})
                .prototype("accessResult", AccessResultImpl.class)
                .prototype("urlQueue", UrlQueueImpl.class)
                .prototype("crawlerThread", CrawlerThread.class)
                .prototype("crawler", Crawler.class)
                .prototype("urlFilterService", UrlFilterServiceImpl.class)
                .prototype("urlQueueService", UrlQueueServiceImpl.class)

```

### Key Components

#### Core Engine
- **Crawler**: Main orchestrator managing crawl execution
- **CrawlerContext**: Execution context and configuration
- **CrawlerThread**: Individual crawler thread implementation

#### Client Architecture
- **HcHttpClient**: HTTP/HTTPS client using Apache HttpComponents
- **FileSystemClient**: File system access
- **FtpClient**: FTP protocol support