Über die Autorin bzw. den Autor

Cesar Gonzalez-Perez is a senior researcher in the application of information technologies in the management of cultural heritage at the Spanish National Research Council and was previously a researcher in the Department of Software Engineering at the University of Technology, Sydney.

Brian Henderson-Sellers is Director of the Centre for Object Technology Applications and Research and a professor at the University of Technology, Sydney. He is the author of more than a dozen books on object and agent technologies.

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Metamodelling for Software Engineering is a comprehensive and practical guide to a subject that is growing in interest and importance and is becoming the standard way of defining software development methodologies, including both processes and languages such as UML. The ISO/IEC 24744 standard metamodel is adopted throughout the book as a background reference.

Metamodelling is often regarded as a complex discipline, much removed from daily practice. This book seeks to demystify metamodelling and explains why it is necessary in the context of software engineering. It covers:

• Basic concepts and principles of metamodelling.
• Problems associated with traditional metamodelling, alongside an exploration of possible solutions and alternative approaches.
• Advanced topics such as the extension of the object-oriented paradigm for metamodelling purposes, or the foundations of powertype-based tool development.
• A comprehensive case study, which shows how to use the concepts explained in the previous chapters.

This thorough and practical guide bridges the gap between the academic realm, where most of the innovation happens, and industry, where the real needs exist. This book will show academics how to approach metamodelling in such a fashion that their research outcomes are useful to industry; lecturers and educators how to teach metamodelling to students so it is well understood and assimilated; industry methodologists how to utilize valuable metamodelling ideas in their daily work and software tool developers how to incorporate the most innovative research outcomes into their products.

Focusing on metamodelling as a discipline, exploring its foundations, techniques and results and covering process, product and quality issues under a common framework, this is a unique and timely publication for all software engineering practitioners, academics and students interested in metamodelling.

Aus dem Klappentext

Metamodelling for Software Engineering is a comprehensive and practical guide to a subject which is growing in interest and importance and is becoming the standard way of defining a language, such as UML. The process seeks to provide an explicit specification of the constructs and rules of how a domain-specific model (or language) is built.

Metamodelling is often regarded as a complex discipline, much removed from daily practice. This book seeks to demystify Metamodelling and explain why it is necessary in the context of software engineering. It covers:

• Basic concepts and principles of Metamodelling.
• Problems associated with traditional Metamodelling, alongside an exploration of possible solutions and alternative approaches.
• Advanced topics such as the extension of the object-oriented paradigm for Metamodelling purposes, or the foundations of powertype-based tool development.
• A comprehensive case study, which shows how to use the concepts explained in the previous chapters.

This thorough and practical guide bridges the gap between the academic realm, where most of the innovation happens, and industry, where the real needs exist. This book will show academics how to approach Metamodelling in such a fashion that their research outcomes are useful to industry; lecturers and educators how to teach Metamodelling to students so it is well understood and assimilated, industry methodologists how to utilize valuable Metamodelling ideas in their daily work and software tool developers how to incorporate the most innovative research outcomes into their products.

Focusing on Metamodelling as a discipline, exploring its foundations, techniques and results and covering process, product and quality issues under a common framework, this is a unique and timely publication for all software engineering practitioners, academics and students interested in Metamodelling.

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Metamodelling for Software Engineering

John Wiley & Sons

Chapter One

A major area of interest within the computing discipline of software engineering is that of software development methodologies. A methodology has several constituent parts including a full lifecycle process, a comprehensive set of concepts, a set of rules, heuristics and guidelines underpinning appropriate development techniques, a set of metrics, information on quality assurance, a set of coding and other organizational standards, and advice on reuse and project management. In order to describe all these parts in a consistent and useful manner, we need some kind of formalism. The formalism chosen here is that of metamodelling.

We begin this book with an examination of what is meant by a methodology and how metamodelling can be useful in creating robust and effective methodology models. Later we describe how the basic metamodelling ideas can be used in various domains, such as for modelling work products and processes. We evaluate the current state-of-the-art in these and other application areas before introducing some advanced ideas and how they have led to the creation of international standards that support the development of industry-strength methodologies for use in professional, commercial software development endeavours.

