A couple years ago I stopped using WordPress and switched to Octopress, which is a derivative of Jekyll. I continue to be pretty happy with this decision, but there are some downsides to using a static site generator. One issue is the lack of support for Pingbacks, which are a method supported by a number of dynamic blogging platforms to notify another blog when you link to its content. Pingbacks provide a good way to respond to blog posts using your own blog rather than via commenting; thus, they facilitate "conversation" between blogs. Unfortunately, if you're using Octopress or Jekyll or another framework to generate static HTML pages, you won't natively have the ability to send or receive Pingbacks.

Luckily, Pingbacks can be sent manually with relative ease. Receiving Pingbacks still won't be possible, though; that's a much harder problem to solve, for a variety of reasons which aren't relevant to this post.

Before I proceed, I want to note that full credit for this information goes to Aaron Parecki; he explains the technique in this GitHub Gist. The reason I'm reproducing it here is because it was surprisingly hard to find Aaron's Gist, or anything else of relevance, when I was searching for information on how to send a Pingback. Hopefully, by posting about it and adding some extra context, I can make the information more searchable.

First, you'll need to create a copy of this XML file on your local machine:

<?xml version="1.0" encoding="iso-8859-1"?>
<methodCall>
<methodName>pingback.ping</methodName>
<params>
 <param>
  <value>
   <string>http://source/url/here</string>
  </value>
 </param>
 <param>
  <value>
   <string>http://target/url/here</string>
  </value>
 </param>
</params>
</methodCall>

Replace the two URLs as appropriate - the first one is the source (i.e. your blog post), and the second is the target (the post you are linking to).

Now, you just need to POST the request to the target server. You'll need to know the target's XML-RPC endpoint URL for this. Usually, it will be /xmlrpc, or for WordPress blogs, /xmlrpc.php. You can find out for sure by inspecting the site's source for a <link rel="pingback" href="..."/> tag.

You can use cURL to post your request. It's built into most Unix-like operating systems, but Windows users will have to download it, and if you're on Mac OS X you probably need to have Apple's developer tools installed. Just run:

curl -X POST -d @pingback.xml http://example.com/xmlrpc.php

...and that's it! cURL should print out an XML response from this server with a message indicating that your Pingback was registered. Of course, to be truly sure it worked, you should check the target URL and see if your Pingback was added to the page. (Note that some sites disable Pingbacks.)