Building a Web Crawler Using Elixir's Broadway and Wallaby

The article provides a comprehensive guide on creating a web crawler in Elixir using the Broadway and Wallaby libraries. It starts by discussing the limitations of conventional tools for web scraping and presents Broadway for managing concurrency and Wallaby for processing JavaScript-heavy websites. The author reviews previous works on custom Broadway producers and outlines the architecture of the crawler, which involves components like the URLQueue, URLProducer, Crawlers, and URLRegistry. Each site to be crawled will have its own Crawler responsible for processing pages and gathering links. The article dives into the implementation details, highlighting the importance of managing Wallaby sessions and ensuring the crawler is polite to avoid overloading servers. The article concludes by noting potential improvements and best practices for building efficient crawlers.