Graham wrote:
>>"Does anyone remember why having the same id in a feed is a bad idea?"
> Beacuse instead of a fixed model where a feed is a stream of
> entries each with their own id, it is now a stream of entries each
> of which does not have its own id, but shares it with similar
> entries. This is bullshit.
I completely disagree on this.
I think the problem here is people focusing too much on
characteristics of the feed when the real issue here is Entries. Like I've
said in the past, "It's about the Entries, Stupid!" (don't take offense...)
As long as we allow entries to be updated, it is inevitable that the
stream of entries that is created over time will contain instances of
entries that share common atom:id values.
The only question here is whether or not we're willing to allow a
feed document to *accurately* represent the stream of entries -- as they
were created -- or whether we insist that the feed document "censor" the
history of the stream by removing old instances of updated entries before
allowing updates to be inserted.
The reality is that no matter which decision we make in this case,
any useful aggregator must have code to deal with multiple instances of an
entries that share the same atom:id. This is the case since even if we don't
permit duplicate IDs in a single instance of a feed document, we would still
permit duplicate ID's *over time." Because duplicate ids appear, over time,
whenever you update an entry, the aggregator has to have all the logic
needed to handle them in the *stream* of entries that it reads -- over time.
This issue only becomes interesting if we try to provide special
rules for the handling of data within a single instance of a feed document.
The reality is, however, that any aggregator that actually pays attention to
these special case rules is going to either get more complex (since it can't
simply treat everything as a stream of entries) or it will get confused
(since folk will intentionally or unintentionally create duplicate ids).
This ban on duplicate ids provides no benefit for aggregators, it
makes feed producers more complex, it tempts aggregator or client writers to
do dangerous things, it forces deletion of data that is useful to some
people for some applications, it puts too much emphasis on "feeds" when we
should be working on "entries", etc... It is a really bad thing to do.
bob wyman
