Semantic Linkbacks
Semantic Linkbacks was a WordPress plugin that upgraded the presentation of linkback notifications; this plugin was deprecated 2023-04-04 and the functionality is now part of the WordPress Webmention Plugin.
Semantic Linkbacks upgraded the presentation of linkback notifications (like Trackback, Pingback, or Webmention*) from the ugly default pingback presentation of "[…] random text excerpt […]" to a much more meaningful and user-friendly display as comments, reposts, likes, and favorites, detected using microformats2 markup from the source of the linkback.
For explicit in-reply-to interactions, the plugin also changes the WordPress comment type from "webmention" to "comment". Otherwise, it creates human readable whole sentences like "Alice liked this article on alice.example.com." with hyperlinks to the source author and permalink.
- WordPress plugin directory: https://wordpress.org/plugins/semantic-linkbacks/
- GitHub Development Repository: https://github.com/pfefferle/wordpress-semantic-linkbacks
Comment Type Indicator
For in-reply-to interactions, the plugin adds a "type" indicator in the comment metadata for the specific type of interaction:
- reply
- repost
- like
- favorite
- rsvp
- tag
- listen
- watch
- read
- mention - Defaults to mention if another type cannot be determined, e.g. "Alice mentioned this article on alice.example.com."
This "type" indicator enables further interaction-specific presentation customization, such as showing likes/favorites and/or reposts as a facepile.
Configuration
- Automatically embed facepiles (may not work on all themes)
- Initial number of faces for facepile
Extensions
If you want to write your own parser for additional markup(such RDFa or Schema.org) you have to hook up the `semantic_linkbacks_commentdata` filter and update the array-fields.
The comment-array is a WordPress Comment with some extra-fields.
All fields beginning with _ like:
- `$commentdata['_canonical']` for the canonical source url
- `$commentdata['_type']` for the comment type. The plugin currently supports the following types: `mention`(default), `reply`, `repost`, `like`, `favorite`, 'tag', 'watch', 'read', 'listen', rsvp:yes, rsvp:no, rsvp:maybe, invited, rsvp:tracking.
- `$commentdata['_avatar']` for the author avatar
...are saved as comment metadata.
Replacement Brainstorming
Discussion between the author, 
Matthias Pfefferle and a contributor, 
One of the considered possibilities was switching from storing types of mentions from metadata to custom comment types. As WordPress does not officially support these(But also doesn't not support them), this would require more planning.
The plugin also does not store metadata in mf2_ prefixed Microformats, which is a convention that post dates it.
There is a separate thought that since multiple plugins parse Microformats 2 using the php mf2 library, but maintain separate code to turn this into a simplified structure for storage and display, that there might be a time saving benefit to using a common library developed outside the plugins for this.
Related Plugins
Webmention Plugin
*WordPress supports Pingback and Trackback by default; for Webmention support, you must install the separate Webmention Plugin which is very nicely complementary to the Semantic Linkbacks plugin.