Optional arguments for a REST web service?

Can one use optional arguments for a REST web service?  Example:

http://somesite/rest/someservice/{year}/ or http://somesite/rest/someservice/{year}/{cataglognumber}

where

The first uri returns all the catalog items given a year and

The second uri only returns the information given a year and a specific catalog number

How may I go about doing that?  Thanks in advance