Webmentions [1].
How hard could it be?
It's relatively straightforward, or so I thought until I started going down this particular rabbit hole yesterday [2]. The first stumbling block is sending a webmention. The protocol itself isn't that tough—just send a POST to an endpoint with the URL (Uniform Resource Locator) of my post, and the URL of the post I mentioned and that's pretty much it. But the issue I have is that I tend to link freely. This one paragraph post [3] has six links in it! When I exclude links back to my own blog, there are still three external links. Do I check each one? There are plenty of posts (like this one [4]) where sending a webmention isn't something I want to do. So I'm having a bit of analysis paralysis [5] on how exactly I want to handle this. For now, it's a manual process.
The second issue is one of handling incoming webmentions. I get the incoming request, I make a bunch of checks, then I have to actually fetch a web page and therein lies the hook—HTTP (HyperText Transfer Protocol) [6] is rather involved these days, what with three separate and largely incompatible versions and TLS (Transport Layer Security) to contend with and … well, I have some stuff I need to update before I can do all that. So for now, my webmention endpoint will just accept requests and email me the information. Maybe if I see just how much this is used in the wild will inform me of how much work would be involved. I don't know.
[1] https://www.w3.org/TR/webmention/#respecHeader
[2] https://www.flutterby.com/archives/comments/29860.html
[5] https://en.wikipedia.org/wiki/Analysis_paralysis
[6] https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol