Dynamic software replacement model and its Ada implementation

It is not possible to develop software systems that do not need to b modified during their operational life. This process, which is known as maintenance, is the longest phasein the software life cycle, specially when dealing with long-lived systems. The usual software maintenance techniques are performed by stopping the system, installing the new version and, finally, starting it. Under this approach, during a period of time the system is not operational and this can lead to various types of problems (economical, damage to company image, safety problems, ) ... .