Essentially a software system's utility is determined by both its functionality and its non-functional characteristics, such as usability, flexibility, performance, interoperability and security. Nonetheless, there has been a lop-sided emphasis in the functionality of the software, even though the functionality is not useful or usable without the necessary non-functional characteristics. In this chapter, we review the state of the art on the treatment of non-functional requirements (hereafter, NFRs), while providing some prospects for future directions.

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On Non-Functional Requirements in Software Engineering

Vaitoskirja pyrkii vastaamaan kahteen kysymykseen: Onko mahdollista muotoilla tuotannon teoriaa? Jos on, johtaako teoria tehokkuuden kohoamiseen, kun sita sovelletaan rakentamiseen?

Historiallinen analyysi paljastaa, etta 1900-luvulla on kehitetty ja sovellettu kolmea eri tuotannon kasitteellista mallia. Tuotanto on nahty muunnoksena, virtana ja arvontuottona. Kaikkia naita malleja voidaan perustellusti pitaa valttamattomina tuotannon ymmartamiseksi, ja niita tulisi siten soveltaa rinnakkain. Vaitostutkimuksessa esitettavaa tuotannon mallia kutsutaan tuotannon TFV-teoriaksi (Transformation, Flow, Value generation).

Tutkimuksen tulokset osoittavat, etta tehokkuutta alentavia ongelmia esiintyy yleisesti rakentamisen kaikissa vaiheissa: rakennuttajan paatoksenteossa, suunnittelun ohjauksessa ja rakennustuotannon ohjauksessa. TFV-teoria selittaa suurelta osin rakentamisen ongelmien syntymisen. Tarkasteltaessa pioneeriyritysten kehittamishankkeita, joissa on sovellettu TFV-teorian tiettyja ydinpiirteita, voidaan havaita, etta talle teorialle perustuvat menetelmat tuottavat merkittavia kustannussaastoja ja muita hyotyja. TFV-teorian avulla voidaan siten suunnata uusiin tehokkaampiin menetelmiin tahtaavaa kokeilua ja kehitystyota seka rakentamisen kaytannon etta tutkimuksen piirissa.

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An exploration towards a production theory and its application to construction

Cognitive engineering

Requirements traceability is intended to ensure continued alignment between stakeholder requirements and various outputs of the system development process. To be useful, traces must be organized according to some modeling framework. Indeed, several such frameworks have been proposed, mostly based on theoretical considerations or analysis of other literature. This paper, in contrast, follows an empirical approach. Focus groups and interviews conducted in 26 major software development organizations demonstrate a wide range of traceability practices with distinct low-end and high-end users of traceability. From these observations, reference models comprising the most important kinds of traceability links for various development tasks have been synthesized. The resulting models have been validated in case studies and are incorporated in a number of traceability tools. A detailed case study on the use of the models is presented. Four kinds of traceability link types are identified and critical issues that must be resolved for implementing each type and potential solutions are discussed. Implications for the design of next-generation traceability methods and tools are discussed and illustrated.

Toward reference models for requirements traceability

Innovative uses of global and local networks of linked computers make new ways of collaborative working, learning, and acting possible. In Group Cognition Gerry Stahl explores the technological and social reconfigurations that are needed to achieve computer-supported collaborative knowledge building--group cognition that transcends the limits of individual cognition. Computers can provide active media for social group cognition where ideas grow through the interactions within groups of people; software functionality can manage group discourse that results in shared understandings, new meanings, and collaborative learning. Stahl offers software design prototypes, analyzes empirical instances of collaboration, and elaborates a theory of collaboration that takes the group, rather than the individual, as the unit of analysis.Stahl's design studies concentrate on mechanisms to support group formation, multiple interpretive perspectives, and the negotiation of group knowledge in applications as varied as collaborative curriculum development by teachers, writing summaries by students, and designing space voyages by NASA engineers. His empirical analysis shows how, in small-group collaborations, the group constructs intersubjective knowledge that emerges from and appears in the discourse itself. This discovery of group meaning becomes the springboard for Stahl's outline of a social theory of collaborative knowing. Stahl also discusses such related issues as the distinction between meaning making at the group level and interpretation at the individual level, appropriate research methodology, philosophical directions for group cognition theory, and suggestions for further empirical work.

Group Cognition: Computer Support for Building Collaborative Knowledge

Documenting argumentation (i.e., design rationale) has great potential for serving design. Despite this potential benefit, our analysis of Horst Rittel's and Donald Schon's design theories and of our own experience has shown that there are the following fundamental obstacles to the effective documentation and use of design rationale: (a) A rationale representation scheme must be found that organizes information according to its relevance to the task at hand; (b) computer support is needed to reduce the burden of recording and using rationale; (c) argumentative and constructive design activities must be linked explicitly by integrated design environments; (d) design rationale must be reusable. In this article, we present the evolution of our conceptual frameworks and systems toward integrated design environments; describe a prototype of an integrated design environment, including its underlying architecture; and discuss some current and future work on extending it.

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Making argumentation serve design

This is a detailed summary of research on design rationale providing researchers in software engineering with an excellent overview of the subject. Professional software engineers will find many examples, resources and incentives to enhance their ability to make decisions during all phases of the software lifecycle. Software engineering is still primarily a human-based activity and rationale management is concerned with making design and development decisions explicit to all stakeholders involved.

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Rationale Management in Software Engineering

Hypertext systems and other complex information stores offer little or no guidance in helping users find information useful for activities they are currently engaged in. Most users are not interested in exploring hypertext information spaces per se but rather in obtaining information to solve problems or accomplish tasks. As a step towards this we have developed the JANUS design environment. JANUS allows designers to construct artifacts in the domain of architectural design and at the same time to be informed about principles of design and the reasoning underlying them. This process integrates two design activities: construction and argumentation. Construction is supported by a knowledge-based graphical design environment and argumentation is supported by a hypertext system. Our empirical evaluations of JANUS and its predecessors has shown that integrated support for construction and argumentation is necessary for full support of design.

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JANUS: integrating hypertext with a knowledge-based design environment

A number of systems have been built which integrate the knowledge representations of hypermedia and knowledge-based systems. Experiences with such have shown users are willing to use the semi-formal mechanisms of such systems systems leaving much structure implicit rather than use the formal mechanisms provided. The problem remains that it is hard (1) to encode knowledge in the formal languages required by knowledge-based systems and (2) to provide support with the semi-formal knowledge found in hypermedia systems. Incremental formalization enables users to enter information into the system in an informal or semi-formal representation and to have computer support for the formalization of this information. The domain independent Hyper-Object Substrate (HOS) differs from other systems that integrate hypermedia and knowledge-based system styles of representations in that it enables the incremental addition of formalism to any piece of information in the system. HOS actively supports incremental formalization with a set of tools which suggest new formalizations to be added to the information space. These suggestions are based on patterns in the informally and semi-formally represented information and the existing formalized knowledge in the information space. An important assumption is that suggestions need not be completely accurate to be of general benefit to users. These suggestions provide a starting point which can be edited, thus changing part of of formalization from creation to modification. XNetwork, an environment the process supporting the design of computer networks, is one of several applications that have been created with HOS. Experiences with HOS show that its flexibility for incrementally adding and formalizing information is useful for the rapid prototyping and modification of semi-formal information spaces.

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Raymond McCall

Papers

Making argumentation serve design

Rationale Management in Software Engineering

Making argumentation serve design

JANUS: integrating hypertext with a knowledge-based design environment

Supporting knowledge-base evolution with incremental formalization