winsock question

[guyjasper]

hi everyone, i have this really annoying problem. hope you guys could help me out.

i have a multi client chat program that uses winsock. in the server side, i have an array of winsocks. once a client connects, a new instance of winsock is loaded to accept that connection request. the code looks like the example below:

Private Sub sckServer_ConnectionRequest(index As Integer, ByVal requestID As Long)
   If index = 0 Then
      intWIndex = intWIndex + 1
      
      Load sckServer(intWIndex)
      sckServer(intWIndex).Accept requestID
      
      AddLog "Socket connection request accepted -> index = " & intWIndex
End If

now my problem is, in some time while the program is running, some of the winsock in the server gets this error ''Connection is aborted due to timeout or other failure" but in the client side there is no winsock error for that particular connection. i have this code to handle this error :

Private Sub sckServer_Error(index As Integer, ByVal Number As Integer, _
   Description As String, ByVal sCode As Long, ByVal Source As String, ByVal _
   HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
   
   If index = 0 Then Exit Sub
   
   'close connection
   sckServer(index).Close
   
   'unload socket
   Unload sckServer(index)
End Sub

in the client side, whenever a winsock error occurs, i close the connection and i have a timer enabled so that the client would automatically try to reconnect to the server. but since no winsock error occurred, the client will not try to reconnect.

do you guys have any idea why no error event fired in the client side? how can i work around this problem? any help would be greatly appreciated.

[wildcat_2000]

generally speaking it is the client who is supposed to close the connection, while servers close the connection only on timeouts.

therefore: i would suggest to do some check on the client side on the winsock CLOSE event.

cheers,

wc.

[guyjasper]

that was quick

well, isn't it already handled in my error event in the server? when i close the connection from the server, doesn't the client catch this? what happens if i unload the winsock control from the server? will an error event occur in the client?

i really need help on this one so i hope you guys can shed some light i have been trying to figure out how to resolve this for weeks already ....

[wildcat_2000]

no errors, but the close event should fire up. as i suggested, try catching that and perform a check to see whether it is necessary or not for the client to re-open a connection.

[guyjasper]

well, in my client app, i had code for the close and error events but non of them fired when i closed the connection from the server and unloaded the winsock control

in the server side, is it a good practice to unload a winsock control that have been closed? and when the client tries to reconnect, load a new instance of the winsock control? and when a connection request is received, do i have to specify the localport for the winsock control that would accept that connection?

thanks for the reply...

[wildcat_2000]

in the server side, is it a good practice to unload a winsock control that have been closed?

yes.

and when the client tries to reconnect, load a new instance of the winsock control?

yes.

and when a connection request is received, do i have to specify the localport for the winsock control that would accept that connection?

i would check this out if i were you

cheers,

wc.

[guyjasper]

i tried downloading the source code from the link you posted... well, it doesn't have any error handling routines for the winsock control.

when a connection has been established between a client and a server, and then an error occurred in the server, what will happen to the connection now? i have searched many web sites but i haven't seen any example on how to properly handle this kind of situation. most of the examples i've found just displays the error message on a message box, and that's it. arrggghh!!!

[wildcat_2000]

guy, as suggested:

1. if an error occurs on the server, make it close down the connection and unload the winsock control;

2. on the client, on the ON_ERROR and the CLOSE event make your error routine checks.

the code was to show you how to handle your port question.

[guyjasper]

yes, i already have error handling routines on my client.
i have the ff. codes on my client:

Private Sub sckClient_Close()
   AddLog "*** frmMain.sckClient_Close()"
   
   'set label
   lblSocketState.Caption = "Socket Last State = 'Closed'"
   lblSocketState.Refresh
   
   'try to reconnect to server
   AddLog "tmrConnect enabled."
   tmrConnect.Enabled = True
End Sub
 
Private Sub sckClient_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
   AddLog "*** frmMain.sckClient_Error('" & Number & " - " & Description & "')"
   
   'set label
   lblSocketState.Caption = "Socket Last State = 'Error'"
   sckClient.Close
   tmrConnect.Enabled = True
End Sub
 
Private Sub tmrConnect_Timer()
   sckClient.Close
   sckClient.Connect RemoteHostIP, RemotePort
End Sub

i set tmrConnect interval to 2000 (2 secs). i've tested this code and it works perfectly but that was not the problem. in my program, for some reason, the error event occurred in the server side but in the client side, there was no error event it's really confusing. that is why my client doesn't try to reconnect to the server because maybe it thinks that it is still "connected" to server. while in the server, it already closed and unloaded the winsock control for that connection and is waiting for the client to try to reconnect.