SOFTWARE QUALITY FROM SYSTEMS PERSPECTIVE

Transcription

1 CSECS 2015, pp The 11th Annual International Conference on Computer Science and Education in Computer Science June , Boston, MA. USA SOFTWARE QUALITY FROM SYSTEMS PERSPECTIVE Latchezar Tomov, Valentina Ivanova, New Bulgarian University - Sofia, Department of Informatics Abstract: Software quality perspectives include different viewpoints user viewpoint, management viewpoint, engineering viewpoint. This paper develops perspective and definition of quality from systems viewpoint. The software product, the company that develops it, the people who use it and the processes on which it is used together form multidimensional, multi feedback control system, and software quality is part of the quality of the systems behavior. We present here a scheme of that system and discuss the known software quality from that point of view. Keywords: software quality, perspective, quality models. ACM Classification Keywords: A.0 General Literature - Conference proceedings

2 2 Latchezar Tomov Introduction In order to control software quality we need to be able to measure it. In order to measure it, we need to understand it. In order to understand it we need to define it. But why do we need to focus on quality? In [Deming, 2000] is explained how focusing on quality improvement leads to simultaneous increase of quality and decrease of costs via eliminating rework, staff attrition and litigation, while focus on reducing cost actually leads to increasing them. In this paper existing definitions and perspectives on quality will be analyzed to show their lack of completeness and initial proposal for new definition will be made. Specific for the Deming s approach is the accent on system s view of manufacturing which is absent in definitions of quality. Software quality definitions and perspectives In order to control software quality we need to be able to measure it. In order to measure it, we need to understand it. In order to understand it Ie need to define it. In this paper existing definitions and perspectives on quality will be analyzed to show their lack of completeness and initial proposal for new definition will be made. Some of the following definitions are viewed in [Tripathi, 2014] 1. Definitions in technical standards. "a The totality of features and characteristics of a software product that bear on its ability to satisfy given needs: for example, conform to specifications. b The degree to which software possesses a desired combination of attributes. c The degree to which a customer or user perceives that software meets his or her composite expectations. The Title of the Paper

3 CSECS 2015, June , Boston, MA USA 3 d The composite characteristics of software that determine the degree to which the software in use will meet the expectations of the customer". IEEE Standard (IEEE Std ) As an attribute, software quality is (1) the degree to which a system, component, or process meets specified requirements. (2) The degree to which a system, component, or process meets customer or user needs or expectations [IEEE IEEE Standard Glossary of Software Engineering Terminology]. "Quality comprises all characteristics and significant features of a product or an activity which relate to the satisfying of given requirements". German Industry Standard DIN Part 11 "Quality is the totality of features and characteristics of a product or a service that bears on its ability to satisfy the given needs". ANSI Standard (ANSI/ASQC A3/1978) 2. Definitions in scientific articles [Crosby,1979] The first erroneous assumption is that quality means goodness, or luxury or shininess. The word quality is often used to signify the relative worth of something in such phrases as good quality, bad quality and quality of life - which means different things to each and every person. As follows quality must be defined as conformance to requirements if we are to manage it. Consequently, the nonconformance detected is the absence of quality, quality problems become nonconformance problems, and quality becomes definable. [Juran,1988] The word quality has multiple meanings. Two of those meanings dominate the use of the word: 1) Quality consists of those The Title of the Section

