Neil Turner's Blog

Blogging about technology and randomness since 2002

The Atom ID debate

Yesterday, Mark wrote an article about how to make a good ID in Atom. The entry ID is like a GUID in RSS – it’s a unique identifier that doesn’t change, even if the entry URL changes. For example, I could change the title of this entry to ‘cheese’, which would cause the URL to change – without the ID, many aggregators would think I’ve written a new entry when all I’ve done is alter the title.
When you have read that, read this from Tim Bray. He explains why Mark is wrong, what you should do instead, and also the wider problem (if the URLs can change then you’re probably using bad software).
The thing is, both Mark and Tim are right. IDs are there to solve a problem, but the IDs themselves are not an ideal solution. Still, they’re better than nothing, so if you’re reading this and wondering whether IDs are really necessary in Atom, then trust me, they are. In any case, they are required, so if you don’t include them your Atom feed will be invalid.

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