Question

I have a REST api that will accept a version via a custom HTTP header or a request parameter. I’m doing this because I don’t want the URI to contain the version like del.icio.us .e.g http://server/api/v1/…

Now in my design, the HTTP header has a higher priority than the request param.
What happens then if the user does not supply any version at all ?
Should I default to the oldest version, or default to the latest version ?

Answer 1

Don’t version the URI at all. Instead just version the representation. This way the client can decide which version of the API they want to use and it degrades well.

Example:

GET /contacts/3 HTTP/1.1
Accept: application/myapp-v2+xml

HTTP/1.1 200 OK
Content-Type: application/myapp-v2+xml