No.4 ESS: Maintenance Software

Abstract

To ensure quality service, a toll switching system must be able to meet very stringent dependability and maintainability requirements. To meet these requirements a large package of maintenance software has been developed. This software consists of four functional areas. The first area deals with the detection and recovery from software malfunctions. These malfunctions include failing defensive program checks, scheduling irregularities, and mutilated data. The second area is concerned with the recovery from hardware faults. Hardware fault recovery is stimulated by a failing hardware check and is completed when the system has been reconfigured around the faulty unit. The third area is concerned with the diagnostic programs that aid the craftsperson in the identification and repair of the faulty unit. The fourth area provides for overall coordinated system recovery from multiple or very severe hardware and software malfunctions.

Documenting architectures with patterns

“…Resulting Context: The maintenance subsystem should perform routine exercises [28] to continually test components in real service. Because People Know Best [1] tells us that humans can sometimes more quickly identify faults than systems can, the Maintenance Software should allow humans to demand that certain functions occur on different schedules.…”

On Deriving Statecharts Supervision Models from SDL Specifications Using SSM

“…Although both approaches have been shown to achieve a reduction in software failures, they have not proved to be cost-effective [22,23]. Another approach is software audits [9] . ln this approach, software data errors are detected and possibly corrected by means of audit programs.…”

No. 4 ESS: Evolution of the Software Structure

“…In the software, we have developed a large program package to provide maintenance functions. 3 This maintenance software package consists of four functional areas that play an essential role in providing the maintenance capabilities of the No. 4 ESS: (i) fault recovery; (ii) diagnostics; (Hi) system reinitialization and recovery; and (iv) system integrity and audits.…”