I have a blog where users can post comments.

When creating a comment, various things happen:

• creating the comment object, associations, persisting
• sending notification emails to post's author given his preferences
• sending notification to moderators given their preferences
• updating a fulltext database for search
• ...

I could put all this in the controller, but what if I want to reuse this code ? e.g. I would like to provide an API for posting comments.

I could also put this in the model, but I wonder if I won't lose flexibility by doing so. And would it be acceptable to do all of this from the model layer ?

What would you do ?