Over the last few years, as the smartphone has become more popular, we’ve moved from being excited about notifications to being worried about notification overload. Companies are hoping to get more data on us so they can tailor their interactions with us. We install analytics on our websites to determine how many visitors we get and what they did on our sites. At its simplest level, a linkback is a way of having a site(the sender) notify another site(the receiver) when it links to it. It sounds like something we would want to know and would have many potential uses.

WordPress has two built in linkback protocols: Trackback and Pingback. To many users, they seem like the appendix of WordPress. People don’t care about them until they are exploited by bad actors. There is a newer protocol, the first linkback protocol to be accepted as a draft specification from the W3C, the main standards organization for the Internet, called Webmention.

Webmention improves upon the previous protocols. It uses an HTTP POST request to send two parameters…the source and target URL. By comparison, trackback, which also uses HTTP, only sends the source URL and does nothing in its WordPress form to verify the trackback is legitimate. Pingback, like webmention, sends both source and target, but it uses XML-RPC as opposed to a POST request. XML-RPC has had some controversy around it as well. There are also several practices that are recommended by the Webmention specification that would make an implementation more robust than the implementations of Trackback and Pingback.

WordPress has a longstanding reputation of commitment to backward compatibility and isn’t going to flick the switch and remove pingback and trackback code from WordPress Core so easily, with or without a replacement.  It makes sense to make improvements to the older protocols concurrently with adopting webmentions, although it would also be a good idea to consider gradually deprecate the older protocols in favor of webmentions. Trackbacks have no source validation built into WordPress as it was not part of the original specification. The pingback code could use some love. However, with some refactoring, new webmention code could be used to update the older pingback/trackback code as well. This would create a better linkback system overall.

Even if webmention is a better delivery system for linkbacks than its predecessors, no one but a developer cares about protocols. People care about what it can do for you. All of the protocols converge in one place. Once you know a site has linked to you, what do you do with that information? That is where the exciting parts come in and where WordPress falls flat.

If one person would like to speak up in favor of the presentation of […]Useless Context. […], I’d love to hear it. The burden of presentation and use in a linkback relationship goes to the receiver and can be infinitely extensible. What WordPress lacks is a good base presentation for people to enhance and some innovative examples from the community of usage. If you can parse a page of HTML, you can come up with richer content and relationships by marking up the elements of a post with Microformats. WordPress already has some microformats embedded in most WordPress sites and supporting in many themes, and there are other efforts that can be made to better improve this side of things. But there are limitless possibilities, for example:

• Want to reply to a post on WP Tavern on your own site? Send a webmention(or more archaic protocol) to WP Tavern with the URL of your reply. WP Tavern could parse your site and generates an actual comment from it.
• Why only a reply? What about other types of relationships? Liking a post, for example?
• Even just simple administrator stats can be interesting and useful.

So, why not do all of this with an API? We have a new one coming into WordPress…and that’s a great thing I’m fully in favor of. But reading content from a website using an API creates a burden on both sides of the relationship. I have to write an API and you have to learn how to use it if you want to interface with my site. Why shouldn’t your website be your API?

If you are interested in trying webmention support, there is a basic plugin for WordPress. There is even a second plugin that uses Microformats2 plus linkbacks to generate richer comments. Both of these can be used to develop the more robust implementation that would be required for WordPress Core. For more information on how people have been using webmentions, visit IndieWebCamp.