Defeasible Argumentation of Software Architectures

Defeasible argumentation is typical of legal and scientific reasoning. A defeasible argument is one in which the conclusion can be accepted tentatively in relation with the evidence known so far, but may need to be retracted as new evidence comes in. This paper analyses the role of defeasible argumentation in the explanation and evaluation of architectural decisions. We analyse technical explanations offered by engineers at Twitter and eBay about several architectural decisions adopted in those systems. We generalize these examples in four argumentation schemes. We also study the typical case of reasoning with a formal model of an architecture, and we infer a fifth argumentation scheme. Finally, we apply Hastings’ method of attaching a set of critical questions to each scheme. We show that the existence of critical questions reveals that the inferred schemes are defeasible: in argumentation theory, if a respondent asks one of the critical questions matching a scheme and the proponent of an argument fails to offer an adequate answer, the argument defaults and the conclusion is retracted. This dialogical structure is the basis of typical architectural evaluations. We conclude that the provided evidence supports the hypothesis that defeasible argumentation is employed in architectural evaluation. In this context, a rich catalogue of argumentation schemes is a useful tool for the architect to organize his or her reasoning; critical questions assist the architect in identifying the weak points of his or her explanations, and provide the evaluation team with a checklist of issues to be raised.Universidad de Sevilla VPPI-U

TOWARDS A RESEARCH METHOD FOR THEORYDRIVEN DESIGN RESEARCH

In this paper we outline a new methodical approach for integrating theories into the design research process. Incorporating theories in design projects allows design researchers to reason on the effects of the IT artifact prior to its realization. We argue that design decisions should be transparent claims of utility based on theory-grounded arguments. Documenting design decisions requires the design researcher to integrate appropriate theories and document the rationale behind a particular design decision. Overall, we demonstrate on the example of constructing a new modeling grammar how to integrate theories in the design research process and discuss conflicts which occur when applying these theories

Justifying design decisions with theory-based design principles

Although the role of theories in design research is recognized, we show that little attention has been paid on how to use theories when designing new artifacts. We introduce design principles as a new methodological approach to address this problem. Design principles extend the notion of design rationales that document how a design decision emerged. We extend the concept of design rationales by using theoretical hypotheses to support or object to design decisions. At the example of developing a new conceptual modeling grammar we demonstrate two main benefits of using design principles. First, the link between theory and design decision enables the design researcher to reason about the resulting behavior of the IT artifact prior to instantiation. Second, design principles allow deducing empirically testable hypotheses to foster the rigorous evaluation of IT artifacts

Managing the requirements engineering process

Process management is a crucial issue in developing information or computer systems. Theories of software development process management suggest that the process should be supported and managed based on what the process really is. However, our learning from an action research study reveals that the requirements engineering (RE) process differs significantly from what the current literature tends to describe. The process is not a systematic, smooth and incremental evolution of the requirements model, but involves occasional simplification and restructuring of the requirements model. This revised understanding of the RE process suggests a new challenge to both the academic and industrial communities, demanding new process management approaches. In this paper, we present our understanding of the RE process and its implications for process management.<br /

Conceptual modeling for the design of intelligent and emergent information systems

A key requirement to today's fast changing economic environment is the ability of organizations to adapt dynamically in an effective and efficient manner. Information and Communication Technologies play a crucially important role in addressing such adaptation requirements. The notion of `intelligent software' has emerged as a means by which enterprises can respond to changes in a reactive manner but also to explore, in a pro-active manner, possibilities for new business models. The development of such software systems demands analysis, design and implementation paradigms that recognize the need for ‘co-development’ of these systems with enterprise goals, processes and capabilities. The work presented in this paper is motivated by this need and to this end it proposes a paradigm that recognizes co-development as a knowledge-based activity. The proposed solution is based on a multi-perspective modeling approach that involves (i) modeling key aspects of the enterprise, (ii) reasoning about design choices and (iii) supporting strategic decision-making through simulations. The utility of the approach is demonstrated though a case study in the field of marketing for a start-up company

Evolutionäre Referenzmodelle: Anforderungen an eine methodische Unterstützung zur systematischen Wiederverwendung und Weiterentwicklung von modellhaft aufbereitetem Wissen

Konzeptuelle Modelle sind zur Gestaltung und Steuerung von Informationssystemen ein akzeptiertes und weit verbreitetes Instrument. Sie werden sowohl zur Gestaltung der Organisationsstruktur als auch zur Entwicklung der unterstützenden IT-Systeme verwendet. Für diesen Aufgabenbereich existiert eine hohe Nachfrage nach externer Unterstützung, da spezifische Fachkenntnisse und Erfahrungen notwendig sind. In diesem Zusammenhang werden seit Jahrzehnten Ansätze zur Wiederverwendung in Wissenschaft und Praxis diskutiert. Die Akzeptanz und Verbreitung von explizit zur Wiederverwendung konstruierten Modellen (Referenzmodelle) bleiben jedoch deutlich hinter den Erwartungen zurück. Die vorliegende Arbeit trägt zur Untersuchung möglicher Ursachen für den ausbleibenden Erfolg von Referenzmodellen bei. Der Forschung liegt die Vermutung zugrunde, dass die Potentiale von Referenzmodellen nicht zufriedenstellend ausgeschöpft werden können, weil die existierenden bzw. verwendeten Modellierungsmethoden die theoretischen Anforderungen an die Wiederverwendung von modellhaft dargestellten Lösungen zur Unternehmensgestaltung nicht erfüllen. Die vorliegende Arbeit fasst neun Einzelpublikationen zum Themenbereich Evolutionäre Referenzmodelle zu einer kumulativen Dissertation zusammen. Es werden in einem argumentativdeduktiven Verfahren konstruktivistische Theorien zur systematischen Weiterentwicklung und Wiederverwendung konzeptueller Unternehmensmodelle untersucht. Die auf dieseWeise resultierende Erweiterung der allgemeinen Modelltheorie wurde ihrerseits argumentativ-konzeptionell mit Hilfe von semiformalen Argumentationsmodellen aufbereitet. Im Ergebnis werden ein theoretisches Rahmenwerk zur evolutionären Referenzmodellierung präsentiert und 23 konzeptionelle Anforderungen definiert, die eine gezielte Methodenentwicklung für die evolutionäre Referenzmodellierung steuern sollen

Enterprise modelling framework for dynamic and complex business environment: socio-technical systems perspective

The modern business environment is characterised by dynamism and ambiguity. The causes include global economic change, rapid change requirements, shortened development life cycles and the increasing complexity of information technology and information systems (IT/IS). However, enterprises have been seen as socio-technical systems. The dynamic complex business environment cannot be understood without intensive modelling and simulation. Nevertheless, there is no single description of reality, which has been seen as relative to its context and point of view. Human perception is considered an important determinant for the subjectivist view of reality. Many scholars working in the socio-technical systems and enterprise modelling domains have conceived the holistic sociotechnical systems analysis and design possible using a limited number of procedural and modelling approaches. For instance, the ETHICS and Human-centred design approaches of socio-technical analysis and design, goal-oriented and process-oriented modelling of enterprise modelling perspectives, and the Zachman and DoDAF enterprise architecture frameworks all have limitations that can be improved upon, which have been significantly explained in this thesis. [Continues.