A Systems Perspective on the Quality Description of Software Components

In this paper we present our rational for proposing a conceptual model for the description of quality attributes of software artifacts, in particular suited to software components. The scientific foundations for our quality description model are derived from researching systems science for its value to software engineering. In this work we realized that software engineering is concerned with a number of interrelated conceptual as well as concrete systems. Each of them exhibits the basic system theoretic principles and is strongly related to certain types of qualities. Such qualities receive particular attention in the context of large software systems, where systems are a combination of in-house and third party products and are increasingly integrated by means of software component technology. Consequently, a quality data sheet is needed by component users to gain trust in, and to evaluate the possible employment of, a candidate component. Interestingly, the concept of a software component appears in most of the aforementioned different types of systems. Hence, it is an excellent means to carry quality related information that belonged to different spheres up to now. The qualities range from those related to the development economics to those related to the execution performance. This paper is an extended version of the paper presented at the 6th World Multiconference on Systemics, Cybernetics and Informatics (SCI2002), Orlando, July 14-18, 2002, Vol. VII, p. 250-255.

Otto Preiss, Alain Wegmann

In this paper we present our motivations for proposing of a generic model for the description of quality attributes of software artifacts, in particular suited to software components. The conceptual ideas for our quality description model are derived from researching systems science for its value to software engineering. In this work we realized that software engineering is concerned with a number of different systems, e.g., a development project as a concrete, human activity, system, a software product in the form of programming code as a conceptual system, a software system running in its execution environment as a concrete system. Each of these systems exhibits the basic system theoretic principles and in the context of this paper is strongly related to certain types of qualities. Such qualities receive particular attention in the context of large software systems, where systems are typically a combination of in-house and third party products and are increasingly integrated by means of software component technology. Consequently, quality related information (in the form of a quality data sheet) is needed by component users to gain trust in and to evaluate the possible employment of a candidate component. Interestingly, the concept of a software component appears in most of the aforementioned different types of systems. Hence, they can be an excellent means to carry quality related information that belonged to different spheres up to now. The qualities range from those related to the development economics to those related to the execution performance.

2002

Foundations of systems and properties

Otto Preiss

Engineering of software-intensive systems is concerned with the creation and evolution of systems that shall exhibit desired properties in their execution as well as development environment. In this context, the motivation of this thesis, derived from current development practice, was twofold. Firstly, software development methods are increasingly required to extend their scope of applicability towards systems engineering. As a consequence, their modeling approaches must be able to cope with a larger diversity of systems and consequently a larger diversity of properties. But these approaches still need to provide a smooth transition to software modeling. Secondly, non-functional properties, which are largely a result of this implicit systems scope, play a major role in the way we design our software-intensive systems. The conceptual aids of current development methods, however, are still less mature in their explicit support for non-functional properties compared with their ability to support functional ones. The principal objective of this thesis is to contribute toward an improved model-based treatment of non-functional properties in development methods. Because we cannot discuss properties independently of the objects they are ascribed to, this objective amounts to a progression from modeling of software and its properties to modeling of interrelated systems and their properties. To address this aim a philosophy of properties and systems is proposed. The philosophy is expressed as a holistic conceptual model of properties and/of systems. It is complemented with some basic rules, which we call tenets. Tenets formulate how we use the philosophical knowledge. The conceptual model offers the foundations for a more generalized understanding of those fundamentally different types of systems and different types of properties that are relevant in software-intensive systems engineering. The generality of our holistic model draws the benefits from our investigations in the areas of systems science, cognitive science, and basic philosophy. The model helps to scrutinize and make sense of the large amount of data in the literature about "non-functional" issues in software engineering. The model is applicable in the derivation of methodological building blocks that can be incorporated into development methods. The building blocks include (a) a general model to discover stakeholders and properties for a given system, (b) a principled manner to trace the fundamentally different types of properties through hierarchies of systems, and (c) a proposal for the representation of systems, their properties and property traces in the UML. The concrete application of the gained knowledge to software engineering results in a proposal for a context-sensitive, customizable quality attribute model. It also results in a proposal on how to structure quality descriptions of software components. In order for such descriptions to be standardized and possibly tool-automated, this thesis proposes to utilize the Reusable Asset Specification and suggests alternatives for its XML-based representation.

EPFL2004

Stakeholder Discovery and Classification Based on Systems Science Principles

Otto Preiss, Alain Wegmann

It is the goal of our research work to elaborate on improvements to the software development methods so that quality attributes can be handled more systematically. By quality attributes we mean the large group of typically systemic properties of a software system, such as availability, security, etc., but also reusability, maintainability and many more. We define quality attributes as stakeholder-centric conditions on the behavior or structure of a system. The importance of the notion of a stakeholder cannot surprise, but the lack of a general theory on how to define and identify the relevant set of stakeholders does. Drawing from systems theory we claim that four basic, generic types of stakeholders are sufficient to be able to derive a specialized set of stakeholders for any considered system and domain of inquiry. It is only when we understand the generic concepts and principles behind quality properties of systems, that we can properly derive methods and build tools to cope with them.

2001

Foundations of systems and properties

Otto Preiss

EPFL2004