File Transfer between PDA & Pc

Hello All,

I'm trying to build a very simple program that starts communication between Pocket Pc and Pc using Visual Basic . NET and its emulator.
Would you pls show me the easiest way to strat such a thing? if there is any sample code or tutorial I would apprciate it also.

Thanks in advance

Well, this might not be even close to what you are asking about, but here's a class I wrote to handle transfering XML strings from a PDA program. The same class can't be used on the PC side, but the functionality of the PC side item isn't much different.

VB Code:

'This class opens a file with the name passed into the constructor. It then
'either writes or reads one item to it for each write/read item call.
'This Class assumes the file will be located in the AppPath() folder.
Public Class FileDataStorePDA
    Private fileName As String
    Private bisValid As Boolean
    Private readValid As Boolean
    Private sWriter As System.IO.StreamWriter
    Private sReader As System.IO.StreamReader
    Private clearFlag As Boolean
 
#Region "Constructors and Destructors"
    Public Sub New(ByVal st1 As String)
        st1 = AppPath() & "\" & st1
 
        Try
            sWriter = System.IO.File.AppendText(st1)
            bisValid = True
            fileName = st1
            clearFlag = False
        Catch ex As Exception
            bisValid = False
            clearFlag = True
        End Try
 
    End Sub
 
    Public Sub Dispose()
        Try
            sReader.Close()
        Catch ex As Exception
            'Nothing needs to be done here.
        End Try
 
        Try
            sWriter.Close()
        Catch ex As Exception
            'Nothing needs to be done here, either.
        End Try
    End Sub
#End Region
 
#Region "Public"
    Public Function WriteItem(ByVal st1 As String) As Boolean
        If bisValid Then
            If clearFlag Then
                clearFlag = False
                sWriter.Close()
                System.IO.File.Delete(fileName)
                sWriter = System.IO.File.AppendText(fileName)
            End If
            sWriter.WriteLine(st1)
            WriteItem = True
        Else
            If readValid Then
                Try
                    sReader.Close()
                    If clearFlag Then
                        clearFlag = False
                        System.IO.File.Delete(fileName)
                    End If
                    sWriter = System.IO.File.AppendText(fileName)
                    sWriter.WriteLine(st1)
                    WriteItem = True
                Catch ex As Exception
                    'Don't know if I really want this to do anything.
                    WriteItem = False
                Finally
                    readValid = False
                    bisValid = True
                End Try
            Else
                WriteItem = False
            End If
        End If
    End Function
 
    Public Function ClearFile()
        clearFlag = True
    End Function
 
    Public Function ReadItem() As String
        If readValid Then
            Try
                ReadItem = sReader.ReadLine
                If ReadItem Is Nothing Then
                    ReadItem = ""
                End If
            Catch ex As Exception
                MsgBox("A problem occurred with reading the file:" & vbNewLine & ex.Message, MsgBoxStyle.Information, "Problem")
                ReadItem = ""
            End Try
        Else
            If bisValid Then
                Try
                    sWriter.Close()
                    sReader = New System.IO.StreamReader(fileName, System.Text.Encoding.ASCII)
                    ReadItem = sReader.ReadLine
                    readValid = True
                Catch ex As Exception
                    MsgBox("Can't read item:" & vbNewLine & ex.Message, MsgBoxStyle.Exclamation, "Problem Reading")
                    ReadItem = ""
                    readValid = False
                Finally
                    'Invalidate the reading, anyways.
                    readValid = True
                    bisValid = False
                End Try
            End If
        End If
    End Function
 
    Public Function CanRead() As Boolean
        CanRead = readValid
    End Function
 
    Public Function CanWrite() As Boolean
        CanWrite = bisValid
    End Function
 
#End Region
 
#Region "Private"
    'The function that gets the path of the application.
    Private Function AppPath()
        AppPath = System.IO.Path.GetDirectoryName(Reflection.Assembly.GetCallingAssembly.GetName.CodeBase.ToString)
    End Function
#End Region
 
End Class

Thanks alot Shaggy, I want to ask if I can use this class in smartdevice project ( emulator ) of VB .NET. Pardon my question because I'm very newbie using such platform :blush: :)

One more thing. I found chatting application written using VB .NET it consists of three parts: client, server, inbetween, so I wonder if I can use the PC as server. Pocket Pc as client, and then modify the project so I can transfer files btwn them ?

As for the emulator....I don't know. I would expect that it would work, but the emulator is an odd item. If you can avoid using it, do so, but that requires actually having a PDA to test things on.

As for the client/server. I believe you HAVE to use the PC as the server because PDA's don't allow listening on a port. That means that only the PC can be set to listen for input.

I suspect that very little needs to be changed on the code I posted to transfer text files (maybe nothing), or for chat applications. However, all incoming text is interpreted into a string, since I was just moving XML.

