The present invention is a system for performing communication among a plurality of applications running on a portable terminal device, wherein the portable terminal device includes a token generation unit that generates a token; a publishing unit that sends a publish message including the token and a payload to the server, the publish message being a message to be sent from one app running on the portable terminal device to another app; and a subscription unit that sends a subscribe message including the token to the server, the subscribe message indicating that the other app can receive data sent from the publishing unit, and wherein the server, when the publish message is received, compares the token included in the publish message with the token included in the subscribe message, and sends the payload to the other app in the case where the result of the comparison satisfies a predetermined condition.