Graham wrote:
>> [1] do you know of any publishing software which currently emits
>> feeds with multiple instances of entries? I can't think of any.
> None. That's why it should be explicitly barred, since no software
> is expecting it.
PubSub regularly produces feeds with multiple instances of the same
atom:id. No one has every complained about this to us.
Given that history shows that publishing repeated ids has never
bothered anyone enough to cause them to complain, we should permit this
benign practice to continue.
It is particularly important to avoid prohibiting this benign
practice since it is so important to generators of aggregated feeds.
Aggregated feed generators are supposed to maintain atom:id unchanged when
they copy entries into an aggregate feed. However, the Atom format doesn't
provide rigorous guarantees that atom:id's will be unique across feeds.
Thus, aggregated feed publishers are left with the choice of 1) Trusting
feed publishers or 2) Assigning new atom:id's to all entries published. The
first option will inevitably result in repeated ids and the second results
in massive amounts of work, difficulties in duplicate detection, violation
of the "maintain atom:id" rule, etc.
Forbidding repeated ids causes damage. History shows, however, that
allowing repeated ids is benign.
bob wyman
