[wp-hackers] Ping and trackbacks.

[Michel Valdrighi]

On Tue, 25 Jan 2005 07:29:15 -0500, Scott Merrill <skippy at skippy.net> wrote:
> Pingbacks send only the ping, with no content.  Pingbacks are generally
> best thought of as "off-site comments", and the ping is intended to let
> the ping recipient know that the ping originator has something to say
> about the matter.

Pingbacks are only intended to say "I link to this content from this
content", nothing more nothing less. A linkblog with no commentary
would therefore use Pingbacks. Or one could send Pingbacks to each of
the links in their blogroll once, to notify that they're linked.


> Pingbacks were designed to overcome many of the deficiencies of
> trackbacks.  There's no verification of trackbacks: it's a one-way
> communuication from trackback originator to trackback recipient.

Pingbacks also do not suffer from the autodiscovery plague that
characterizes TrackBack. No need to insert RDF in HTML files, an HTTP
header is enough (or failing that, a <link /> tag). Since an HTTP
header is enough, Pingbacks are not limited to HTML/XML content. One
could pingback an image, for example, if the image is served with an
X-Pingback header (and the server supports it).


> Pingbacks are a two-way connection, in which the pingback recipient will
> actually make a new connection to the pingback originator to confirm
> that the ping is coming from a legitimate source.

Pingback servers MAY check for the pingback's legitimacy. This is
recommended but not necessary. It's just that the first
implementations did this, so it got into general usage.


> Pingbacks are harder to spoof (though not impossbile), and can therefore
> be considered as more "authoritative".

Sadly, they can be spoofed, they just require a synchrone way to
change a link on the sender's side. But that would be slow (you would
have to assume the receiver will take one to several seconds to check
your page), so it's not really profitable for spammers, far from being
as profitable as sending a boatload of HTTP POST requests is.


Anyway kudos for the wiki page.
I may edit it to provide some clarifications on the Pingback side
someday, but as it is now it is fine without them.

-- 
Michel Valdrighi
Devéloppeur Web Intraordinaire
http://intraordinaire.com/