B4X Requires Chilkat v11.0.0+

Transfer a File using Sockets (TLS or non-TLS)

See more Socket/SSL/TLS Examples

Demonstrates how to two programs, one a socket writer and the other a socket reader, can transfer a file. The connection can be TLS or a regular non-encrypted TCP connection. B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  On the sending side, we'll load the file into a BinData object and send.
'  On the receiving side, we'll read from the socket connection into a BinData, and save to a file.
'  This example assumes the file is not crazy-large, and that the entire contents
'  can fit into memory.  
'  (If the file is too large for memory, there are other ways to send. It just involves streaming or 
'  sending the file chunk-by-chunk..)

'  This section of code is for the sender.
Dim bdToSend As ChilkatBinData
bdToSend.Initialize
success = bdToSend.LoadFile("somePath/someFile.dat")
'  Assume success for the example...

Dim sndSock As ChilkatSocket
sndSock.Initialize("sndSock")
Dim bUseTls As Boolean = True
Dim port As Int = 5555
Dim maxWaitMs As Int = 5000
success = sndSock.Connect("some_domain_or_ip.com", port, bUseTls, maxWaitMs)
'  Assume success for the example...

'  Tell the receiver how many bytes are coming.
Dim numBytes As Int = bdToSend.NumBytes
Dim bBigEndian As Boolean = True
success = sndSock.SendInt32(numBytes, bBigEndian)

'  Send the file data (sends the entire contents of bdToSend).
success = sndSock.SendBd(bdToSend, 0, 0)

'  Get an acknowledgement.
success = sndSock.ReceiveInt32(bBigEndian)
If success = False Then
    Log(sndSock.LastErrorText)
    Return
End If


'  Did the receiver get the correct number of bytes?
If sndSock.ReceivedInt <> numBytes Then
    Log("The receiver did not acknowledge with the correct number of bytes.")
    Return
End If


Log("File sent!")

'  ------------------------------------------------------------------------------------
'  The code below is for the receiving side (running on some other computer..)

Dim listenSock As ChilkatSocket
listenSock.Initialize("listenSock")

success = listenSock.BindAndListen(5555, 25)
If success = False Then
    Log(listenSock.LastErrorText)
    Return
End If


'  Get the next incoming connection
'  Wait a maximum of 20 seconds (20000 millisec)
Dim rcvSock As ChilkatSocket
rcvSock.Initialize("rcvSock")
success = listenSock.AcceptNext(20000, rcvSock)
If success = False Then
    Log(listenSock.LastErrorText)
    Return
End If


'  The sender will first send the big-endian integer for the number of bytes
'  that are forthcoming..
success = rcvSock.ReceiveInt32(bBigEndian)
If success <> True Then
    Log(rcvSock.LastErrorText)
    Return
End If


Dim numBytesComing As Int = rcvSock.ReceivedInt

'  Receive that many bytes..
Dim bdReceived As ChilkatBinData
bdReceived.Initialize
success = rcvSock.ReceiveBdN(numBytesComing, bdReceived)
If success <> True Then
    Log(rcvSock.LastErrorText)
    Return
End If


'  Acknowledge the sender by sending back the number of bytes we received.
success = rcvSock.SendInt32(bdReceived.NumBytes, bBigEndian)

'  Close the connection.
Dim maxWaitMs As Int = 20
rcvSock.Close(maxWaitMs)

'  Save the received data to a file.
success = bdReceived.WriteFile("somePath/someFile.dat")
'  Assume success for the example...

Log("File received!")