1.1 WHAT IS A METHODOLOGY?

Dictionaries often provide two basic meanings for the word "methodology". On the one hand, a methodology is an approach to doing something; on the other hand, methodology is the study of methods. According to WordNet, a methodology is "the system of methods followed in a particular discipline", a method being "a way of doing something, esp. a systematic one". Also according to WordNet, methodology means "the branch of philosophy that analyzes the principles and procedures of inquiry in a particular discipline". Therefore, the two possible meanings of "methodology" are:

The collection of methods followed in a particular discipline.

The study of methods followed in a particular discipline.

These two accepted meanings are closely related but are clearly different. The first one refers to a piece of information that describes how things are done within a given discipline. The second one refers to the activity of studying how things are done within a given discipline. The first usage is common and widely accepted, although the second one is closer to the etymological origin of the word "methodology" since the -ology suffix means "study of", in Greek.

It is also worth emphasizing that the first accepted meaning, denoting a thing (a piece of information), corresponds to a countable noun: it is possible to speak about one methodology or multiple methodologies, and the article is always used in the singular (e.g. "this methodology is flawed"). The second accepted meaning, in contrast, corresponds to an uncountable noun, very much like "biology" or "archaeology": we usually omit the definite article ("biology is exciting" rather than "the biology is exciting"). Most uses of the word "methodology" in the realm of engineering pertain to the first meaning; it is very common to hear people speaking about this or that methodology, but extremely uncommon to hear people saying things like "methodology is an exciting area to work in" (this would sound much better with any other "-ology" noun). This is a grammatical reason that supports the first meaning of "methodology" better than the second.

Also, the first meaning relates the terms "methodology" and "method" by a whole-part relationship (i.e. a methodology is a system or collection of methods), whereas the relationship implicit in the second meaning is much more complex (methods are studied by methodology). Interestingly, most uses of "method" and "methodology" in engineering tend to blur the semantic differences between them: a method is a systematic way of doing something and a methodology is a collection of methods, which, appealing to common sense, also defines a way of doing something. This fits well with the first meaning of "methodology" and is a semantic reason that supports the first meaning of "methodology" better than the second.

Finally, the second meaning of "methodology" pertains to philosophy and is rarely used without a connection to this field. Although modelling and metamodelling have strong connections to cognitive science and psychology, we believe that the three reasons here outlined are important enough as to encourage the adoption of the first meaning of "methodology" as far as engineering disciplines are concerned. Therefore, we can say that:

A methodology is a systematic way of doing things in a particular discipline.

This definition places the concept of "methodology" very close to that of "method"; as we said above, a collection of ways to do things ("methods", according to the dictionary) is also, using common sense, a way to do things. This means that, for practical purposes, and as far as this book is concerned:

A method is a methodology: the two terms are synonymous.

1.1.1 Further Characterization

Let us dig deeper into the definition of what a methodology is. We will do this by analyzing the phrase "a systematic way of doing things in a particular discipline".

To start with, and central to the definition, a methodology is a way. In other words, it is a manner, a means, a course of conduct. This means that no methodology is an end in itself but is a means to an end. It also means that, being a manner, it is arguable that other alternative manners also exist.

In addition, a methodology is systematic, i.e. orderly, planned and, at least to a certain extent, predictable. If we assume that methodologies are often shared by multiple individuals, this means that subjectivity must be reduced to a minimum in methodologies; otherwise, they wouldn't be systematic in an objective way.

Furthermore, a methodology is a way of doing things. This means that methodologies can be applied to change the state of the world that surrounds us (i.e. to do things), becoming the cause of effects that should be observable. If this were not so, the methodology wouldn't be doing things. Also, the things done by use of a methodology are the persistent outcomes of its application; the methodology is applied in order to obtain these outcomes. In other words, the things done by a methodology encompass the purpose of the methodology as a whole. The methodology is used because some community pursues that purpose.

Finally, any given methodology pertains to a particular discipline. In other words, it is focussed on a particular domain of knowledge and, consequently, works within a particular conceptual environment. In this book, our focus is the discipline of software engineering i.e. building a software application that meets the user's stated requirements.

As a summary, we can say that methodologies are used by communities that work in well-defined fields in order to produce persistent outcomes in their environment in an orderly and predictable fashion. For example, a team of software developers (the community) may use Extreme Programming (a methodology) in the field of information systems development in order to produce a working system (the persistent outcome) by following some techniques, such...