4 4 Latchezar Tomov product features which meet the need of customers and thereby provide product satisfaction. 2) Quality consists of freedom from deficiencies. Nevertheless, in a handbook such as this it is most convenient to standardize on a short definition of the word quality as fitness for use. [Ishikawa, 1985] We engage in quality control in order to manufacture products with the quality which can satisfy the requirements of consumers. The mere fact of meeting national standards or specifications is not the answer, it is simply insufficient. International standards established by the International Organization for Standardization (ISO) or the International Electro technical Commission (IEC) are not perfect. They contain many shortcomings. Consumers may not be satisfied with a product which meets these standards. We must also keep in mind that consumer requirements change from year to year and even frequently updated standards cannot keep the pace with consumer requirements. How one interprets the term quality is important. Narrowly interpreted, quality means quality of products. Broadly interpreted, quality means quality of product, service, information, processes, people, systems etc. [Shewhart, 1931] There are two common aspects of quality: One of them has to do with the consideration of the quality of a thing as an objective reality independent of the existence of man. The other has to do with what we think, feel or sense as a result of the objective reality. In other word, there is a subjective side of quality. [Feigenbaum, 1983] Quality is a customer determination, not an engineer s determination, not a marketing determination, nor a general management determination. It is based on upon the customer s actual experience with the product or service, measured against his or her requirements stated or unstated, conscious or merely sensed, technically operational or entirely subjective and always representing a moving target in a competitive market. Product and service quality can be defined as: The total composite product and service characteristics of marketing, engineering, manufacture and maintenance though witch the product and service in use will meet the expectations of the customer. The Title of the Paper

5 CSECS 2015, June , Boston, MA USA 5 Quality perspectives -[Kitchenham and Pfleeger, 1996] define set of five perspectives on software quality The transcendental view sees quality as something that can be recognized but not defined. The user view sees quality as fitness for purpose. The manufacturing view sees quality as conformance to specification The product view sees quality as tied to inherent characteristics of the product The value-based view sees quality as dependent on the amount a customer is willing to pay for it The two main themes in all of the definitions are a) fitness for purpose and b) conformance to specifications. They do not guarantee the continuous proper work of the software. Specifications themselves can be incomplete or misleading and even if they aren t, product characteristics do not guarantee good work for every context of use. Users have expectations that are subjective and vary in time as explained by Ishikawa. In ideal setting, meeting them perfectly still do not guarantee work because of the subjectivity and the context of use. Even if we look to the all five perspectives on quality in [Kitchenham and Pfleeger,1996] we see the two major definitions objective characteristics of the product and subjective user view, value based view and indefinable transcendental view. As Deming have shown, we need to think for manufacturing not as bits and pieces, but as a system. Systematic approach to manufacturing has lead Japan on expansion in 20 th century and Deming prize was created for the managers who use it. We believe we need the same approach in defining quality. Defining the system Software is produced by companies using special processes like CMMI to satisfy users who apply it to control some process that impacts the environment as shown on Fig.1. The Title of the Section

6 6 Latchezar Tomov Figure 1 The software system The development process itself is instrumental in improving or maintaining quality of the products and is subject of development like the software. The software company has feedbacks from the users for whom it produces and who pay for the product, but it also has feedbacks from the environment which is impacted by the process which is controlled by the software. Software for example can be some part of system for controlling nuclear plant. The user of the software can be private company, and the environment can be the global set of all people if there is malfunction. In this case the user may want software which will just pass regulations and will not be expensive while the software company wants it to conform to their standards and pass regulations. It may still not be enough to guarantee security and in this case the impact of every malfunction can be enormous. The feedback from such malfunction can lead to economical and law problems for the private company. One of the main problems with system with two feedbacks is that it is harder to control both user satisfaction and environment response. The described system is dynamic, e.g. the company needs to make continuous efforts to maintain The Title of the Paper

7 CSECS 2015, June , Boston, MA USA 7 equilibrium with the changing user requirements and the response of the environment to the controlled by the software process. Environment For companies, operating in market economy, this is a complex subsystem, consisting of the state, the competition, people that are affected by the use of the software, like clients of the nuclear plant, and people that could be affected. Some elements are hostile by definition the competition, the state. Hostile in this context means that impose obstacles which the company needs to overcome to pass state regulations for its own system employees, development process,; to overcome the competition in the race for the clients. Environment has also random components, related to global economy and nature which can be either hostile or friendly and for which the company has to take control measures, to minimize the product quality sensitivity to them. System quality perspective There is no guarantee that even if we satisfy all five perspectives on quality we will achieve safe, continuous work of the system which means all of the following: Stable profits for the company Stable satisfaction level of the users Reliable and stable work of the software The market-driven user satisfaction perspective wants to achieve profits in short term for the company via giving the users what they want. Here, the ethical component is missing. What the user wants and what will work safely are different things in general because of the market considerations since users are often subjects on the market, using the software to obtain profit. Moreover as [Deming 2000] working for short term profits undermines long term ones. This is because of the nature of The Title of the Section

