14.3. Example

Below are the codes of simple application server and client. Server waits for a connection from client, reads messages from client, and sends them back. Client connects to the server, reads data from keyboard, sends them to the server, and prints what server returns.

• Server source:

  // Stand for connection and simply make echo.
  #define DEFPORT  3000
  
  
  function main( cport )
  
  	local nPort, nH, nT := seconds() + 60
  	local nCon
  	clear screen
  
  	nport := iif( cport != nil, val(cport), DEFPORT )
  
  	if (nH := tcpListen( nport, 10 )) == -1
  		? "tcpsrv: Error listen on port ", nport
  		?
  		return( 1 )
  	endif
  
  	? "wait client connection"
  	do while( .t. )
  		if (nCon := tcpAccept( nH, 50 )) != -1
  			? "start",nH,nCon
  			start( @conEcho(), nCon )
  		endif
  		sleep(1)
  	enddo
  	tcpClose( nH )
  
  	?
  return( 0 )
  
  
  static function ConEcho( nH )
  // Make echo.
  
  	local cBuf := space(5), nL, cTxt
  
  	? "task, param : ", nH
  	do while( .t. )
  		if( (nL := tcpRead( nH, @cBuf, len(cBuf), 6000 )) > 0 )
  			if( nL == 1 .and. upper( substr(cbuf,1,1)) == "Q" )
  				exit
  			endif
  			? "tcpsrv, read : ", nL
  			cTxt := "tcpsrv:" + substr(cBuf, 1, nL)
  			tcpWrite( nH, cTxt )
  		endif
  	enddo
  	tcpClose( nH )
  
  return( 0 )

• Client source:

  #define BUFLEN   1024
  #define DEFPORT  3000
  #define DEFHOST "localhost"
  
  #define nTimeOut 600
  
  
  function main( cport, chost )
  
  	local nH, nPort , nL, cbuf := space( BUFLEN )
  	local nK, cEnv
  
  	clear screen
  
  	nPort := iif(valtype(cport)=='C', val( cport), DEFPORT )
  	if( chost == nil ); chost := DEFHOST; endif
  
  
  	? "Connecting to " + getHostByName( cHost )
  
  	if( (nH := tcpConnect( cHost, nPort, nTimeOut )) == -1 )
  		? "Error connecting to " + cHost + " on port "
  		?? nPort
  		?
  		return( 1 )
  	endif
  
  	nK := 0; cEnv := ""
  	do while ( nK != 27 )
  		if( (nL := tcpRead( nH, @cbuf, BUFLEN, 60 )) > 0 )
  			? "Received  ("+alltrim(str(nL))+"):"+substr(cbuf,1,nL)
  			?
  		endif
  		if( (nK := inkey( 0.1 )) == 0 )
  			loop; endif
  		if( nK == 13 )
  			nL := tcpWrite( nH, cEnv )
  			? "Send: ",nl, + cEnv
  			if upper(cEnv)=="Q"
  				exit
  			endif
  			cEnv := ""
  		else
  			cEnv += chr(nK)
  		endif
  
  	enddo
  
  	? tcpClose( nH )
  
  	?
  
  return( 0 )