Recently WouterJ has written an excellent article about repositories and how to treat them as collections. In it he also shows that it is useful to have interfaces on your repository classes. If you have not yet read it, I fully recommend doing so.
This concept is something I have recently applied in a project and found that there are some extra benefits in using those interfaces. In this post I would like to expand on WouterJ's ideas and show how this enables service decoration.