You shouldn't ever request ids from a server, you should request id -- as a single item -- or a collection defined by the server and named (such as user/friends.json, not users?id=for,bar,baz,foobar).
Basically rest apis map exactly one resource to a url and should never use the hack that is ?.
That is simply not true. Can you provide me with some sort of citation on this? Fielding doesn't talk about URL construction in his thesis, and, in fact, specifically mentions things like collections and multiple entities residing in one resource.
Also, ? is not a 'hack', I don't know where you're getting that from either.
I used URL Templates (RFC 6570 - http://tools.ietf.org/html/rfc6570) so that the request to the server is not ad-hoc, but instead fully described by the resource body.
Basically rest apis map exactly one resource to a url and should never use the hack that is ?.