Add webmention client code to Junco

Access these tags and links:

• #webmention
• #indieweb
• IndieWebCamp principles for building the indie Web
• http://webmention.org
• http://indiewebcamp.com/webmention
• https://github.com/phpish/webmention

"The ability for one webpage to let another know the first has linked to the second is a vital indieweb building block.
The key mention technology for the indieweb is: webmention"

http://gist.github.com/adactio/6575229 - "The form I put at the end of every blog post I make so that you can ping my webmention endpoint with your response."

<form method="post" action="/webmention.php">
<p>Have you published a response to this?
<label for="webmention-source">Let me know the <abbr title="Uniform Resource Locator">URL</abbr></label>:
</p>
<input type="url" name="source" id="webmention-source">
<input type="hidden" name="target" value="http://adactio.com/journal/6495/">
<input type="submit" value="Ping!">
</form>

Sep 15, 2013 - Parsing webmentions

Understanding

I'm still trying to understand webmentions and pingbacks.

I guess that I viewed this more as a remote-commenting function.

• Blogger A creates a post
• Blogger B would like to "comment" on Blogger A's post, but A does not allow comments.
• Blogger B can create a post that is responding to A, but unless B contacts A through e-mail or some other means, A will be unaware of B's blog response.
• But if Blogger A supported some kind of remote commenting system, and maybe that could be webmention, then Blogger B could create a blog post and include the URL to Blogger A's post.
• at the bottom of Blogger A's post would be Blogger B's blog post response title, which would be a link to Blogger B's reply post.
• Blogger B can only create one blog post response for each blog post by A.

The above would work and display similar to my reply as a blog post function in my Kestrel code that was removed when I started over with the Junco codebase.

Maybe a remote comment procedure would send to the original blog post app:

• reply blog post URL
• reply blog post title
• reply blog post author name/username that links to Blogger B's home page
• reply blog post creation/published date (date sent to Blogger A)
• an optional brief description or intro to the blog post, limited to x-number words or characters (Blogger A's software could set the char or word limit or not display the description at all)

Make it a POST request from Blogger B to Blogger A, and encapsulate the above info in JSON.

Could still be abused by spammers and trolls, unless Blogger A establishes a white list of users permitted to create blog replies. Blogger B would have to seek permission from Blogger A to be on the whitelist.

Webmention Protocol Summary

From http://indiewebcamp.com/webmention

Assuming Aaron's blog supports receiving webmentions, and Barnaby's blog supports sending webmentions:

1. User Aaron posts a blog post on his blog
2. User Barnaby writes post on his blog that links to Aaron's post.
3. After publishing the post (i.e. it has a URL), Barnaby's server notices this link as part of the publishing process
4. Barnaby's server does webmention discovery on Aaron's post to find its webmention endpoint (if not found, process stops)
5. Barnaby's server sends a webmention to Aaron's post's webmention endpoint with
   source set to Barnaby's post's permalink
   target set to Aaron's post's permalink.
6. Aaron's server receives the webmention
7. Aaron's server verifies that target (after following redirects) in the webmention is a valid permalink on Aaron's blog (if not, processing stops)
8. Aaron's server verifies that the source (when retrieved, after following redirects) in the webmention contains a hyperlink to the target (if not, processing stops)

Unmentioned but implied (and vaguely mentioned in the pingback spec):

• Aaron's server displays the information about Barnaby's post somewhere on Aaron's post.

#todo
#junco