1. An information processing system including at least one terminal apparatus and at least one program execution apparatus, wherein each of said at least one terminal apparatus comprises a message transmitting unit which transmits a message containing version information indicating a program version; and each of said at least one program execution apparatus comprises, a message receiving unit which receives said message containing version information indicating a program version, from one of said at least one terminal apparatus, a program storing unit which stores one or more program components, a pre-transfer information management table which holds information on said one or more program components stored in said program storing unit, a program memory unit which is allocated to an activated process, and temporarily stores at least one program component transferred from said program storing unit, a post-transfer information management table which holds information on said at least one program component stored in said program memory unit, and a program executing unit which dynamically links one of said one or more program components corresponding to said version information contained in said message received by said message receiving unit, to said program memory unit, so as to enable execution of said one of said one or more program components in said process.