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VB Forum / Win API / January 2007vvb6 Winsock not receiving all data
This problem is driving me mad, and from this forum lot's of other people too! I'm using Winsock to send and receive data large amount's of data (1000's records) as a string. The first time I do this it seems to work fine. But if I refresh the data several times, eventually for some reason it can not get all the data sent. For your info I've included my DataArrival event. Private Sub ws1_DataArrival(ByVal bytesTotal As Long) Dim sDataBlock As String Dim temp As String iDataArrivals = iDataArrivals + 1 ws1.GetData sDataBlock sDataBlock = Replace(sDataBlock, vbCrLf, "") ' I've added this code so that when it recieves the last block of data, where iDataArrivals = 29 ' get some more data but it just returns "". If iDataArrivals = 29 And bytesTotal <> 8192 Then ws1.GetData temp MsgBox temp End If data = data & sDataBlock End Sub Any help would be appreciated, with code samples? Rob > This problem is driving me mad, and from this forum lot's of other > people too! [quoted text clipped - 30 lines] > > Rob Why are you counting how many times you receive data ie "iDataArrivals = 29" as you have no control over block size of the IP frames when presented to you?. If you are looking at 29, what happens if it takes 28 or 30? What I would do is to supply a specific, unique frame when you have finished sending data and then look for that frame when you receive the data. That way you know when you have finished receiving data.. Neil.. Rob, I put the if block for testing purposes -please ignore if this confuses you! The point is that a close event is firing before all the data has been received, and the last DataArrival event fires? Rob > Why are you counting how many times you receive data ie "iDataArrivals = 29" > as you have no control over block size of the IP frames when presented to [quoted text clipped - 5 lines] > > Neil.. What close event? > Rob, > [quoted text clipped - 15 lines] > > > > Neil.. The one that come's the windock component Private Sub ws1_Close() Dim iParts As Integer ws1.Close data = Split(data, "<%data%>") iParts = UBound(data) If iParts = 0 Then MsgBox "An Error Has Occured" Else data = data(1) End If recvd = True End Sub > What close event? > [quoted text clipped - 21 lines] > > > > > > Neil.. > The one that come's the windock component > > Private Sub ws1_Close() > Dim iParts As Integer > > ws1.Close That just looks ... off. I don't really have "my winsock hat on" right now, but I'm pretty sure that none of my code ever calls .Close on the receiving side. Seems pretty pointless and possibly obstructive. > data = Split(data, "<%data%>") > [quoted text clipped - 8 lines] > recvd = True > End Sub Bob -- >> The one that come's the windock component >> [quoted text clipped - 4 lines] > > That just looks ... off. No, it doesn't. The MSDN Library documentation advises it: <q> The Close Event occurs when the remote computer closes the connection. Applications should use the Close method to correctly close a TCP connection. </q> See: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/mswnsk98/html/v bevtCloseEvent.asp <snip> Sinna >>> The one that come's the windock component >>> [quoted text clipped - 16 lines] > <snip> > Sinna Note that those are two separate sentences. I'm sure it's a one-or-the-other situation. Do both, and the event code probably gets invoked twice, which, in the case of the code we've been looking at, would probably screw up the data buffer. ...Perhaps even leading the OP to think some of the data never arrived... Bob -- >>>> The one that come's the windock component >>>> [quoted text clipped - 26 lines] > > Bob Well... Speaking out of experience I do also have to call the Close routine from the Winsock Control, otherwise the connection stays up in a kind of tristate: State = tcpClosing. BTW: Why should the docs state '... to correctly close ...' the connection when documenting the Close Event. I've also noticed that invoking the Close routine doesn't raise the Close Event at all. Sinna All, Thanks for all your help! But I still haven't managed to get to the bottom of this problem, so any more feedback would be welcome. I tried a number of suggestions, but none of them worked, so I've written a 'work around'. In the end I pass '<end>' at the end of the string of records at the server, and now test for this in the global variable Data, in the close event. If it's not present, then i request the entire data, from scratch, again. It's not perfect, but it does seem to work! For your information, I've noticed the following. 