Crawler is a simple Web crawler (or spider). Its main goal is to abstract the boring and error-prone code from your codebase and let you focus on crawling the site. Also, it's quite easy to use.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.
