[RestExtension("myAlias")]
    public class Test
    {
        [RestExtensionMethod]
        public static string HelloWorld()
        {
            return "Hello world";
        }
        [RestExtensionMethod(allowAll=false , allowGroup="custom")]
        public static string AnotherWithPermissions()
        {
            return "Hello member in custom group";
        }

    }

http://umbraco.org

new in umbraco Juno, RestExtension and RestExtensionMethod attribute, no more need to update the restExtension.config file but simply mark type and methods...
(rest extensions are used for umbraco base)

Umbraco Juno, RestExtension and RestExtensionMethod attribute

C#