Dave Copeland:

We’ve given up on “fat models, skinny controllers” as a design style for our Rails apps—in fact we abandoned it before we started. Instead, we factor our code into special-purpose classes, commonly called service objects. We’ve thrashed on exactly how these classes should be written, so this post is going to outline what I think is the most successful way to create a service object.

Some good advice for building service objects in Rails.