static List<String[]> demanderPiece(String ip, int port, String question, int nbIteration, int tmpAttente, int taille_totale) throws UnknownServiceException, CharConversionException {    
	List<String[]> reponse = null;
	int tmp = 0;
	while (tmp < nbIteration){
	    try { 
		reponse = demanderPieceIntermediaire(ip, port, question, taille_totale);
		tmp = nbIteration*2; 
	    } catch (IOException ioe) { 
		tmp++; 
		if (tmpAttente>0)
		    try{Thread.sleep(tmpAttente);}
		    catch(InterruptedException ite){}				
		ioe.printStackTrace();
	    }
	}
	if (tmp <= nbIteration)
	    throw new UnknownServiceException(ip + "/" + port);
	
	return reponse;
    }