How can a Facebook application notify a user of something?
The example is a website allowing users (who are associated with Facebook users) to create a blog post. The commenting system is the fb:comments social plugin.
When someone leaves a comment, the writer of the blog post should be notified that there is something new to read.
What I would expect as a writer is that I would get a notification (ie. "x has commented on your blog post."). There doesn't seem to be a way to generate those notifications though.
What methods are there in the Graph API for the writer to learn about the new comment? Which is the "best"?
Do one or both of the following:
Send App-to-User Requests. They won't generate notifications, but they will increment some app counters. Among other places, the user will see the counter at the top-right corner of her wall.
Use the email permission to get the user's e-mail address. Store the address on your server and send the user an email whenever she needs to be notified.