public void open() {
        filename = (String) params.get("output");
        boolean append = false;
        if (this.params.containsKey("mode")) {
            String mode=(String)this.params.get("mode");
            if (mode.equals("append")) {
                append = true;
            }
        }

        try {
            logger.debug("opening file destination to file '"+filename+"'");
            w = new BufferedOutputStream(new FileOutputStream(filename, append));
        } catch (Exception e) {
        //FIXME
        }
    }