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European Space Agency (ESA)

In August 2008, after years of experimentation with VisioModeler, the European Space Agency issued an invitation to tender for an "ORM Tool - preferably based on NORMA" to help with defining and developing satellite projects.

2011 note: This project evolved into an ESA working group on "Fact Based Modeling". For further information and project status contact the European Space Agency.

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My Msc Dissertation

This nine month project included extensive literature research plus a survey and an experiment.

The literature research and the experiment support the view that UML and ER methods have major problems because they are based on non-standard and informal methods.

The survey showed that many developers see their role as describing the "real world". In other words, they seem to think that their job is similar to that of a cartographer who draws a map of something that already exists such as a country or a city.

However, my research and that of Dr Simsion shows that this is not the case. It appears that the software developers job is about creating a new piece of reality rather than describing something "out there" that already exists.

Developers often mention "domain experts". However, it appears that during the development process, developers discover that many domain experts have only an informal understanding of their domain.

Survey results

An interim report of the "Design or description" survey was posted to the Library on 24 May 2008. Registered members of this website can download this and other documents from the Library.

Registration is free. To register, just click on the "Join" button at the top right hand side of your screen.

Survey 1: Is data modeling a descriptive process or a design process?

Descriptive tasks are based on the assumption that the "something" that you are to describe already exists. On the other hand, design is a creative task and there is no presumption of a pre-existing "something".

Dr Graeme Simsion believes that the answer to the "Describe or design?" question sets the context for data modeling. Is the Universe of Discourse (UoD) a reality that is "out there" just waiting to be described by the data modeler or is the UoD created during the data modeling process? In 2007, Dr Graeme Simsion published the results of his PhD research in the book "Data Modeling: Theory and Practice". (For details of the book, just click on the image below ). Dr Simsion kindly agreed to allow me to use his work as the basis of my survey.

You may visit the Survey forum and vote on the question. "Is data modeling a descriptive process or a design process?"

Books: Click an image for details

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Research

Some of the research mentioned on this page was designed to support my dissertation project for the award of a Master of Science Degree in Information Systems Management from the University of Liverpool.

Is ORM more effective than other methods? Many people claim that ORM is more effective than other methods. However, to the best of my knowledge, until now, there has never been a scientific investigation into this claim. So I designed my experiment to test the hypothesis that "ORM is at least 25% more effective than ER and UML"

My dissertation project was completed on 28 August 2008 and the examiners at the University of Liverpoool graded my dissertation project as an "A". My findings confirmed the hypothesis that "ORM is at least 25% more effective than ER and UML".

You can see the details of the experiment by clicking on the links in the following text.

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The Experiment aims to provide data to test the hypothesis that ORM is at least 25% more effective than approaches based on either ER or UML. The experiment was managed via this website but the experiment itself was conducted by volunteers with an average of 4.7 years experience in modeling techniques.

The experiment has a standard input text of just 331 words which describes some of the functions in an imaginary airline. The experimental procedure required each participant to convert the 331 words into a UML "data only" class diagram using one of the three methods described in the briefing packages.

All three experimental packages require that the person who does the experiment has sufficient UML skill to create a UML "data only" class model. The differences between the packages are explained below.

UML briefing package: This package is for people who have UML skills. This procedure asks that you use the "standard UML approach" defined at http://www.ibm.com/developerworks/rational/library/5383.html . This approach requires that you begin by creating UML use case(s) and then use the UML use cases to create a UML "data only" class model.
Click for the UML briefing package

ER briefing package: This package is for people with both ER and UML skills. This procedure asks that you use any ER technique to create an ER model and then convert the ER model to a UML "data only" class model.
Click for the ER briefing package

ORM briefing package: This package is for people with both ORM and UML skills. This procedure asks that you use one of three popular ORM tools (VisioModeler, VEA or NORMA) to create an object-role model and then convert the object-role model to a UML "data only" class model. The briefing document contains a summary of the ORM to UML conversion procedure that is explained on page 389 of Terry's "Big Brown Book" (Information Modeling and Relational Databases: Second Edition, Halpin & Morgan 2008). However, you can use any ORM-UML conversion method that you prefer.
Click for the ORM briefing package

Each of the foregoing procedures has a link to a separate online questionnaire that allows participants to post their results directly into an online database.

All results are anonymised. No personal details were revealed in my dissertation document or will be revealed to any third party.

14 November 2008: Dissertation Results

I submitted my dissertation document on 28 August 2008. Two independent assessors graded my work. In early November 2008, my dissertation was graded "A" by the University of Liverpool Board of Examiners and I received an overall distinction for my MSc work.

I would like to thank those persons who contributed to my experiment.

Ken Evans

ken.evans@ormfoundation.org