8 8 Latchezar Tomov the system described. Short term profit often leads to sacrificing quality which leads to negative impact on the environment which propagates negative feedback to the users and the software company. If the user expectations are met and the product conforms to specifications but the system tend to work in negative direction (lowering profits, damaging the environment, etc) then the two basic definitions are not enough. The system quality perspective is simple: The systems view sees software quality as part of the system quality. High quality software is such for which the system in which is participating is achieved high quality System quality is the quality of work of the whole system for which there is continuous improvement of all system variables, including software company profits, user satisfaction and profits, the quality of the controlled process and the impact of the environment. System quality includes the quality of all subsystems the software company subsystem, the user company subsystem, the multitude of subsystems in the environment. If the developers or the users are unhappy, this affects system quality in time. Software quality definitions Software quality needs not to have radically different definitions than in the other perspectives. Quality is fitness for purpose, but the purpose is qualified as the purpose of the system. Def. Software quality is fitness for the purpose of the system that includes users, controlled processes, environment, software company subsystems and all other relevant systems and subsystems that interact The Title of the Paper

9 CSECS 2015, June , Boston, MA USA 9 with the software. The purpose of the system is to control certain process continuously in time which means to bring profits and satisfy the company and the users and to protect the environment in order to receive positive feedback from it. The work of the system should lead to positive feedback in order for the system to preserve equilibrium. Here we use the term in the emotional context in which people understand positive and negative while in mathematical control theory negative feedbacks stabilize the system. Conclusion In this paper we discuss the way quality is viewed from different perspective and their shortcoming. We propose system quality perspective and definition of quality. We intend to propose quality models and metric in future articles, based on system view. Bibliography [Crossby, 1979] P.B.Crosby, Quality is free : the art of making quality certain, New York : McGraw-Hill, [Deming, 2000] W.E.Deming. Out of the Crisis. The MIT Press; Reprint edition (August 11, 2000). ISBN-13: [Feigenbaum, 1983] A.V.Feigenbaum, Total quality control, McGraw-Hill, [Juran, 1988] J.M.Juran, Juran's Quality Control Handbook, McGraw-Hill, [Hoyer et al. 2001] R.W.Hoyer,. and B.B.Y. Hoyer. "What is quality?",quality Progress, no. 7, pp , [Ishikawa, 1985] K.Ishikawa, What is total quality control? : the Japanese way, Prentice-Hall, [Kitchenham and Pfleeger,1996] B.Kitchenham,S.L.Pfleeger. Software Quality: The Elusive Target, IEEE Software, Vol.13, Issue 1., 1996, pp [Shewhart, 1931] W.A.Shewhart, Economic control of quality of manufactured product, Van Nostrand, The Title of the Section

10 10 Latchezar Tomov [Tripathi, 2014] S.Tripathi A Survey on Quality Perspective and Software Quality Models, IOSR Journal of Computer Engineering, p- ISSN: Volume 16, Issue 2, Ver. VI (Mar-Apr. 2014), PP Authors' Information Your photo here: Height: 2,58 cm Width: 1,84 cm Latchezar Tomov, PhD, assistant professor in Deprartment of Informatics, New Bulgarian University, Sofia, luchesart@gmail.com.. Major Fields of Scientific Research: control theory, software engineering, software project management Your photo here: Height: 2,58 cm Width: 1,84 cm Valentina Ivanova, PhD, head assistant professor in Deprartment of Informatics, New Bulgarian University, Sofia, v.ivanova@nbu.bg. Major Fields of Scientific Research: e-leadership, software engineering, software project management The Title of the Paper