Especially not, if they're called “permalink” :)

I'm not talking about a reorganization of your site or a change of the blogging software and the sometimes inevitable change of uris after years or so (and it's most of the time avoidable nevertheless with some mod_rewrite magic), but changing them within a short time after an article was published…

Some blogging software generates the permalink automatically from the title, the date and evt. the category and create a new oneevery time you change the title for example due to a typo. Speaking urls are of course the way to go (see also the latest namics blog post about that subject, in German), but bad for aggregators like Planet PHP or Planet Ping. It leads to double posts…

There are mainly two solutions for the aggregator problem. The blogging software should use the element (in RSS 2) or the element (in Atom) with a really not changing id (for the last post on this blog it is for example “http://blog.bitflux.ch/archive/id/3128/”). The Planet PHP software does respect those elements and updates the entry accordingly instead of inserting a new one when the changed.

The second solution – and this also helps people, which already linked to your post – is not to change the permalink at all, even if you change the title. You may still have that typo in there, but others won't get annoying 404 pages.

Flux CMS does exactly this. It auto-generates a permalink for you (or better said, it makes a proposal on the fly, which you can change), but if you later change the title, it keeps the old URI. And you still can change it, if you really want to. And of course, it adds to the RSS 2.0 feed (which never changes, except if you delete the post and make a new one with the same title and content).

So, please dear blogging software vendors, add those features or add at least the or element and make those really unique and permanent. It makes life for aggregators a lot easier.