1) Some times the last DataArrival event does not always contain the entire last chuck of data sent from the server, and the Close event will fire. Now from what some of you said the next DataArrival event that occurs should contain the missing data, but it never does! 2) I've noticed that during normal office hours the problem's occur, more frequently than outside! 3) On the server side I have PHP file that is uses an ODBC driver to run a SQL query to get the record's I required, and then pass then back to the client app, written in VB6, to displayed in an MSFlexGrid. Rob RobertTheBruce <robert_bruce@hargreaveslansdown.co.uk> schrieb im Beitrag <1169470447.438816.192830@m58g2000cwm.googlegroups.com>... > 1) Some times the last DataArrival event does not always contain the > entire last chuck of data sent from the server, and the Close event [quoted text clipped - 7 lines] > run a SQL query to get the record's I required, and then pass then back > to the client app, written in VB6, to displayed in an MSFlexGrid. As far as I can see your PHP script closes the connection as soon as it has sent the last data packet. I don't know anything about the machine on which you PHP script runs - but maybe this closing prevents the remaining data which are still in the queue from being sent. Instead try this: - After PHP has sent the last package of data it should enter a kind of 'listen mode' and wait for an acknowledgement of you VB application that it has recieved all data. If the acknowledgement isn't received within a certain time interval, the PHP script should close the connection terminate with an error. If it got the receipt it should close the connection and terminate successfull. - You VB application should acknowledge the receipt of all data by sending the PHP script a certain data sequence ('<ack>' or the like). If it hasn't recieved the data within a certain time interval it should close the connection and terminate with an error.  Signature---------------------------------------------------------------------- THORSTEN ALBERS Universität Freiburg albers@ uni-freiburg.de ---------------------------------------------------------------------- Sorry. I realised after sending the post that there was a close event!. It is something I have never used. It also appears that you have more code than you originally said. It would be better if you supplied ALL your code being controlled by Winsock as events can interact, Also what is resetting various parameters (Such as "data")? What is "data(1)" in the close event below ? > The one that come's the windock component > [quoted text clipped - 42 lines] >> > > >> > > Neil.. RobertTheBruce <robert_bruce@hargreaveslansdown.co.uk> schrieb im Beitrag <1169225840.961610.204860@a75g2000cwd.googlegroups.com>... > Private Sub ws1_Close() > Dim iParts As Integer [quoted text clipped - 8 lines] > recvd = True > End Sub Are you really sure that Close-Event can't be fired before the last DataArrival-Event has been fired? The Close-Event is fired when the remote computer closed the connection and not when the last byte of the data has been recieved. Maybe you should try this: Private Sub ws1_Close() Dim iParts As Integer Dim sDataBlock As String ' Insert something like this: If ws1.BytesReceived Then ws1.GetData sDataBlock sDataBlock = Replace(sDataBlock, vbCrLf, "") data = data & sDataBlock End If ws1.Close data = Split(data, "<%data%>") iParts = UBound(data) If iParts = 0 Then MsgBox "An Error Has Occured" Else data = data(1) End If recvd = True End Sub And ws1.Close is not necessary since the connection has already been closed. If it wouldn't have been closed the Close event wouldn't have been fires. Signature---------------------------------------------------------------------- THORSTEN ALBERS Universität Freiburg albers@ uni-freiburg.de ---------------------------------------------------------------------- > This problem is driving me mad, and from this forum lot's of other > people too! <cut> > ' I've added this code so that when it recieves the last block of > data, where iDataArrivals = 29 > ' get some more data but it just returns "". > If iDataArrivals = 29 And bytesTotal <> 8192 Then If you are sending 8192 bytes of data then that's what you need to wait for. It may come in 1 DataArrival or 8192 DataArrivals or anything in between and it can vary from run to run. Lose the requirement for 29 of them. SignatureReply to the group so all can participate VB.Net: "Fool me once..." |
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