HAZOP inspections of UML models


To apply Hazard and Operability Studies (HAZOP) to UML models in order to provide an effective and efficient inspection method.


The contact for this research project is here.

PhD Thesis:

The research project has been summarized in a PhD thesis presented at the Gdansk University of Technology in October 2007. The language of the thesis is Polish.

Aleksander Jarzębowicz:
"Metoda wykrywania anomalii w wybranych modelach systemów informatycznych"
(A method for anomaly detection in selected models of information systems)
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The general objective of every software project can be defined as: to deliver, within the budget and schedule constraints, a product satisfying the stakeholders' needs. In practice, however, many software projects fail to meet this objective. One of the contributing factors is errors introduced during early development phases (requirements elicitation, analysis, higher level design). Such errors manifest themselves as anomalies in project documentation, especially in documents created early in the system lifecycle. Those anomalies can be of different kinds, e.g. design defects (wrong representation of a problem domain or a solution), failing to satisfy desired metrics or heuristics or violation of specific system attributes like safety or security. An anomaly which goes undetected reappears in the subsequent representations downstream the development process and the cost of its removal increase rapidly. This creates a strong motivation to detect such anomalies as early as possible within the software lifecycle. The detecting methods are employing the ideas of inspections and reviews and are focusing on system documentation.

This research focuses on detecting anomalies in system models especially object models expressed in UML. These models are created early in a development lifecycle. They have formalised structure and syntax which provide for defining precise criteria and procedures of the inspection process. The aim of this research is to propose a new inspection method dedicated to detecting anomalies in such models.


Hazard and Operability Studies (HAZOP) is known as an effective method of hazard analysis. It is used to detect dangerous events in system's behaviour which may threaten its environment. It has been successfully applied to a number of models created using various notations. Most proposals of application of HAZOP to UML focus on hazard analysis. Hazards are however not only kind of faults that can be found using mechanism of HAZOP. Another category could be design defects which are results of improper mapping of real world concepts into object model are also an interesting subject for HAZOP application. In industrial practice design defects are usually detected by inspections. The adaptation of HAZOP to UML models to detect design defects may provide a useful reading technique for object models inspection.

HAZOP technique uses a set of guidewords - short phrases which purpose is to suggest in a general way various deviations from the correct state. HAZOP guidewords obtain their interpretation relative to the particular UML diagram and UML elements used by it (e.g. class, association, generalization, attribute etc.). The guidewords and their interpretations are applied to a given UML model to generate HAZOP tables - kind of checklists containing suggestions of possible deviations that drives the analyst's attention during the analysis process. The analysis has a form of an individual or group inspection during which the model is interpreted against the checklist of its possible deviations which results in the list of suggested anomalies. The confirmed anomalies are fed back to the development process to be dealt with according to the applied Quality Assurance practices.

The research scope includes: defining a general framework for applying HAZOP to UML models, defining detailed analysis criteria for UML diagrams (interpretations of the HAZOP guidewords applied to particular UML elements), performing real case studies, performing experimental comparison of UML-HAZOP and other review methods, identification and measurement of major factors affecting the efficiency and effectiveness of the method and development of a supporting tool.

It is also planned to investigate the applicability of the proposed solutions to the problem of analysis and validation of ontologies.


  • The project started in 2002.
  • In 2002-2003 a supporting tool was developed within the scope of the EU 5th Framework IST-1999-12040 DRIVE project.
  • In 2002-2005 a number of industrial case studies and controlled experiments were carried out to investigate the potential and limitations of the approach.
  • In 2005-2006 new version of supporting tool was developed.
  • In 2007 PhD thesis was prepared and submitted.


Research results include the following:

  • Adaptation of HAZOP to defects analysis of UML models,

  • Four industrial case studies aiming at defects analysis of UML models,

  • Definition and implementation of a tool supporting the method,

  • Three controlled experiments comparing HAZOP with other review techniques and utilisation of feedback.

The final goal is to provide a thoroughly validated and optimised inspection method. This however still requires extended practical application of the method in industrial case studies and experimental research. Also, to be most helpful, inspection method should be applicable to the modelling techniques and notations which are currently used.


    All up to date publications related with this research subject are listed below. Draft versions of English papers in PDF format are available for download.

  1. Jarzebowicz A., Gorski J.: Empirical evaluation of reading techniques for UML models inspection, International Transactions on Systems Science and Applications, Vol. 1, No. 2 (2006)
    Download PDF (145 kB)

  2. Gorski J., Jarzebowicz A.: Development and validation of a HAZOP-based inspection of UML models, 3rd World Congress for Software Quality, 26-30 September 2005, Munich, Germany
    Download PDF (121 kB)

  3. Jarzebowicz A., Gorski J.: Experimental comparison of UML-HAZOP inspection and non-structured review, Foundations of Computing and Decision Sciences, Vol. 30 (2005), No. 1, pp. 29-38.
    Download PDF (130 kB)

  4. Jarzebowicz A., Gorski J.: Eksperymentalne porównanie inspekcji UML-HAZOP z przeglądem niestrukturalnym, 6th National Conference on Software Engineering, 5-8 October 2004, Gdansk, Poland (in Polish).

  5. Gorski J., Jarzebowicz A., Leszczyna R., Miler J., Olszewski M.: Tool support for detecting defects in object-oriented models, Proceedings of 10th International Multi-Conference on Advanced Computer Systems (ACS 2003), 22-24 October 2003, Miedzyzdroje, Poland.
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  6. Jarzebowicz A.: Zastosowania metody HAZOP w inżynierii oprogramowania, 15th Summer Conference of Polish Information Processing Society, 23-26 June 2003, Szczyrk, Poland. (in Polish)

  7. Gorski J., Jarzebowicz A., Leszczyna R., Miler J., Olszewski M.: Wspomaganie wykrywania defektów w modelach obiektowych, 1st National Conference on Information Technologies, 18-21 May 2003, Gdansk, Poland. (in Polish)

  8. Gorski J., Jarzebowicz A.: Detecting defects in object-oriented diagrams using UML-HAZOP, Foundations of Computing and Decision Sciences, Vol. 27 (2002), No 4.
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  9. Gorski J., Jarzebowicz A.: Wykrywanie anomalii w modelach obiektowych za pomocą metody UML-HAZO, 4th National Conference on Software Engineering, 16-18 October 2002, Poznan-Tarnowo Podgorne, Poland. (in Polish)

  10. Jarzebowicz A.: Wspomaganie analizy systemu informatycznego metodą dewiacji przepływów, M. Sc. thesis, Department of Software Engineering, Gdansk University of Technology, September 2002. (in Polish)