD61J.131\C9JHJHC1.JGY \star..tion_8549497152147e43_0001.0000_603d66f8611c4d37\Data\Resources\

now why would it be looking there of all places and how can i correct this problem, this tis the knowledge i seek! lol
thanks
Joshua

Re: Database Error

Dave Kreskowiak8-Jan-07 9:13

Dave Kreskowiak

8-Jan-07 9:13

You have to include the .MDB file in the installation project and make sure that it get's placed in the folder that your app is expecting. There is nothing that does this automatically. It's just another file, like you app's .EXE, that you're responsible for in the install.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: Database Error

Karma312519-Jan-07 4:02

Karma31251

9-Jan-07 4:02

Ok so how would i add it i mean im using VB 2005 Express and i dont know if thats even an option, if it is i cant find it. Id ont think they give you a lot of options in the free version. anyone know a good How To on attach a data to an installation file?

Re: Database Error

Dave Kreskowiak9-Jan-07 12:32

Dave Kreskowiak

9-Jan-07 12:32

Well, I played with ClickOnce for a little bit. It doesn't look like you can add the extra file. I actually have no idea if you can or can't. I don't use ClickOnce for any of my deployments.

Dave Kreskowiak
Microsoft MVP - Visual Basic

MDI Forms

Jason Holland8-Jan-07 7:44

Jason Holland

8-Jan-07 7:44

Is there a way to make all children forms see the MDI left as anything other than 0. For instance if I wanted to make all child forms left=150, is there a way to set a property of the MDI form to 150.

Re: MDI Forms

nlarson118-Jan-07 8:02

nlarson11

8-Jan-07 8:02

'routine in the mdi
Sub ChangeLocation(iLeft as int16)

For Each ChildForm As Form In Me.MdiChildren
ChildForm.left = iLeft
Next

end sub

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.