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School of Mathematics, Computer Science & Engineering


(Diversity with Off-The-Shelf components)

Principal Investigator: Prof Lorenzo Strigini

Contact: Prof Lorenzo Strigini

Funding to CSR, City University: £232,000

Funding Source: EPSRC

Duration: November 2000 - April 2004

DOTS was a collaborative project with our sibling centre at the University of Newcastle-Upon-Tyne.


The DOTS project unifies two strands of research in software engineering: design diversity for fault tolerance, and re-use of off-the-shelf software. It builds on previous work on diversity at the Centre for Software Reliability, and in particular on the DISCS project (Diversity In Safety Critical Software). It is motivated by the increasing industrial interest in using off-the-shelf (rather than bespoke) software for building new systems or applications. Its premises, outlined in this short paper presented at DSN 2000, were in summary:

  • In many applications, the main problem with off-the-shelf components is the difficulty of achieving confidence of sufficient reliability
  • Software fault tolerance (diversity) is a convenient way of increasing system reliability without changing the internals of software modules
  • Software fault-tolerance in the form of modular redundancy with diversity (as in "multiple-version software) becomes affordable and convenient when based on OTS items. This possibility has not been sufficiently studied.
  • Some methods for increasing the dependability of COTS-based systems (e.g. depending on wrappers with filtering or monitoring functions) are actually other examples of software fault tolerance, but have not been studied as such, e.g. to guide architectural decisions to achieve better reliability.

The general goal of this project was to support decisions both in the acceptance of a system including OTS items and in its development, i.e. in the choice and combination of OTS items, their interconnection and system-level verification.

A summary of results. and a list of the project's publications are available.

CSR Personnel: Prof. Lorenzo Strigini (Principal Investigator), Prof. Bev Littlewood, Dr Peter Popov, Ms Claude Gierl, Mr Meine van der Meulen, Mr Vladimir Stankovic, Mr Ilir Gashi.

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version 2.8 Published: 2nd Dec 2004