Professional Ruby on Rails™

B.5. Merb

Merb (http://merb.rubyforge.org) is a Ruby web application tool designed to be very lightweight and have a tight integration with Mongrel. A Merb application has a slightly different structure than Rails — it's designed to allow easier partitioning of a project into deployable and non-deployable sections. Merb uses Erubis to define output views and, unlike Rails, allows for multiple render points in a single controller action. Merb allows for RESTful controller definitions.

Merb is specifically designed to hold on to a Mongrel process for less time than a Rails request would, allowing for a much faster web application. For example, Merb allows multiple files to be uploaded to the server at once. Also, Merb allows a controller action to return a block, which can be rendered by Mongrel in a separate thread for output processing.