An example in powerbasic
             
' Demonstrate multiple requests/responses within a single HTTP session
' (Requests are made sequentially)  
' Upload a file in XFER_CHUNK_SZ chunks
                                                                       
#COMPILE EXE "Upload.exe"                                      
                                                                                                                                                                    
#INCLUDE "WIN32API.INC"                                                                                                                                  
#INCLUDE "WinHTTP.inc"                                                              
#INCLUDE "WinHTTPWrap.inc"                                                            
                                                  
%XFER_CHUNK_SZ = 64000 ' 64k                                          
            
TYPE CHUNK_HEAD_TYPE 
    ChunkNum  AS DWORD '
    TotChunks AS DWORD '       
    DataLen   AS DWORD ' Payload Bytes  
    TotData   AS DWORD '
    sFileName AS STRING * 32 ' Shorten long filenames   
END TYPE 


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FUNCTION FileUpload( sPath AS STRING, sFileName AS STRING ) AS LONG      
                        
  LOCAL hSession, hConnect, hRequest AS DWORD
  LOCAL i, TotChunks, RetVal, hFile, LenHead, BytesRemain AS LONG
  LOCAL sAgent, sHost, sVerb, sData, sHeader, sBody, sResrc, sPOST AS STRING
  LOCAL pData AS BYTE PTR                                         
  LOCAL Head AS CHUNK_HEAD_TYPE ' Chunk variables Structure

            
 
    sAgent = "File Upload Example" '
    sHost  = "www.YourServer.com"
    sResrc = "/cgi-bin/FCGIUpload.exe" ' FastCGI application
    sVerb  = "POST"            
    Head.sFileName = sFileName
    LenHead = SIZEOF(CHUNK_HEAD_TYPE) ' length of prepended head
    '===========



    '- Read the File
    hFile = FREEFILE '
    OPEN sPath+sFileName FOR BINARY AS hFile ' Make a byte array with the contents of your file
      IF ERR THEN FUNCTION = -1 : EXIT FUNCTION
      Head.TotData = LOF(hFile) ' TotFileBytes
      IF Head.TotData = 0 THEN CLOSE hFile : FUNCTION = -2 : EXIT FUNCTION
      GET$ hFile, Head.TotData, sData ' read the whole file into a string    
    CLOSE hFile '
    pData = STRPTR(sData)
    FUNCTION = Head.TotData ' Default
    '=========== 
            

    DO          
        hSession = WinHTTPInitLib(sAgent, 0) '
        IF hSession < 1 THEN FUNCTION = -7 :  EXIT FUNCTION '                
        '===============  

        hConnect = WinHTTPConnectSrvr( hSession, sHost ) ' WinHttpConnect() 
        IF hConnect < 1 THEN FUNCTION = -15 : EXIT LOOP '
        '===============  

        Head.TotChunks    = Head.TotData\%XFER_CHUNK_SZ '
        IF Head.TotChunks * %XFER_CHUNK_SZ < Head.TotData THEN INCR Head.TotChunks ' One more for the remainder bytes
        IF Head.TotChunks = 0 THEN INCR Head.TotChunks '
        BytesRemain  = Head.TotData '
        '=============== 
                                  
        FOR i = 1 TO Head.TotChunks '
          hRequest = WinHTTPInitRequest( hConnect, sVerb, sResrc ) ' Create Request handle.
          IF hRequest < 1 THEN FUNCTION = -17 : EXIT FOR ' 

          Head.DataLen  = MIN(%XFER_CHUNK_SZ, BytesRemain)
          Head.ChunkNum = i

          '- Send POST Request
          RetVal = WinHttpSendRequestData( hRequest, 0, SIZEOF(Head)+Head.DataLen ) ' Prep Request
          IF RetVal < 0 THEN FUNCTION = -21 : EXIT FOR '                                              
                     
          RetVal = WinHTTPSendData( hRequest, VARPTR(Head), SIZEOF(Head)) ' Send the Header
          IF RetVal < 0 THEN FUNCTION = -22 : EXIT FOR '

          RetVal = WinHTTPSendData( hRequest, pData, Head.DataLen) ' Send the file
          IF RetVal < 0 THEN FUNCTION = -23 : EXIT FOR ' 
 
          pData = pData + Head.DataLen ' advance pointer to start of next chunk                            
          BytesRemain = BytesRemain - Head.DataLen ' decrement the bytes remaining            


          '- Receive the Response
          RetVal = WinHTTPGetResponse(hRequest) '           
          IF RetVal < 0 THEN FUNCTION  = -33 : EXIT FOR '                   
                     
          '- Read the Response Header HTTP Code
          RetVal = WinHTTPResponseHeaderInt( hRequest, %WINHTTP_QUERY_STATUS_CODE )
          IF RetVal = 0 THEN
            FUNCTION  = -34 : EXIT FOR
          ELSEIF RetVal > 299 THEN
            FUNCTION  = -35 : EXIT FOR
          END IF  

          '- Check the Response Body for an Error message
          RetVal = WinHTTPResponseBody( hRequest, sBody ) '
          IF RetVal < 0 THEN FUNCTION  = -37 : EXIT FOR '
          IF INSTR(sBody, "ERROR:") THEN FUNCTION  = -38 : EXIT FOR
                
          '- Close Request Handle
          IF hRequest THEN RetVal = WinHttpCloseHandle(hRequest)
          IF RetVal < 0 THEN FUNCTION  = -39 : EXIT FOR '
                     
        NEXT i
        '===============  

      EXIT LOOP
    LOOP '
 
    IF hConnect THEN RetVal = WinHttpCloseHandle(hConnect)
    IF RetVal < 0 THEN FUNCTION  = -40 : EXIT FUNCTION'
                                                    
    IF hSession THEN RetVal = WinHttpCloseHandle(hSession)
    IF RetVal < 0 THEN FUNCTION  = -41 : EXIT FUNCTION'

END FUNCTION 

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FUNCTION PBMAIN      
  
  LOCAL RetVal AS LONG       

    RetVal = FileUpload( "C:\Examples\HTTP\", "WinHTTP.gif" )
    IF RetVal < 0 THEN
      MSGBOX   "RetVal="+STR$(RetVal) + $CRLF + WinHTTPLastError,64,"Error"
    ELSE
      MSGBOX "All Done"
    END IF 

END FUNCTION 

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