define nginx::website(.....) {
}


class nginx::service{
  service{"nginx":...}
}


class webserver {
    case $httptype {
        nginx:  { include nginx }
        apache:  { include apache}
    }
}

define website(.....) {
   case $httpdtype {
      nginx:  { 
                 nginx::website{$name: .... }
              }
   }
}



node foo {
   $htpdtype = "nginx"

    include webserver
    website{"foo.com": }
}