If you liked that, here's the PC part of it. The idea is that the connection class runs in it's own thread. This is mostly untested, and has a bunch of stuff that is specific to the database I was using, but it would be a start.

VB Code:

Public Class PDAviaTCP
    Private curListen As System.Net.Sockets.TcpListener
    Private quitFlag As Boolean
    Private myTimer As System.Windows.Forms.Timer
    Private lSock As System.Net.Sockets.TcpClient
    Private netStream As System.Net.Sockets.NetworkStream
    Private linOpt As System.Net.Sockets.LingerOption
    Private bTimedOut As Boolean
 
#Region "Constructors and Destructors"
 
    Public Sub New()
        curListen = New System.Net.Sockets.TcpListener(System.Net.IPAddress.Any, 2000)
        quitFlag = True
        'Create the timer
        myTimer = New System.Windows.Forms.Timer
        'Need to tell it where to send time tick messages.
        AddHandler myTimer.Tick, AddressOf TimerEventProcessor
 
        'This is set so that we can know the status if nothing is received.
        bTimedOut = False
 
        ' Sets the timer interval to 5 seconds.
        myTimer.Interval = 5000
        myTimer.Enabled = False
        linOpt = New System.Net.Sockets.LingerOption(True, 5)
    End Sub
 
    Public Sub dispose()
        myTimer.Dispose()
        curListen.Stop()
        If Not lSock Is Nothing Then
            lSock.Close()
        End If
    End Sub
#End Region
 
#Region "Public Functions"
    'StartListening puts the TCPListener class into listening mode. This must be called
    'for a connection to be received.
    Public Sub StartListening()
        Try
            curListen.Start()
        Catch ex As Exception
            'Regardless of the exception, this may be ok.
            MsgBox("Exception was thrown during start." & vbNewLine & vbNewLine & ex.Message, MsgBoxStyle.Information, "Possible Issue")
        End Try
    End Sub
 
    'This function simply checks for a connection, but does not do anything except return
    'true if a connection is pending.
    Public Function CheckForConnection() As Boolean
        Try
            CheckForConnection = curListen.Pending
        Catch
            CheckForConnection = False
        End Try
    End Function
 
    'This function simply accepts the connection and stops the listener.
    Public Function GetConnection() As Boolean
        Try
            If curListen.Pending Then
                lSock = curListen.AcceptTcpClient
                lSock.LingerState = linOpt
                netStream = lSock.GetStream
                curListen.Stop()
                GetConnection = True
            Else
                GetConnection = False
            End If
        Catch ex As Exception
            GetConnection = False
        End Try
    End Function
 
    'Stops listening without bothering with whether or not a connection is available.
    Public Sub StopListening()
        curListen.Stop()
    End Sub
 
    'Use this to send data to the socket. No check is made to see that
    'the socket is available. The return is false if any exceptions are raised.
    Public Function SendData(ByVal st1 As String) As Boolean
        Dim sendBuff(2048) As Byte
 
        'Try
        sendBuff = System.Text.Encoding.Default.GetBytes(st1.ToCharArray())
        netStream.Write(sendBuff, 0, sendBuff.GetLength(0))
        SendData = True
        'Catch ex As Exception
        SendData = False
        'End Try
 
    End Function
 
    'Use this to get data from the socket. This will time out in 5s.
    Public Function RetrieveData() As String
        Dim recBuff(2048) As Byte
        Dim recCount As Integer
        Dim st1 As String
        Dim hasRead As Boolean
 
        hasRead = False
        'Get ready to read.
        quitFlag = True
        myTimer.Enabled = True
        Try
            Do While quitFlag
                If netStream.DataAvailable Then
                    recCount = netStream.Read(recBuff, 0, recBuff.GetLength(0))
                End If
                If recCount > 0 Then
                    hasRead = True
                    myTimer.Enabled = False
                    'Turn it into a string.
                    st1 &= System.Text.Encoding.ASCII.GetString(recBuff, 0, recCount)
                    st1 = st1
                    'Clear out the buffer.
                    recBuff.Clear(recBuff, 0, recBuff.GetLength(0))
                    recCount = 0
                Else
                    'If hasRead is set, then something has been received, but the last loop
                    'returned nothing. Therefore, we are done reading.
                    If hasRead Then
                        'This is simply cleared to stop the loop.
                        quitFlag = False
                    End If
                    'DoEvents, but only if nothing is coming in!
                    Application.DoEvents()
                End If
            Loop
        Catch ex As Exception
            'Nothing can be done here, but that's ok.
            MsgBox(ex.Message)
        End Try
 
        'Get out.
        Me.bTimedOut = False
        RetrieveData = st1
    End Function
 
