Hall of Fame

1. lherrou5,500
2. garycutri5,050
3. upul0072,500
3. giltjr2,500
3. Shekhar2...2,500
6. Darr2472,360
7. imarshad2,000
7. PUNKY2,000
7. alexey_g...2,000
7. MicheleM...2,000
7. mayank_...2,000
7. GreatGerm2,000
7. rrjegan172,000
7. kitts2,000
15. aman07111,600
16. grimzbane1,500
16. dave4dl1,500
16. Meff1,500
16. masheik1,500
16. srujan11,500
21. Mikal6131,400
21. nobus1,400
23. ryan801,200
24. leew1,000
24. murphey21,000
24. noci1,000
24. GLCompu...1,000
24. mrjoltcola1,000
24. shahvikas1,000
24. Mestha1,000
24. Magadu1,000
24. ikalmar1,000
24. ShakerBr...1,000
24. Ituser1,000

1. imarshad45,792
2. Meff23,192
3. drelectro16,934
4. jenmir13,250
5. upul00712,650
6. SimonTay9,553
7. Mikal6139,410
8. Fisman7,575
9. keyurkarnik7,500
10. Darr2475,710
11. lherrou5,500
12. garycutri5,050
13. giltjr4,500
14. BigRat4,350
15. vilia4,000
16. Nagavali3,868
17. Sembee3,668
18. jmsousa3,628
19. Kurt_Bra...3,600
20. fajar793,500
21. arvep3,464
22. ALogvin2,800
23. le-maheux2,672
24. PUNKY2,500
24. KiyamKadir2,500
24. Shekhar2...2,500

	[x] Posted via EE Mobile
	Search, ask, and monitor your questions on the go with EE Mobile. Visit Experts Exchange from your mobile device and never be out of touch again.

Question

	[x] Attachment Details

[x]

The Solution Rating System

With so many solutions, how can you tell which solutions are most likely to help you and which ones are not? To provide you with a tool to use, we rate our solutions based on various elements that most accurately determine if a solution is a quality solution. To explain what factors affect the solution rating, here are the elements we take into consideration when formulating our solution rating.

The Grade of the Solution
The Zone Rank of the Expert Providing the Solution
The Number of Author and Expert Comments
The Number of Experts Contributing
The Feedback of the Community

Your Input Matters
Because of the way the system is set up, the most important variable in this equation is you. As a member of Experts Exchange, you are able to cast your vote on the quality of the solutions in regard to how complete, accurate, helpful and easy to understand each solution is. When you provide your feedback, each rating is adjusted accordingly. So, if you see a solution that has a poor rating that you think is a good solution, let us know by rating it. As you do, the rating will be adjusted and will become more accurate for other members of our site.

If you have any suggestions that you would like to make for our rating system, please ask a question in the Suggestions Zone of Community Support.

Thank you!

7.2

Unexplained connection drop in the middle of an FTP transmission using GPRS

Asked by Pirie in General Packet Radio Service (GPRS), Microsoft Visual Basic.Net, Windows MobileProgramming

Tags: vb .net

I have written two applications that communicate with each other via wireless GPRS. One of these applications runs on a Pocket PC under WM5 or WM6 and the other runs on a desktop. Both programs were developed using Visual Basic .Net under Visual Studio 2005.

The desktop application works as a server and continuously 'listens' for the Pocket PC application wanting to connect. The PPC application then requests connection with the desktop app. After the connection is accepted, the PPC app sends a file to the desktop app. To achieve this, an FTP connection is opened and the file is sent as a stream to the desktop app.

The problem:

The problem is that, for large files, the open connection is consistently dropped for some reason in the middle od the transmission. When it happens, it is always when the nws.Write statement in the enclosed code snippet is executed. For small data files there is no problem. The problem occurs after "nws.Write has been executed a few times.

It seems to me that the problem is connected with some kind of "maximum duration of transmission" setting. I conclude this since when the PPC is merely in a GPRS area, the connection always seems to be dropped about 15 seconds into the transmission. However, when I am in an area where HSDPA is available and send the same file the transmission gets much further.

There is no timeout explicitely programmed in the application.

I would appreciate any help in solving this (for me) tricky problem.

View the Solution FREE for 30 Days

         
           
             1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:

           
           
             The following is the source code within the PPC app  which sends the 'file to the server program in the desktop computer: 
 
Try
     Dim BufferSize As Integer = FtpClient.ReceiveBufferSize
 
     nws = FtpClient.GetStream
     If Not nws.CanWrite Or Not nws.CanRead Then GoTo ExitSub
     '---open the file
     Dim fs As New FileStream(FtpFileName, FileMode.Open, FileAccess.Read)
     Dim bytesToSend(CInt(fs.Length) - 1) As Byte
 
     ' Voortgangsscherm tonen
      Dim FileName As String = Strings.Right(FtpFileName, FtpFileName.Length - Strings.InStrRev(FtpFileName, "\"))
     myVoortGang.Visible = True
     myVoortGang.text = TEKST(1033) & " " & FileName  ' 1033="Upload"
     myVoortGang.ProgressBarMax = CInt(fs.Length)
     myVoortGang.ProgressBarValue = 0
     Invoke(delUpdateVoortgang, myVoortGang)
 
     Dim numBytesRead As Integer = fs.Read(bytesToSend, 0, bytesToSend.Length)
     Dim totalBytes As Integer = 0
     For i As Integer = 0 To CInt(fs.Length \ BufferSize)
         '---send the file
         If fs.Length - (i * BufferSize) > BufferSize Then
             nws.Write(bytesToSend, i * BufferSize, BufferSize)
             totalBytes += BufferSize
         Else
             nws.Write(bytesToSend, i * BufferSize, CInt(fs.Length) - (i * BufferSize))
             totalBytes += CInt(fs.Length) - (i * BufferSize)
         End If
         myVoortGang.Visible = True
         myVoortGang.ProgressBarValue = totalBytes
         Invoke(delUpdateVoortgang, myVoortGang)
     Next
     fs.Close()
     nws.Close()
     FtpClient.Close()
     Catch ex As Exception
          GoTo ExitSub
End Try
 
This is received by the following source code in the desktop application::
 
Dim TimeStart As DateTime = Now
Do
     If nws.DataAvailable Then
          'nieuwe data : timeout verlengen
          TimeStart = Now
          '---read the incoming data
          Dim bytesRead As Integer = nws.Read(data, 0, FtpClient.ReceiveBufferSize)
          totalBytes += bytesRead
          fs.Write(data, 0, bytesRead)
     End If
Loop While CInt(Now.Subtract(TimeStart).TotalSeconds) < 2 And totalBytes <> lsFileSize

           
         

20091111-EE-VQP-92 / EE_QW_2_20070628

Unexplained connection drop in the middle of an FTP transmission using GPRS

Asked by Pirie in General Packet Radio Service (GPRS), Microsoft Visual Basic.Net, Windows MobileProgramming

Tags: vb .net

About this solution