Ring Middleware

Ring spec middleware flow:

     Request
        |
        V
------------------     --------------     --------------
| Authentication | --> |  Caching   | --> | Controller |
|   middleware   | <-- | middleware | <-- |   action   |
------------------     --------------     --------------
        |
        V
     Response

Example

var Rx           = require("rx");
var RxHttpServer = require("rx-http-server");

var preAction = function(next) {
    return function(data) {
        data.result = "[pre] ";
        return Rx.Observable.returnValue(data).flatMap(next);
    };
};

var postAction = function(next) {
    return function(data) {
        return next(data).map(function(n) {
            n.result += " [post]"
            return n;
        });
    };
};

var action = function(data) {
    data.result += "hello";
    return Rx.Observable.returnValue(data);
};

var server  = new RxHttpServer();
var handler = ringMiddleware(action, [
    preAction,
    postAction
]);

server.requests.flatMap(handler).subscribe(function(data) {
    data.response.writeHead(200, {"Content-Type": "text/plain"});
    data.response.end(data.result);
});

server.listen(3000);