    'If this is true, then the time event fired. Basically, this means that if
    'RetrieveData() returned an empty string, it was because of timing out.
    Public Function TimedOut() As Boolean
        TimedOut = Me.TimedOut
    End Function
 
#End Region
 
#Region "Private Functions"
 
    'The timer is used to stop the endless loop in RetrieveData(), and for no other 
    'purpose. If the event fires, the bTimedOut variable is set.
    Private Sub TimerEventProcessor(ByVal myObject As Object, ByVal myEventArgs As EventArgs)
        myTimer.Enabled = False
        quitFlag = False
        Me.bTimedOut = True
    End Sub
 
 
#End Region
End Class
 
 
 
Public Class ThreadedConnection
    Private theThread As System.Threading.Thread
    Private mDBHolder As dbHolder
    Private mPDAvia As PDAviaTCP
    Private Shared mWriteDone As System.Threading.ManualResetEvent
 
    Public Sub New()
        theThread = New System.Threading.Thread(AddressOf DoConnection)
 
        'This may be somewhat sketchy, but it should work just fine.
        mDBHolder = dbC.Copy
        theThread.IsBackground = True
        mPDAvia = New PDAviaTCP
        mWriteDone = New System.Threading.ManualResetEvent(False)
 
    End Sub
 
    Public Sub Dispose()
        StopConnection()
        mWriteDone.Close()
        mPDAvia.dispose()
        mDBHolder.Dispose()
    End Sub
 
    'This checks the database in the connection thread, and if it is valid, the thread
    'is started.
    Public Function StartConnection() As Boolean
 
        If mDBHolder.IsValid Then
            theThread.Start()
        End If
        StartConnection = mDBHolder.IsValid
    End Function
 
    Public Sub StopConnection()
        'The event will be signaled (go ahead) throughout, with the exception of writing
        'to the db. For that alone it will be unsignaled (wait). Once the write is complete
        'the event will be signaled.
        mWriteDone.WaitOne()
 
        'At which point, it would be a good idea to stop the comport from listening.
        mPDAvia.StopListening()
        'And end the thread.
        theThread.Abort()
    End Sub
 
 
    Private Sub DoConnection()
        Dim st1 As String
        Dim st2 As String
        Dim v As Integer
        Dim outData As String
 
        'First make the string data for outputting.
        outData = mDBHolder.CreateData()
        mPDAvia.StartListening()
 
        mWriteDone.Set()
        Do
            Do
                Application.DoEvents()
            Loop While Not mPDAvia.CheckForConnection
 
            'If you get here, then a connection is ready.
            If mPDAvia.GetConnection() Then
                'Send the type info across.
                mPDAvia.SendData("1")
                st1 = mPDAvia.RetrieveData
 
                'Next, send out the output data.
                mPDAvia.SendData(outData)
 
                'Now, st1 holds either 1 (no data) or 4 (new data coming) or 5 (all data coming)
                v = Val(st1)
 
                If v > 1 Then
                    'Now the data coming back should be received.
                    st2 = mPDAvia.RetrieveData
                    mWriteDone.Reset()
                    mDBHolder.UpdateTablesWithXML(st2)
                    mWriteDone.Set()
                End If
            End If
 
            'Now it is necessary to start listening again.
            mPDAvia.StartListening()
        Loop While True
    End Sub
 
End Class

Thanks alot Shaggy. I'm trying nw to run your code and see how to modify it to let it transfer file instead of XML strings. and I'll come back when a question come up ;)

Thanks :)

Hello Shaggy,

The pc side code "PDAviaTCP" gave me an error with "dbHolder". I thought it is a predefine class but is isn't, Where I can found it?

the other thing is what is the interface looks like either for Pc or PDA sides ?

Thanks :)

You want to get rid of that dbHolder, and anything related to it. That's a class I wrote to manage the database connection for the program. It has no bearing on any other program.

As for a UI, there really isn't one related to those classes.

In general, any PDA program I write uses a single form (or more if it gets REALLY big). The form has many panels on it that are sized to the size of the PDA screen. All panels are initially set to be off screen, with the top set around 300, and the left set at 0. The panels take the place of forms, since moving a panel is very fast, while loading a form is very slow (on a PDA).

The basic outline is that there is a state variable called theState (or something like that), and a sub called ShowPanel() that just has a switch on theState. The switch sets the top value for the right panel to 0, so that it becomes visible.

This isn't my idea, by the way, I got it from a book on DB programming for the .NET CF by Rob Tiffany. The idea works great.

Thanks again Shaggy,

May I know the title of the book?

You're in luck, I happen to have the title with me (though not the book):

SQL Server CE Database Development with the .NET Compact Framework by Rob Tiffany. Published by aPress.

While the topic is indeed databases, he's got some strong opinions on PDA program design, and shares them in the first few chapters. Nothing earth-shaking, but I certainly like that panel-swapping alternative to form loading.