How to use the express.session function in express

// all environments
app.set('ipaddr', settings.application.ip);
app.set('port', process.env.PORT || settings.application.port);
if (process.env.PORT) {
  settings.application.port = process.env.PORT;
}
app.set('views', 'shared_views');
app.set('view engine', 'jade');
app.set('trust proxy', true);
app.enable("jsonp callback"); //TODO: Remove this if not needed because of CORS
app.use(express.favicon(path.join(__dirname, 'public/img/favicon.png')));
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(express.cookieParser('eobfgl-shoe'));
app.use(express.session());


//Set up a public folder.
app.use(require('less-middleware')({
  src: __dirname + '/public'
}));

//Items in these folders will be served statically.
app.use(express.static(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'GPModels')));

//support for storing authentication credentials
var passport = { authenticationFunctions: []};

//This must be after app.use(passport.initialize())
app.use(cors());

app.configure(function() {
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.set('view options', {layout: false});
  
  app.use(express.favicon())
  app.use(express.cookieParser());
  app.use(express.session({secret: settings.webserver.sessionKey}));
  app.use(function(req, res, next) {

    req.auth = {user: "webuser"};
    
// Used to implement authentication handled by a proxy upstream, by default assume "webuser" is always logged in.
/*
    if (req.headers["x-authenticated-user"]) {
      req.auth = {user: req.headers["x-authenticated-user"]};
    }
*/
    next();
  });
  
  // Force user to be logged-in for access
  app.use(function(req, res, next) {
    // Redirect user to proxy login page if not logged in

app.configure(function() {
  app.set('views', __dirname + '/views');
  app.set('view engine', 'ejs');
  app.use(express.logger());
  app.use(express.cookieParser());
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(express.session({ store: sessionStore, secret: 'keyboard cat' }));
  // Initialize Passport!  Also use passport.session() middleware, to support
  // persistent login sessions (recommended).
  app.use(flash());
  app.use(passport.initialize());
  app.use(passport.session());
  app.use(app.router);
  app.use(express.static(__dirname + '/../../public'));
});

var walk    = require('walk');
var spawn   = require('child_process').spawn;
var exec    = require('child_process').exec;
var _       = require('underscore');
// ------------------------------------------------
// BASIC USER AUTH w/ EXPRESS
// ------------------------------------------------
function authorize(user, pw) {
  var userIsOk = false;
  userIsOk |= (user === 'user' && pw === 'password');
  return userIsOk;
}
var app  = express.createServer();
app.use(express.bodyParser());
app.use(express.cookieParser());
app.use(express.session({ 
  secret: "a very secret secret",
  store:  new express.session.MemoryStore,  
  cookie: {  
    path     : '/',
    httpOnly : true,
    maxAge   : 1000*60*60*24*30*2    //60 days
  } 
}));
//app.use(express.basicAuth(authorize));
var uCount = (new Date()).getTime()%99999;
app.use(function(req, res, next){
  req.user = req.user || {};
  if(req.cookies && req.cookies["_username"]){
    req.user.displayName = req.cookies["_username"];
  }else{
    req.user.displayName = "user_"+(uCount++);

var mongo = require('mongodb');
var async = require('async');
var express = require('express');
var passport = require('passport');
var app = express.createServer();
var sanitize = require('validator').sanitize;
var RSS = require('rss');

app.use(canonicalizeHost);

// Use the body parser express middleware to automatically parse
// POST form submissions
app.use(express.bodyParser());
// Make cookies available for sessions, which Passport requires to give us logins
app.use(express.cookieParser());
app.use(express.session({ secret: options.sessionSecret }));
// Now we can configure passport
configurePassport();

// Serve static files (such as CSS and js) in this folder
app.use('/static', express.static(__dirname + '/static'));

// Underscore templates to render various pages
options.templates.post = _.template(fs.readFileSync(__dirname + '/templates/post._', 'utf8'));
options.templates.postBody = _.template(fs.readFileSync(__dirname + '/templates/postBody._', 'utf8'));
options.templates.layout = _.template(fs.readFileSync(__dirname + '/templates/layout._', 'utf8'));

var db;
var postCollection;

async.series([connect, listen], ready);

var go = function() {
	var app = express();

    app.set('views', __dirname + '/views');
    app.set('view engine', 'jade');

    app.use(express.logger('dev'));
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: true }));
    app.use(methodOverride());

    app.use(express.cookieParser());
    var sessionStore = new express.session.MemoryStore();
    app.use(express.session({ secret: 'windoge', store : sessionStore }));

    // Set the x-powered-by header
    app.use(function(req, res, next) {
        res.header("X-powered-by", "Hobu, Inc.");
        next();
    });

    app.use(require('less-middleware')(path.join(__dirname, 'public')));
    app.use(express.static(__dirname + '/public'));

    // development only
    if ('development' == app.get('env')) {
        app.use(express.errorHandler());
    }

    app.use(app.router);

app.configure(function() {
    app.use(express.cookieParser());
    app.use(express.session({ secret : 'keima' }));

    if(app.settings.env == 'development' || config.twitter.callback) {
        app.use(auth([
            auth.Twitter({consumerKey:    config.twitter.consumerKey,
                          consumerSecret: config.twitter.consumerSecret,
                          callback : config.twitter.callback || 'http://localhost:3001/auth/twitter_callback' })]));
    }else{
        app.use(auth([
            auth.Twitter({consumerKey:    config.twitter.consumerKey,
                          consumerSecret: config.twitter.consumerSecret})]))
    }
    app.set('views', __dirname + '/views');
    app.set('view engine', 'jade');
    app.use(express.bodyParser());

    // helper

};

exports.watch = function(obj, cb) {
	if(!watchers[obj.sid]) watchers[obj.sid] = {};
	if(Object.keys(watchers[obj.sid]).length > 4)
		return;
	watchers[obj.sid][obj.cid] = cb;
	console.log(watchers);
}

exports.unwatch = function(obj) {
	if(watchers[obj.sid] && watchers[obj.sid][obj.cid])
		delete watchers[obj.sid][obj.cid];
}

var exparse = express.session({
	secret: secret,
	key: key,
	store: store
});

exports.store = store;

var parse = exports.parser = function(req, res, next) {
	exparse(req, res, function() {
		if(!req.session.user) {
			req.session.user = initUser();
			req.session.cookie.value = 's:' + signature.sign(req.sessionID, secret);
			store.set(req.sessionID, req.session);
		}
		next();
	});

function Configuration(app){
	app.set('views', __dirname + '/views');
	app.set('view engine', 'jade');
	app.set('view options',{layout:false});
	app.use(express.bodyParser({uploadDir:rootdir+'/public/images/'}));
	app.use(express.cookieParser());
	app.use(express.session({secret:'keyboard cat',store:new RedisStore}));
	app.use(express.methodOverride());
	app.use(express['static'](__dirname + '/public'));
    app.use(express.favicon(__dirname+'/public/favicon.ico'),{
        maxAge:2592000000    
    });
	app.use(app.router);
}

app.configure(function(){
    app.use(express.cookieParser());
    app.use(express.session({ 'key':'codematics',secret: "BSAIDG&*A^yuguisayds8a7" }));
    app.use(express.bodyParser());
    app.use(express.static(__dirname + '/public'));
    app.use(setSession);
    app.use(app.router);
});