Optional arguments for a GET REST web service

Can one use optional argument for a GET REST service?  For example:

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

or

http://somesite/rest/someservice/{year}/{catalognumber}

In the first case, it returns all the catalog information given a year.  In the second case, it only returns information for a given year and catalognumber?

How may I proceed in accomplishing that?  Thanks in advance.