A system broadcast alarm messages from a server to a list of users among a plurality of multi-platform users sharing the server in a data transmission network which operates under Internet Protocol (IP) and uses the Java language. The system comprises a profile table containing the profiles of each user, a processing unit and a message sender enabling an administrator associated with the server to transmit alarm messages to the users of the list wherein the users have been selected by selecting profiles in the profile table. The alarm messages are displayed on the screen of the workstation associated with each selected user if this workstation is running.