}
        return crawlerContext.sessionId;
    }

    /**
     * Waits for the crawling process to terminate indefinitely.
     */
    public void awaitTermination() {
        awaitTermination(0);
    }

    /**
     * Waits for the crawling process to terminate for a specified duration.
     * @param millis The maximum time to wait in milliseconds. A value of 0 means wait indefinitely.
     */

        final String value = params.get(key);
        if (value == null) {
            return key;
        }
        return value;
    }

    /**
     * Thread to monitor and terminate processes that exceed the timeout.
     */
    protected static class MonitorThread extends Thread {
        private final Process process;

        private final long timeout;