[RESOLVED] Multiple connections

[dlern]

I have a multiple client-server setup using VB 6.0 that is connecting upto 30 computers at once across a LAN using TCP/IP connection. After all the client computers are connected to the server computer, I was trying to broadcast a command to all the clients at once, but as I itterated through each winsock connection, the command would only being recieved by last computer which connected. Is there any way to do this so all the computers that are connected the receive the command?

for idx = 1 to 30
   Socket(idx).SendData CmndStrng
next

[opus]

What type of connection do you use?
TCP or UDP?

[dlern]

TCP and don't want to use the UDP broadcast method

[opus]

You say that the 30 computers are all connected, did check them all? (I let each of them send a message when connected to server. That way Im sure all are connected)
The sending code by itself seems okay to me (whatever that says)

[dlern]

Private Sub Form_Load()
    
    lblHostID.Caption = Socket(0).LocalHostName
    lblAddress.Caption = Socket(0).LocalIP
    Socket(0).LocalPort = 1007
    sServerMsg = "Listening to port: " & Socket(0).LocalPort
    List1.AddItem (sServerMsg)
    Socket(0).Listen
End Sub
 
 
Private Sub socket_Close(Index As Integer)
    sServerMsg = "Connection closed: " & "[" & Index & "]" & Socket(Index).RemoteHostIP
    List1.AddItem (sServerMsg)
    Socket(Index).Close
    Unload Socket(Index)
    iSockets = iSockets - 1
    lblConnections.Caption = iSockets
    
End Sub
 
Private Sub socket_ConnectionRequest(Index As Integer, ByVal requestID As Long)
    sServerMsg = "Connection request id " & "[" & sckCount & "]" & requestID & " from " & Socket(Index).RemoteHostIP
  If Index = 0 Then
    List1.AddItem (sServerMsg)
    sRequestID = requestID
    iSockets = iSockets + 1
    sckCount = sckCount + 1
    lblConnections.Caption = iSockets
    Load Socket(sckCount)
    Socket(sckCount).LocalPort = 1111
    Socket(sckCount).Accept requestID
    Debug.Print requestID
  End If
 
End Sub
 
Private Sub socket_DataArrival(Index As Integer, ByVal bytesTotal As Long)
    
        
    ' get data from client
    Socket(Index).GetData sRData, vbString
 
End Sub
 
Private Cmnd_click
for idx = 1 to 30
   Socket(idx).SendData CmndStrng
next
 
End sub

[dlern]

I have include the server code. Within the form, the number of active connections is listed as a label and a listbox displays as each client connects or closes.

So I do know all of the clients are connected, but the command only gets received my the most recently connected client (client form also displays the received data).

Any ideas?

[Pino]

i've only browsed the thread but try this,

for i = 0 to winsock.ubound - 1
    if winsock(i).state = sckconnected then
       winsock(i).senddata Data
    end if
  doevents
next i

Pino

[opus]

do all your connections share a single port on the serverside?
I think that is the problem!

[Pino]

opus is correct your code here needs changing.

Private Sub socket_ConnectionRequest(Index As Integer, ByVal requestID As Long)
    sServerMsg = "Connection request id " & "[" & sckCount & "]" & requestID & " from " & Socket(Index).RemoteHostIP
  If Index = 0 Then
    List1.AddItem (sServerMsg)
    sRequestID = requestID
    iSockets = iSockets + 1
    sckCount = sckCount + 1
    lblConnections.Caption = iSockets
    Load Socket(sckCount)
    Socket(sckCount).LocalPort = 1111
    Socket(sckCount).Accept requestID
    Debug.Print requestID
  End If

chang eit to this....

Private Sub socket_ConnectionRequest(Index As Integer, ByVal requestID As Long)
    
sServerMsg = "Connection request id " & "[" & sckCount & "]" & requestID & " from " & Socket(Index).RemoteHostIP
 
  Load Winsock(Winsock.UBound + 1)
  Winsock(Winsock.UBound).Accept RequestID
 
End Sub

Not the 100% best way but for 30 sockets you should be ok, and it will work

[dlern]

Pino, that fixed it perfectly. I can now send commands to individual clients or broadcast to all the connected clients.

Only, what is the problem with this method. What if I was connected to 100 clients, or 500?

Thanks Again!!!!!!

[Pino]

the code i gaev u will let you have 1 million clients connect (memory dependant)

Basicly its not so good because lets say we have 5 clients connected and client 3 leaves and so does client 1, thast 2 open slots not being used just munching memory, good code would search each slot to see if its free, but for now you dont need to concern yourself with that!

Pino

[CVMichael]

Look at the server side project in here:
VB - How to send a file using the Winsock control

That is how you properly accept connections. The server is re-using sockets that are closed, therefore saving memory.

[MagellanTX]

....I'm just adding my two cents here....

Instead of sending individual messages to each computer (especially if you get into the hundreds of connections) what about using a multicast address. This is not difficult to do in Visual Studio and is extremely efficient for sending one copy of a message to many computers (thousands, if your network can support it) simultaneously. This also solves the issue of computers leaving the network during the broadcast because the multicast mechanisms automatically adjust when clients join/leave the multicast domain.

The only caveat here is that if your computers are on different subnets you will need to make sure your routers support multicast routing.

[CVMichael]

He's using VB6, you can't do multicast in VB6...

[MagellanTX]

Whoops, was focusing on the issue as a whole...completely missed that important detail.