Anne van Kesteren: Sam catches that referrer, does some magic, and displays an excerpt of the post in his comments, along with a link and the title of the post that linked him. I believe he uses the feed that is linked from the referrer’s post for that. (Yes, I’m jealous and like this feature.)
Anne, If you have any questions, feel free to leave a comment here, and I’ll try to answer them. As to the referers “magic”, here’s an outline:
- Twice an hour, I scan my referers since the last scan. I also use the Technorati API to identify additional referers.
- For each unique referer, I fetch the page and look for autodiscovery links (max one per page)
- For each feed, I scan for entries with a content that links to one of my entries
- For each such entry, I grab the summary, link, and title.
- If no such link already exists from my referenced weblog entry to that refering link, I sanitize and truncate the summary and post it as a comment.
I do support a number of different versions of RSS, which essentially amounts to a number of different synonyms for the xml elements (example: description, content:encoded, xhtml:body). Those with only one such element gets that element treated as if it were both the summary and content.
People without autodiscovery don’t get linkbacks. People with not-well-formed feeds don’t get linkbacks. People with summary feeds or who strip out all html don’t get linkbacks.
The code is here. I also support pingback, and trackback is integrated with my comments. On my todo list is revisiting my email logic to reject more of the lame spammers.