Does TreeGateway expect an external User service?

[sivabudh]

For example, if I'm using GoogleStrategy as follows:

var passport = require('passport');
var GoogleStrategy = require('passport-google-oauth').OAuthStrategy;

passport.use(new GoogleStrategy({
    consumerKey: GOOGLE_CONSUMER_KEY,
    consumerSecret: GOOGLE_CONSUMER_SECRET,
    callbackURL: "http://www.example.com/auth/google/callback"
  },
  function(token, tokenSecret, profile, done) {
      User.findOrCreate({ googleId: profile.id }, function (err, user) {
        return done(err, user);
      });
  }
));

Is the User model expected to be a separate (micro)service which TreeGateway will connect to? Since TreeGateway is an Express application, is there a canonical way to extend it?