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by AdieuToLogic 3382 days ago
URN's[0] can support resource categorization so long as the Namespace Identifier (NID) does not collide with the reserved ones (and I'd throw in those which are well-known in the industry as well).

So, for example, a URN which uses UUID's to satisfy uniqueness yet still allows for categorization could look like:

  urn:some-company:resource-type:abcdef012-3456-...
For complete technical conformance, the "some-company" NID would need to be requested/registered from the IETF.

In practice, my opinion is that the registration step is largely not required if the URN's are used strictly as an implementation detail within a system. However, those publicized and/or having a reasonable chance of being persisted by an external actor should have a sufficiently unique NID such that it can be registered and, more importantly, does not have a coincidental collision with other systems generating URN's.

0 - https://tools.ietf.org/html/rfc2648
2 comments
bpicolo 3381 days ago
Imo, this is a great combination of strategies when you want to keep people away from iterating. It also gives you the basis for a decent ACL system. Yeah, you use a few more bytes per item, but modern DBs can handle that.

Probably worth having a autoincrementing ID on tables using uuids as well, though. Not 100% sure on that, but I've definitely hit batch jobs that need to run / frameworks that require autoincrementing integer IDs, and getting stuck is a pain. (Adding an autoincrementing key after the fact is doable, but at least on postgres involves a rewrite the the entire table, so you kill the heck out of replication)

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AdieuToLogic 3380 days ago 

  Probably worth having a autoincrementing ID
  on tables using uuids as well, though.
Quite true, IMHO. I usually define both an auto-incrementing integral primary key (PK) as well as a unique string column for the URN. The PK is used for deletes/updates/joins/referential integrity and is never exposed beyond the server processes.
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jamiethompson 3377 days ago
How would one best use such URNs in a REST API?

An endpoint such as /products/:product-id:

Would be something like?

/products/some-company:products:abcdef012-3456...

Seems a little clunky

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