I was very annoyed the last time I looked at this.
Webmentions are like trackbacks, but trackbacks that do not contain the information needed to show them, instead relying on the receiving party to fetch that information from a microformat (that part seems to be missing from the spec).
What annoyed me so much that I opted to not implement it in any of those blog engines I'm involved in is that it is a useless re-invention of trackbacks. There is no point in webmentions, not one feature that could not be done with trackbacks as well. They have a wikipage arguing against trackbacks on https://indiewebcamp.com/Trackback, and all points on that page are wrong when looking at how blog engines actually implement trackbacks. Just take the first, fragile discovery: The critic is that the RDF comment needed for Trackbacks is is complex and get stripped. But frankly, it is not complex to grep for it and if you can't control your own page HTML to preserve comments, you have different problems (and one that could hit your microformat equally). More important: Trackbacks actually can be found via a rel-tag in the site head exactly like pingbacks (and I guess webmentions), rel=trackback.
And of course blog engines verify that the origin really has a link to the receiving page, the spam problem is solved there exactly like with webmentions.
What should be done is to take trackbacks and formalize the current solutions and extensions into a formal protocol. There is no need to willfully cut out the existing independent web, as in blogs, for a hipster indieweb movement.
I use trackbacks, since my chosen blog engine (serendipity) supports them. I know a number of other bloggers and they all use trackbacks. My last non-spam trackback came in on Nov 9 2015, 08:02, ignoring the ones I sent to myself (I was not very active in the meantime).
Trackbacks are alive as well. But yes, they should be revisited and repackaged, I agree that they could need a popularity boost. But that is possible without breaking compatibility for no reason.
Being on top of pingbacks makes no sense, xml-rpc is dead and a bad idea in a first place, also a lot harder to implement than just reacting to a ping + pretty much incompatible with the pull concept. If they started there, they probably did not know trackbacks existed.
Webmentions are no simpler than trackbacks, and to have them diverge for no reason makes everything more complicated for the engine. It is no straight-forward simplification at all, thus no good thing.
Thanks for the link, I appreciate the idea. Sadly, this seems useless for me. I'd need a service that I can point to in the head that converts the webmention to a trackback (and not a pingback, though that would work as well if absolutely necessary, but by default pingbacks have no description which could collide in some themes; also a harder codepath) and then sends the trackback to the blog. Fetching that later with JS is no option, it has to end up in the database.
I hope I did not just miss that (now again and when I saw it the last time), but this does not seem to capable of that.
Hi there, I made webmention.io. I haven't updated the readme or home page yet, but I recently added a "web hook" feature which is similar to what you're talking about with Trackbacks. The service will receive and verify the webmention, parse the page, and then send a post request with the contents of the comment. The format it sends looks like this http://indiewebcamp.com/jf2#Example
So, it's not quite trackback, but hopefully it's more useful!
Nice, yes, that is similar. It would be a lot more useful for me to get a trackback though – to make the blog engine receive webmentions by just converting a webmention to a trackback by your or another service would be the easiest way possible.
And something I would push into our html markup and debug (the service in the middle might make some origin checks fail), despite my concerns with webmentions as a spec and concept.
The main reason Webmention is less susceptible to spam than Trackback is, is because with Trackback, there is no requirement that the comment text have its own URL. At least with Webmention, a spammer has to create a URL for the spam comment.
The webmention.io service sends a secret token in the payload so you can verify the request came from there.
That is what I kind of tackled above, I think: In practice, all blog engines will confirm that the URL the trackback points to actually contains a link to the site receiving the trackback. I see no practical difference there between the two protocols. But your use of comments and comment urls makes me think I might miss your point?
Thanks for opening the issue, I will add a comment and subscribe.
> The critic is that the RDF comment needed for Trackbacks is is complex and get stripped.
That is super valid and the main reason why I back then in 2004 didn't implement trackback in my bloging engine but only pingback. Semantics matter.
It is virtually never parsed as RDF. RDF-in-HTML-comments is a horrible antipattern that has no use in the RDF community outside of the weird legacy use case of Trackback.
It is hidden metadata (which can and does break) and violates the DRY principle.
It is as much hidden metadata as is any other of such attempts, like schema.org and what else exists. It is a not so beautiful repetition of stuff that is already in the html, true, but it stems from another way of thinking about metadata. Maybe the RDF community does not like it anymore, but it was a thing.
Note that I'm not fan of this, rel=trackback is what should be used. But it is not complicated to add those tags into a page, which was my point.
The DRY principle in its original form does not apply here: The information in those tags will change when the information in the database changes. They are not hardcoded.
Schema.org RDFa isn't hidden. JSON-LD in a script tag is but that's equivalently goofy.
"stems from another way of thinking about metadata"? Nope. It was a clumsy hack because they actually just wanted to put the <rdf:RDF> tags in the HTML but people would complain about HTML validation so they put it in a comment tag.
At least back then I found it mega complicated, I would have needed to screen the content of the page and find the comments most probably with a RegEx I guess? Then I would need to feed the comment strings I get into a XML parser which would understand namespaces. Then I would go through the DOM of every of those comments to get out the data.
Apart from that I do not think you should compare pingback/webmention with trackback. The ones are to inform about some mention/comment, the other is transporting the content of it. If you want to compare than I would compare microformats/open-graph with trackback.
You probably would not use an XML parser. All the information needed to send a trackback is the ping-location, that is one ugly regexpression, but only one. I also am no fan of that, rel=trackback is nicer. But the (pragmatic approach to) parsing is simpler than you describe.
I'm actually not okay about the distinction. Trackbacks inform and transport the content, and webmentions inform and are coupled with an unspecified convention to get the content. They end up having the same purpose.
Webmentions are like trackbacks, but trackbacks that do not contain the information needed to show them, instead relying on the receiving party to fetch that information from a microformat (that part seems to be missing from the spec).
What annoyed me so much that I opted to not implement it in any of those blog engines I'm involved in is that it is a useless re-invention of trackbacks. There is no point in webmentions, not one feature that could not be done with trackbacks as well. They have a wikipage arguing against trackbacks on https://indiewebcamp.com/Trackback, and all points on that page are wrong when looking at how blog engines actually implement trackbacks. Just take the first, fragile discovery: The critic is that the RDF comment needed for Trackbacks is is complex and get stripped. But frankly, it is not complex to grep for it and if you can't control your own page HTML to preserve comments, you have different problems (and one that could hit your microformat equally). More important: Trackbacks actually can be found via a rel-tag in the site head exactly like pingbacks (and I guess webmentions), rel=trackback.
And of course blog engines verify that the origin really has a link to the receiving page, the spam problem is solved there exactly like with webmentions.
What should be done is to take trackbacks and formalize the current solutions and extensions into a formal protocol. There is no need to willfully cut out the existing independent web, as in blogs, for a hipster indieweb movement.
I guess I'm still annoyed.