Dependability and Failure
When defined as "the ability to deliver service that can justifiably be trusted" - dependability has a number of attributes. These include: availability (readiness for correct service); reliability (continuity of correct service); safety (absence of catastrophic consequences); integrity (absence of improper system state alterations); maintainability (ability to undergo repairs) and more. But as we consider broader, socio-technical, notions of "system", the ability to achieve a clear and documented understanding of the intended service of the system - and hence some view of dependability - becomes increasingly difficult.
Once we start taking into account the actual practice of a socio-technical system rather than any idealisation of it, it seems increasingly difficult to determine with sufficient precision what is meant by the "service" the system offers. Thus it also becomes difficult to determine what is meant by a "failure" of that service, and thus what is meant by "dependability" in this broader context. When we start considering people using a computer-based system, the notion of failure becomes rather more complex. In a situation where computer-based systems are used by groups or teams of people, usually in conjunction with other systems, then recognising failure becomes even more difficult because different users may have different models of how the system is supposed to behave. Unexpected behaviour to one user is normal behaviour to another. Some users may have learned how to work-round problems in the system, others may not have.
In DIRC we use our fieldwork observations to detail some aspects of 'failure', to examine the everyday 'workarounds' developed to deal with 'failure''; the lay conceptions of dependability and the relationship between failure and 'normal' troubles. DIRC research on dependability and failure has taken a number of directions:
1. Much of the work on dependability has necessarily, and naturally, focused on massive, extraordinary, public failures such as the London Ambulance Service failure of 1992, the space shuttle catastrophe of 1986, or the Ladbroke Grove train disaster of 1999. In DIRC we examined the public enquiry into the Ladbroke Grove train crash to point to some of the complexities of the organisational background to failure. Our work highlights organisational responses to massive failure and raises and contextualises organizational issues concerning management, scoping, coordination, timing, selection, prioritization, enforcement and agreement suggesting a need to study how these are dealt with as organizational features of everyday work in safety critical settings.
2. DIRC was also concerned with rather more ordinary, everyday instances of dependability and failure. Instances of undependability in many settings are not normally catastrophic, but are rather mundane events that occasion situated practical (as opposed to legal) inquiry and repair. Dependability can then be seen as being the outcome of people's everyday, coordinated, practical actions. This involved directing our attention to the means whereby people cope with, and overcome, the possibility of 'everyday failure' through routine workarounds. We examined this in two settings - a rolling mill in a steel plant and the assembly line in an engine manufacturer. Our research points to elements of a framework within which everyday work and normal natural troubles in socio-technical systems can be understood.
3. DIRC also examined issues of dependability and failure in domestic systems. For domestic systems, the users of the system are central to the design and central to the consideration of dependability. In the home, people do not follow defined operational processes, system users may vary widely and within the same home there may be both techno-phobes and techno-philes. The dependability of home systems is played out daily through the routines and situated actions of the people in the home. Therefore, we contend that the requirements of dependability in the home setting are derived from different roots from traditional dependability models of software design. To achieve dependability, we must take an approach that integrates the user and environment with the technology rather than considering dependability as a property of the technology alone.
1. Voss, A., Procter, R., Slack, R., Hartswood, M., Williams, R. And Rouncefield, M (2001). Production Management as Ordinary Action: An Investigation of Situated, Resourceful Action in Production Planning and Control. In Levine, J. (Ed.) Proceedings of 20th UK Planning and Scheduling (SIG) Workshop, Edinburgh, December 13th-14th, 2001, p. 230-243.
2. Harper, R., Procter, R., Randall, D. And Rouncefield, M. (2001) 'Safety in Numbers: Calculation and Document Re-Use in Knowledge Work'. In Proceedings of the International Conference on Supporting Group Work, Boulder, Colorado, October, 2001. Pp242-251
3. Hartswood, M., Procter, R., Rouncefield, M, Slack, R., Voss, A. and Williams, R. Accomplishing 'Just-in-Time' Production. In Johnson, C. (Ed.) Proceedings of 21st European Annual Conference on Human Decision Making and Control, Glasgow, July 15th-16th, 2002, 209-211.
4. Mark Hartswood, Rob Procter, Roger Slack, Alex Voss and Mark Rouncefield (2002) Information Systems and Workplace Studies: Observing the Contingencies of 'Just-in-Time' Production.In Bhattacharjee, A and Paul, R.J. (eds) Proceedings of the First International Workshop on 'Interpretive' Approaches to Information Systems and Computing research. Brunel University ISBN 1 902316 27 4 pp 67-69.
5. Alexander Vo, Roger Slack, Rob Procter, Robin Williams, Mark Hartswood, Mark Rouncefield (2002) Dependability as Ordinary Action. In: Stuart Anderson, Sandro Bologna, Massimo Felici Computer Safety, Reliability and Security: Proceedings of the 21st International Conference, SAFECOMP 2002. Catania, Italy, September, 2002. Lecture Notes inComputer Science 2434. Springer Verlag, pages 32--43.
6. Alexander Vo, Roger Slack, Rob Procter, Robin Williams, Mark Hartswood, Mark Rouncefield (2002) Dependability as Ordinary Action. In: Stuart Anderson, Sandro Bologna, Massimo Felici Computer Safety, Reliability and Security: Proceedings of the 21st International Conference, SAFECOMP 2002. Catania, Italy, September, 2002. Lecture Notes in Computer Science 2434. Springer Verlag, pages 32--43.
7. Guy Dewsbury, Ian Sommerville, Karen Clarke and Mark Rouncefield, (2003) A Dependability Model for Domestic Systems, In Anderson, Felici and Littlewood (eds), Computer Safety, Reliability, and Security, Computer Safety, Reliability and Security: Proceedings, SAFECOMP Lecture Notes in Computer Science, Springer-Verlag Heidelberg, Volume 2788, pp103-115, ISSN 0302-9743.
8. Clarke, K, Hughes, J., Martin, D, Rouncefield, M., Sommerville, I, Hartswood, M, Procter, R., Slack, R. and Voss, A. (2003) Dependable Red Hot Action. In Dourish, P and Fitzpatrick, G. (Eds.) Proceedings of the European Conference on Computer Supported Cooperative Work, Helsiniki, September, 2003. Pp61-80
Mark Rouncefield (Lancaster)
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