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

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.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loBdToSend
LOCAL loSndSock
LOCAL lnBUseTls
LOCAL lnPort
LOCAL lnMaxWaitMs
LOCAL lnNumBytes
LOCAL lnBBigEndian
LOCAL loListenSock
LOCAL loRcvSock
LOCAL lnNumBytesComing
LOCAL loBdReceived
LOCAL lnMaxWaitMs

lnSuccess = 0

* 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.
loBdToSend = CreateObject('Chilkat.BinData')
lnSuccess = loBdToSend.LoadFile("somePath/someFile.dat")
* Assume success for the example...

loSndSock = CreateObject('Chilkat.Socket')
lnBUseTls = 1
lnPort = 5555
lnMaxWaitMs = 5000
lnSuccess = loSndSock.Connect("some_domain_or_ip.com",lnPort,lnBUseTls,lnMaxWaitMs)
* Assume success for the example...

* Tell the receiver how many bytes are coming.
lnNumBytes = loBdToSend.NumBytes
lnBBigEndian = 1
lnSuccess = loSndSock.SendInt32(lnNumBytes,lnBBigEndian)

* Send the file data (sends the entire contents of bdToSend).
lnSuccess = loSndSock.SendBd(loBdToSend,0,0)

* Get an acknowledgement.
lnSuccess = loSndSock.ReceiveInt32(lnBBigEndian)
IF (lnSuccess = 0) THEN
    ? loSndSock.LastErrorText
    RELEASE loBdToSend
    RELEASE loSndSock
    CANCEL
ENDIF

* Did the receiver get the correct number of bytes?
IF (loSndSock.ReceivedInt <> lnNumBytes) THEN
    ? "The receiver did not acknowledge with the correct number of bytes."
    RELEASE loBdToSend
    RELEASE loSndSock
    CANCEL
ENDIF

? "File sent!"

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

loListenSock = CreateObject('Chilkat.Socket')

lnSuccess = loListenSock.BindAndListen(5555,25)
IF (lnSuccess = 0) THEN
    ? loListenSock.LastErrorText
    RELEASE loBdToSend
    RELEASE loSndSock
    RELEASE loListenSock
    CANCEL
ENDIF

* Get the next incoming connection
* Wait a maximum of 20 seconds (20000 millisec)
loRcvSock = CreateObject('Chilkat.Socket')
lnSuccess = loListenSock.AcceptNext(20000,loRcvSock)
IF (lnSuccess = 0) THEN
    ? loListenSock.LastErrorText
    RELEASE loBdToSend
    RELEASE loSndSock
    RELEASE loListenSock
    RELEASE loRcvSock
    CANCEL
ENDIF

* The sender will first send the big-endian integer for the number of bytes
* that are forthcoming..
lnSuccess = loRcvSock.ReceiveInt32(lnBBigEndian)
IF (lnSuccess <> 1) THEN
    ? loRcvSock.LastErrorText
    RELEASE loBdToSend
    RELEASE loSndSock
    RELEASE loListenSock
    RELEASE loRcvSock
    CANCEL
ENDIF

lnNumBytesComing = loRcvSock.ReceivedInt

* Receive that many bytes..
loBdReceived = CreateObject('Chilkat.BinData')
lnSuccess = loRcvSock.ReceiveBdN(lnNumBytesComing,loBdReceived)
IF (lnSuccess <> 1) THEN
    ? loRcvSock.LastErrorText
    RELEASE loBdToSend
    RELEASE loSndSock
    RELEASE loListenSock
    RELEASE loRcvSock
    RELEASE loBdReceived
    CANCEL
ENDIF

* Acknowledge the sender by sending back the number of bytes we received.
lnSuccess = loRcvSock.SendInt32(loBdReceived.NumBytes,lnBBigEndian)

* Close the connection.
lnMaxWaitMs = 20
loRcvSock.Close(lnMaxWaitMs)

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

? "File received!"

RELEASE loBdToSend
RELEASE loSndSock
RELEASE loListenSock
RELEASE loRcvSock
RELEASE loBdReceived