- Predecessor of server-side JavaScript, long time before node.js was born, you could do server side things in JS with Apache Cocoon(Flowscript is part of Cocoon since 2004 at least).

- Best template engine ever: XSLT/XPath (whatever templating system you are using in your app, it will always abe subpar to XSLT/XPath), thanks to XSLTC(XSLT to byte code compiler) it's also the fastest templating engine you can have

- Pipelines and built-in caching system

- Sitemap

- MVC

Those are features I love about Cocoon, I guess for someone else other features will be more valuable.

Yet I'm unable to find any reason why Apache Cocoon is not so popular as it should be.. ?