The influence of software structure on reliability

ABSTRACT

This paper assumes software structure to be characterized by the interfaces between subsystems or modules. Reliability is considered to be a measure of the extent to which the system can be expected to deliver usable services when those services are demanded. It is argued that reliability and correctness (in the sense used in current computer literature) are not synonyms. The differences suggest techniques by which the reliability of software can be improved even while the production of correct software remains beyond our reach. In general, the techniques involve considering certain unpleasant facts of life at an early stage in the design process, the stage where the structure is determined, rather than later. An appendix gives some specific examples of questions which, if they are thoughtfully considered early in the design, can lead to more reliable systems.

REFERENCES

• 1: Parnas, D.L., "Information Distribution Aspects of Design Methodology", Proceedings of IFIP Congress 1971.
• 2: D. L. Parnas, On the criteria to be used in decomposing systems into modules, Communications of the ACM, v.15 n.12, p.1053-1058, Dec. 1972 [doi>10.1145/361598.361623]
• 3: Parnas, D.L., "Some Conclusions from an Experiment in Software Engineering", Proceedings of the 1972 FJCC.
• 4: Kaiser, C., Krakowiak, S., "An Analysis of Some Run-Time Errors in an Operating System", Aspects Théoriques et Pratiques des Systèmes d'Exploitation, IRIA, Rocquencourt, April 1974.
• 5: Parnas, D.L., "On the Response to Detected Errors in Hierarchically Structured Systems", Technical Report, Carnegie-Mellon University, 1972.

INDEX TERMS

Primary Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
      D.2.4 Software/Program Verification
          Subjects: Reliability

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
      D.2.4 Software/Program Verification
          Subjects: Correctness proofs
      D.2.5 Testing and Debugging
          Subjects: Error handling and recovery

General Terms:
Performance, Reliability, Verification

Keywords:
Error correction, Error handling, Interfaces, Modules, Reliability, Software structure