[OSM-dev] API id placeholders
frederik at remote.org
Sun May 6 09:15:18 BST 2007
> Couldn't the OSM API be made to accept negative ID numbers as
> placeholders in this fashion, and to allow multiple objects (e.g.
> these two nodes and one line segment) in one request? Would that
> terribly break some rule in the REST bible?
> Sometimes when I need to change the direction of every line
> segment in a long way, or want to change or remove an attribute
> from a large number of objects
Both topics are not really related - your "update many objects at once"
request could be met even without the "negative numbers as placeholders"
The problem with both is return values. If you send a request that is
intended to update many objects at once, and one fails (e.g. because the
object you intend to update has been deleted in the mean time), then how
will you know which one failed? The API doesn't use or support
transactions, so it cannot roll back the database to whatever state it
was in before it started processing your multi-update. One would have to
devise a more complex return value indicating a position within the
request where the failure occurred.
With object creation failure situations are even more complex, but even
if everything goes well you (or your editor) needs to know which IDs
were actually assigned to each of the new objects, so the return value
would have to be some sort of mapping table "node -1 -> 1234567".
All not impossible, but not easy either. And, while there's no reason to
be fanatic about anything, the idea behind REST is usually to have calls
that work with one object and not with a collection.
Frederik Ramm ## eMail frederik at remote.org ## N49°00.09' E008°23.33'
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