COMPOSITE SOFTWARE SYSTEM AND METHOD OF WRITING IT

The components (1L) of a composite software system communicate using "external" messages. They execute operations instigated by the reception of such messages and leading to the sending of other such messages. Each component comprises a plurality of communication ports which communicate separately with the environment external to the component to receive and send external messages and which also exchange internal messages with a kernel (1N) of the component to have the kernel carry out at least some or some parts of these operations. A specific application is to implementing the software of a telecommunication network central office.