On Monday, May 2, 2005, at 12:41 PM, Graham wrote:
http://www.intertwingly.net/wiki/pie/PaceDuplicateIDWithSource
Graham
=== Abstract
Allow multiple version of an entry within a feed where the source id is different.
Status
Proposed
Rationale
The current spec does not allow multiple versions of the same entry within a feed. In normal usage, this is OK, but when merging two feeds into a single feed, it requires duplicate detection and the discarding of data.
The abstract and rationale made me think this was proposing something entirely different from what it is--that multiple representations of the same entry resource could appear in a feed document as long as they were aggregated into the feed by different routes. What the actual proposed text allows is not multiple versions of the same entry, but multiple entries with the same id as long as they're from different feeds. When merging two feeds, duplicate detection will still have to be done, because both feeds could contain the same entry, with the same atom:source/atom:id.
Note it does not make legal having an entry without a source and a entry with a source, both of which have the same entry id, since the feed without a source may come from the same feed as the one with.
I don't see any reason to disallow this--the one without an atom:source would look to the current feed for its id. I don't see how this makes it any more likely that they'd come from the same feed. We could require that the feed have an atom:id in such a case if we want to, so that the IDs can be compared (ie. existing atom:id != missing atom:id is not good enough).
Proposal
In relation to atompub-format-08:
In section 4.1.1, replace:
atom:feed elements MUST NOT contain atom:entry elements with identical atom:id values
With:
atom:feed elements MUST NOT contain an atom:entry element that has the same atom:id value as any other atom:entry element, unless both atom:entry elements each contain an atom:source element, and the two atom:id values in each atom:source element are different.
Impacts
Allows duplicate ids within feeds, so atom:source must also be examined when looking for duplicates.
