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Introduction

Before we start

The server

Load the sample project ZipServer.

To start accepting new connections, we have to set the property ZipSrv.ListenningPort (2222 in our case) and call the method ZipSrv.Start(). In order to make the compression work, we have to write handlers for the events OnNeedZip, OnZipDone, OnNeedUnzip, and OnUnzipDone.

OnNeedZip

OnNeedZip event notifies about a client's request and asks for permission to start a compression operation.

  'Request for zipping
  Private Sub ZipSrv_OnNeedZip(ByVal sender As System.Object, ByVal e As AxbsFileServerSDK.IBSZipSrvXEvents_OnNeedZipEvent) Handles ZipSrv.OnNeedZip
    e.aOkay = True           'permit the operation
    e.aRoot = App_Path()     'give our application folder as root folder
    LogMsg(GetUsername(e.aHandle) + ": start zipping to " + e.aPath)
  End Sub

  'The zip operation is completed
  Private Sub ZipSrv_OnZipDone(ByVal sender As System.Object, ByVal e As AxbsFileServerSDK.IBSFileSrvXEvents_OnZipDoneEvent) Handles ZipSrv.OnZipDone
    LogMsg(GetUsername(e.aHandle) + ": finish zipping - code " + Str(e.aCode))
  End Sub

  'Request for unzipping
  Private Sub ZipSrv_OnNeedUnzip(ByVal sender As System.Object, ByVal e As AxbsFileServerSDK.IBSFileSrvXEvents_OnNeedUnzipEvent) Handles ZipSrv.OnNeedUnzip
    e.aOkay = True           'permit the operation
    e.aRoot = App_Path()     'give our application folder as root folder
    LogMsg(GetUsername(e.aHandle) + ": start unzipping from " + e.aPath)
  End Sub

  'The unzip operation is completed
  Private Sub ZipSrv_OnUnzipDone(ByVal sender As Object, ByVal e As AxBSZipSrvLib.IBSZipSrvXEvents_OnUnzipDoneEvent) Handles ZipSrv.OnUnzipDone
    LogMsg(txtRmtAddr.Text + ": finish unzipping - " + Str(e.aCode))
  End Sub

The client

'Initiate a connection request
Private Sub btnConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnect.Click
  If fConnect.ShowDialog <> DialogResult.OK Then Exit Sub

  If fConnect.txtKey.Text() > "" Then
    ZipCln.SecurityMode = 2  'shared secret key
    ZipCln.SecretKey = fConnect.txtKey.Text
  Else
    ZipCln.SecurityMode = 0  ' no encryption
  End If
  If Not ZipCln.Connect(fConnect.txtHost.Text, Val(fConnect.txtPort.Text)) Then
    MsgBox("Error Code: " + Str(ZipCln.LastError))
  End If

  UpdateStatus()
End Sub

  'Start the zip operation
  Private Sub btnZip_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnZip.Click
    Dim Nm As String

    Nm = InputBox("Zip file name", "Zipping")                'ask the user for the zip file name
    If Nm = "" Then Exit Sub 'canceled by the user

    If ExtractFileExt(Nm) = "" Then
      Nm = Nm + ".zip"
    End If

    If ZipCln.Zip(AddSlash(txtFolder.Text) + Nm, AddSlash(txtFolder.Text) + lvFiles.SelectedItems(0).Text) Then
      'the request is accepted
      NowZip = True                   'raise the flag   
      ZipFile = Nm                    'remember the zip file
      ZipFol = txtFolder.Text         'remember the current folder
      txtZip.Text = "Handshaking..."
    Else
      CheckError(ZipCln.LastError)   'the request is rejected
    End If
    UpdateStatus()
  End Sub

  'Progress information is available for the zip operation
  Private Sub ZipCln_OnZipProgress(ByVal sender As System.Object, ByVal e As AxBSFileClientSDK.IBSFileClnXEvents_OnZipProgressEvent) Handles ZipCln.OnZipProgress
    'Show the current byte count and the total amount of bytes (low 32 bits)
    txtZip.Text = ZipFile + " - " + Str(e.aByteCountLo) + "/" + Str(e.aByteTotalLo)
  End Sub

  'The zip operation is completed
  Private Sub ZipCln_OnZipDone(ByVal sender As System.Object, ByVal e As AxBSFileClientSDK.IBSFileClnXEvents_OnZipDoneEvent) Handles ZipCln.OnZipDone
    If e.aCode = 0 Then
      'success
      txtZip.Text = ZipFile + " - " + "Done."
      If ZipFol = txtFolder.Text Then
        ListFolder()           'refresh the file list
      End If
    Else
      txtZip.Text = ZipFile + " - " + "Aborted: " + ErrorText(e.aCode)     'there is an error, describe it
    End If
    NowZip = False
    UpdateStatus()
  End Sub

  'Start the unzip operation
  Private Sub btnUnzip_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUnzip.Click
    Dim Nm As String

    'ask the user for the extraction folder
    Nm = InputBox("Extract to folder (leave blank for current):", "Unzipping")
    If Nm = "" Then Exit Sub 'canceled by the user

    If ZipCln.Unzip(AddSlash(txtFolder.Text) + lvFiles.SelectedItems(0).Text, AddSlash(txtFolder.Text) + Nm) Then
      'the request is accepted
      NowUnzip = True                                  'raise the flag   
      UnzipFile = Nm                                   'remember the unzip file
      UnzipFol = txtFolder.Text                       'remember the current folder
      txtUnzip.Text = "Handshaking..."
    Else
      CheckError(ZipCln.LastError)   'the request is rejected
    End If
    UpdateStatus()
  End Sub

  'Progress information is available for the unzip operation
  Private Sub ZipCln_OnUnzipProgress1(ByVal sender As System.Object, ByVal e As AxBSFileClientSDK.IBSFileClnXEvents_OnUnzipProgressEvent) Handles ZipCln.OnUnzipProgress
    'Show the current byte count and the total amount of bytes (low 32 bits)
    txtUnzip.Text = UnzipFile + " - " + Str(e.aByteCountLo) + "/" + Str(e.aByteTotalLo)
  End Sub

  'The unzip operation is completed
  Private Sub ZipCln_OnUnzipDone(ByVal sender As System.Object, ByVal e As AxBSFileClientSDK.IBSFileClnXEvents_OnUnzipDoneEvent) Handles ZipCln.OnUnzipDone
    If e.aCode = 0 Then
      'success
      txtUnzip.Text = UnzipFile + " - " + "Done."
      If UnzipFol = txtFolder.Text Then
        ListFolder()            'refresh the file list
      End If
    Else
      txtUnzip.Text = UnzipFile + " - " + "Aborted: " + ErrorText(e.aCode)     'there is an error, describe it
    End If
    NowUnzip = False
    UpdateStatus()
  End Sub

The bottom line

Remote file compression can be very useful in some situations, when a large amount of data must be exchanged across the Internet. This could be one of the simplest solution for that.

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