Re: One reason we have duplicates entries is that we have duplicate feeds...

[Tim Bray <Tim.Bray@xxxxxxx>]

On Apr 7, 2005, at 10:34 AM, Bob Wyman wrote:

> 	Tim suggests that aggregators should be able to rely simply on
> atom:id to detect duplicates. However, as has often been pointed out,
> applying this rule in an intermediary like PubSub would simply make 
> PubSub a
> marvelously efficient tool for denial of service attacks. I.e. if I 
> didn't
> like something you published, I would simply publish something in my 
> blog
> that had the same atom:id as something you had published. PubSub and 
> other
> synthetic feed producers would then flush your post from the system and
> replace it with my post... Not good -- and not avoidable given the 
> current
> loose rules for defining instances of atom:id.

Yes.  Mea culpa; somehow I'd missed this.  Would the following work:

1. A new feed-level element <atom:alt-uri-prefix>, any number allowed.  
E.g.

<feed>
  <link>http://www.tbray.org/ongoing/</link>
  <alt-uri-prefix>http://www.tbray.org/</alt-uri-prefix>
  <alt-uri-prefix>http://tbray.org/</alt-uri-prefix>
  <alt-uri-prefix>http://www.textuality.com</alt-uri-prefix

It says: an atom:entry can't be a duplicate of an atom:entry in this 
feed unless it comes from a feed whose URI begins with one of these.  
In conjunction with atom:id and atom:updated, it would solve most of 
PubSub's problem, but note that it only solves the problem for one 
level of aggregation.  Which I suspect is a useful 80/20 point.

By the way... bear in mind that virtually all duplicates are coming via 
things like Technorati and PubSub, so if we can figure out a fix, the 
number of players who need to implement it is small, and the motivation 
for them to do it is high. -Tim