Missing parameter middleware for Restify (Node.js)

gistfile1.js

server.use((function () {
    var
        /**
         * Checks if a request parameter has been defined.
         */
        contains = function (parameter) {
            return this.params[parameter] !== undefined;
        },

        /**
         * Returns a request parameter if its defined otherwise 
         * throws a missing parameter error.
         */
        get = function (parameter) {
            if (this.contains(parameter)) {
                return this.params[parameter];
            } else {
                throw new restify.MissingParameterError(parameter +
                    " is required");
            }
        };

    /**
     * The middleware adds two new functions to the request object.
     */
    return function (req, res, next) {
        req.containsParameter = contains;
        req.getParameter = get;
        return next();
    };

}()));

sorry guys a stupid question: 'server.use()' define a common handler, wouldn't be more correct to use 'server.pre()' instead? Anyway in both cases i can't throw the MissingParameterError, i just get a 404 error, because the route without a parameter is not registered. i give you an example:

my route:
server.get('/list/:sessionId', listDevices);

if i try with "http://localhost/list" without the sessionId parameter i'd like to throw the MissingParameterError but your handler is not called.. and i get a 404.. i'm confused :-P

thank you guys