* @throws CrawlerSystemException if data deserialization fails
     */
    public Map<String, Object> processRequest(final CrawlingConfig crawlingConfig, final String crawlingInfoId, final String url) {
        if (StringUtil.isBlank(crawlingInfoId)) {
            throw new CrawlingAccessException("sessionId is null. Cannot access document without a valid session ID.");
        }

    /** Session identifier key. */
    public static final String SESSION_ID = "sessionId";

    /** Crawling information identifier key. */
    public static final String CRAWLING_INFO_ID = "crawlingInfoId";

    /** Indexing target identifier key. */
    public static final String INDEXING_TARGET = "indexingTarget";

    /** Number of threads configuration key. */