Figure 4 shows the five main modules of the place recommender system in the form of class diagram. According to this figure, the system consists of five modules: APIFourSquare, login, Location, Recommender and Register.
1) APIFourSquare: This module functions to contact foursquare service to retrieve real-time information about venues via Foursquare API. Figure 5 gives an example of retrieving place information by sending a GPS location to Foursquare database.
2) Login: This module performs to authentication to allow only Foursquare activated users to log into system.
3) Recommender: This module performs to make a set of recommended places to the mobile phone user based on our collaborative filtering algorithm described in Section III.
4) Location: This module will handle the temporary results performed by the recommendation algorithm using MySQL database.
5) Register:This module handles non-registered users by allowing to create a foursquare account via the mobile application.