*/
    public Crawler() {
        crawlerContext = new CrawlerContext();
        final SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS", Locale.ENGLISH);
        crawlerContext.sessionId = sdf.format(new Date());
    }

    /**
     * Adds a URL to the crawling queue.
     * @param url The URL to add.
     */