Abstract: The invention relates to a protocol for exchanging data between applications of a portable multi-application object, such as a microprocessor or smart card. An internal communications interface is implanted in the nonvolatile memory of the smart card. Given a message sending command and message reception command, a source application attribute (E-ID) is assigned a) to an application, and a target application attribute (R-ID) is assigned b) to at least one other application. The exchange of information messages (MSG) c) is done between source and target applications by means of the communications interface used as an intermediary. The invention is applicable to the management of portable multi-application objects, such as processor cards, PCMCIA cards, or the like.