Camilo FitzgeraldPhD Student

UCL Computer Science

8th January, 2008

Resolving Conflicts in Requirements Engineering: A PhD Project

• A Simple Example• Scope of the Project• Existing Work• Problem Exploration• Next Steps• Summary

Overview

• Consider a ‘new mobile phone’ project:– Requirement A: Phone must provide GPS.– Requirement B: Phone must weigh less than 10g.– Domain Property: The lightest GPS device weighs 12g.

• Possible resolutions include:– Elimination? Forget about the GPS (Requirement A).– Weakening? The phone may weigh 20g (Requirement B).– Live with Conflict? A GPS device could be available next

week that weighs less.– …

A Simple Example

• In Perspective:– Poor requirements management is the #1 reason for IT project

failures1.– Management of conflicts plays a big part in this.

• Conflicts between requirements are commonplace:– Only a handful of computer aided detection methods exist.– Almost no work done on automated resolution methods.

• Conclusion:– We need better conflict detection/resolution methods and tools.– Ultimately, we need a ‘complete’ requirements conflict

management tool that covers every stage of a projects lifecycle.

Scope of the Project

Key Related Works Explored So Far:• Viewpoints Theory2

• KAOS - Goal Oriented Requirements Engineering3

• XLinkIt - Repair Actions Paper4

• WinWin – Non-Functional Requirements negotiation5

• Egyed’s work on UML model inconsistencies6

Features of these works:

Existing Work

Work I will be looking into next:• Goal modeling with i*7.• Conflicting merges in configuration management.• Models for collaborative elicitation.• The economic approach to conflicts.• I’m very interested in more suggestions…

Existing Work

• OpenOffice Project: – A qualitative analysis of requirement conflicts found in

OpenOffice.org’s spreadsheet application.– Modeling of conflicts, and their resolution strategies.

• Main points of interest:– Resolutions were usually chosen based upon the level of

authority of the actor that proposed them.– Conflicts were frequently raised more than once, after a

resolution had been chosen.– Many examples where the resolution chosen was to ‘live

with the conflict’.

Full analysis available on weblog: http://www.cs.ucl.ac.uk/staff/C.Fitzgerald

Problem Exploration: Case Study

• UCL ‘Research Information Systems’ Project:– Project Aim: To keep complete and up-to-date data on all

research projects at UCL.– Underlying Conflict: Time & effort of academic staff vs.

accuracy of records. • A Study of Student Projects

– MSc students formed groups of ‘Developers’ and ‘Clients’ to produce a requirements document collaboratively.

– A Wiki will be used next year to produce the requirements document. Editing pages collaboratively could be a useful tool for recording and resolving conflicts.

More details on weblog: http://www.cs.ucl.ac.uk/staff/C.Fitzgerald

Problem Exploration: Other Studies

• Possible criteria for choosing alternative resolution strategies:

– Stakeholder satisfaction.– Stakeholder importance.– Pick a resolution that increases the probability of

subsequent resolutions.– Project development stage.– Artefacts altered by a resolution.

• Analyse resolutions in terms of other conflicts that may arise from them:

– How can we handle dependencies between conflicts?– In what order should conflicts be resolved?– At what stage of the project should a conflict be resolved?

Problem Exploration: Ideas

• Looking into:– Characterisation of real world resolution strategies.– Dependencies between conflicts.

• Future Plans:– Continue with the projects and related work.– Find methods for computer aided conflict detection

and/or resolution.– Implement these methods in a simple tool that is of use

to the software engineering community.– Produce a thesis!

Next Steps

• Conflicts exist and need to be managed effectively.• Lots of interesting work out there, but we are a long

off from a complete conflict management solution.• I’m looking into characterisations of the way

conflicts are detected and resolved.• By the end of three years, I aim to have a tool that

will be useful to software engineers.

For more information: http://www.cs.ucl.ac.uk/staff/C.Fitzgerald/

Summary

1 Survey of US software project by Standish Group

2 Finkelstein, A. S., I. (1996). "The Viewpoints FAQ: Editorial - Viewpoints in Requirements Engineering." Software Engineering Journal.

3 Lamsweerde, A. v. and R. Darimont (1998 ). "Managing conflicts in goal-driven requirements engineering " IEEE Transactions on Software Engineering.

4 Nentwich, C., W. Emmerich, et al. (2003 ). Consistency Management with Repair Actions. 25th International Conference on Software Engineering

5 Boehm, B., P. Bose, et al. (1995). Requirements Negotiation and Renegotiation Aids: A Theory-W Based Spiral Approach. 17th International Conference on Software Engineering.

6 Egyed, A. (2007). Fixing Inconsistencies in UML Design Models. 29th International Conference on Software Engineering, ICSE.

7 Yu, E. S. K. (1997). Towards Modelling and Reasoning Support for Early-Phase Requirements Engineering. IEEE International Symposium on Requirements Engineering

References

University College LondonDept. of Computer Science, MPEBLondon WC1E 6BTOffice: 7.08Tel: +44 (0)20 7679 3699 (Direct Dial)Fax: +44 (0)20 7387 1397Email: C.Fitzgerald (at) cs.ucl.ac.ukWeb: http://www.cs.ucl.ac.uk/staff/C.Fitzgerald/

Supervisors: Emmanuel Letier & Anthony

Finkelstein

Contact Information

Camilo Fitzgerald