resource_uri should support absolute URLs
It's often desirable to have absolute URLs returned so a client can simply request the value directly without having to add a protocol and hostname. This is easy to do in a custom read method but difficult to do with resource_uri.
The easiest solution would simply be to have an option for
resource_uri which would use
request.build_absolute_uri to generate a full URL from the resolver's response. This would prevent the use of alternate hostnames on complex sites, however, so it might be easier to pass in the request object and change the semantics slightly so a Handler's request_uri can return a string which will be returned directly.