docs: function authenticate(req, res, next) {
    var username = req.body.username,
        password = req.body.password;
  
    if (req.session && req.session.user.username === username) {
      // This user is already logged in
      next();
      return;
    }
  
    // Get the employee REST resource - /employees/{username}
    var dataStore = req.app.dataStore;
    var resource = new swagger.Resource('/employees', username, null);
    dataStore.get(resource, function(err, resource) {
      // Check the login credentials
      if (resource && resource.data.password === password) {
        // Login is valid, so create a new session object
        var sessionId = Math.random().toString(36).substr(2);
        req.session = {
          id: sessionId,
          created: new Date(),
          user: resource.data
        };
  
        // Save the session REST resource
        resource = new swagger.Resource('/sessions', req.session.id, req.session);
        dataStore.save(resource, next);
      }
      else {
        // Login failed
        res.sendStatus(401);
      }
    });
  }