A system comprising an application design server (120, 230), a first host device (110, 220) and a second host device (130, 240): wherein the application design server (120, 230) comprises: a communicator (121, 231); and a controller (122, 233) configured to control the communicator (121, 231) to: receive design data from the first host device (110, 220) and to store the design data in the application design server; in response to receiving (S620, S714) a request for the design data from a second host device (130, 240), transmit (S630, S715) the received design data to the second host device (130, 240); in response to receiving update information including identification information of the design data and information regarding items to be modified in the design data from the second host device (130, 240), transmit the update information to the first host device (110, 220) based on the identification information; and in response to receiving (S640, S719) updated design data which is generated by applying the update information to the design data from the first host device (110, 220), transmit (S640, S719) the updated design data to the second host device (130, 240); wherein the first host device (110, 220) is configured to: generate the design data; and generate updated design data by applying the update information to the design data; and wherein the second host device (130, 240) is configured to: generate an application; and generate a new application by applying the updated design data to the application. wherein the application design server (120, 230) comprises: a communicator (121, 231); and a controller (122, 233) configured to control the communicator (121, 231) to: receive design data from the first host device (110, 220) and to store the design data in the application design server; in response to receiving (S620, S714) a request for the design data from a second host device (130, 240), transmit (S630, S715) the received design data to the second host device (130, 240); in response to receiving update information including identification information of the design data and information regarding items to be modified in the design data from the second host device (130, 240), transmit the update information to the first host device (110, 220) based on the identification information; and in response to receiving (S640, S719) updated design data which is generated by applying the update information to the design data from the first host device (110, 220), transmit (S640, S719) the updated design data to the second host device (130, 240); a communicator (121, 231); and a controller (122, 233) configured to control the communicator (121, 231) to: receive design data from the first host device (110, 220) and to store the design data in the application design server; in response to receiving (S620, S714) a request for the design data from a second host device (130, 240), transmit (S630, S715) the received design data to the second host device (130, 240); in response to receiving update information including identification information of the design data and information regarding items to be modified in the design data from the second host device (130, 240), transmit the update information to the first host device (110, 220) based on the identification information; and in response to receiving (S640, S719) updated design data which is generated by applying the update information to the design data from the first host device (110, 220), transmit (S640, S719) the updated receive design data from the first host device (110, 220) and to store the design data in the application design server; in response to receiving (S620, S714) a request for the design data from a second host device (130, 240), transmit (S630, S715) the received design data to the second host device (130, 240); in response to receiving update information including identification information of the design data and information regarding items to be modified in the design data from the second host device (130, 240), transmit the update information to the first host device (110, 220) based on the identification information; and in response to receiving (S640, S719) updated design data which is generated by applying the update information to the design data from the first host device (110, 220), transmit (S640, S719) the updated design data to the second host device (130, 240); wherein the first host device (110, 220) is configured to: generate the design data; and generate updated design data by applying the update information to the design data; and generate the design data; and generate updated design data by applying the update information to the design data; and wherein the second host device (130, 240) is configured to: generate an application; and generate a new application by applying the updated design data to the application. generate an application; and generate a new application by applying the updated design data to the application.