Comparative Study of Software Quality Attributes in Perspective of Usability with Generalized Classification

Transcription

1 International Journal of ISSN Systems and Technologies Vol.3, No.2, pp IJST KLEF 2010 Comparative Study of Software Quality Attributes in Perspective of Usability with Generalized Classification K. Paithankar, Dr. M. Ingle Analyst, Shri Vaishnav Institute of Technology & Science, Indore School of Computer Science Information Technology, DAVV, Indore Abstract: Software quality attributes are the indispensable characteristics concerned with specific features or properties of software. Each quality attribute has unique contribution for successful software development. Not all the attributes impose the effect on software equally. With this notion, there exist many classifications of quality attributes in the literature. A new classification has been presented in view of usability as an essential feature of software in this paper. We observed that the change in environment affects the reference of characteristics and have different impact on software quality. Hence, there is a strong need to study the role, behavior and impact of software quality attributes with different perspectives. In this paper, we have compared usability based classification of quality attributes with generalized classification of quality attributes for studying the dynamic role of quality attributes in two different perspectives. It will lead to attain the optimum quality and will be useful for software developers to satisfy their needs in view of technological advancements and user-centered development. Introduction Software quality attributes are the multi-dimensional characteristics associated with multifaceted behavior of software. It has been clearly mentioned in literature that each quality attribute has pertaining to specific feature or property of software and has unique effect [[IEEE Std ; Boehm et al., 1976; Boehm, 1976; Fitzpatrick et al., 2004; ISO/IEC, 2001]. Hence, classification of quality attributes with different perspectives is required for the successful software development, thereby providing guidance and ease conform quality of product, process and service [Bansiya and Davis, 2002; Gousios et al, 2007]. It has been noticed that software quality attributes contribute equally for successful software development even though all sub characteristics do not equally affect software product and process [Boehm et al., 1976; Wakil et al., 2004; Yijun, 2005]. 241

2 K.Paithankar, Dr.M.Ingle Many classifications of quality attributes have been cited focusing on specific view. As per the view, the organization of quality attributes has modified. Further, it has been noted that with amendment in the quality organization the role and behavior of the attribute also changes as illustrated in Fig.-1. This dynamism may affect the quality of the software and its development. Hence, there exists a strong need to study the role, behavior and impact of software quality attributes in different perspectives. Classification as per ISO Standards Y classification X Generalized Quality Attribute Z Usability Oriented classification Fig.-1: Multidimensional dynamism of a quality attribute. Two classifications of quality attributes namely; generalized classification and usability based classification of quality attributes are mainly considered for this comparative study. These views of classification of software quality attributes are discussed in Section 2. This section deals with the presentation of generalized classification of quality attributes and classification of attributes in perspective of usability. In Section 3, the role and impact of various quality attributes has exhibited separately for different classifications in subsections as View-I and View-II. Finally, we conclude with benefits of changing behavior of quality attributes in Section

3 Comparative Study of Software 2. Views of Classification In this section, we present two quality attribute classifications to provide the details of specific view and organization. These views are discussed as follows: 2.1 Generalized Classification Generalized classification of quality attributes has been presented with systematic categorization of attributes in an integrated manner. It includes six major classes namely; Runtime attributes, Non-runtime attributes, Business Oriented attributes, Architecture Oriented attributes, Domain Specific attributes and Impact Oriented attributes along with their subattributes organized in columns as shown in Table-1. This classification provides an integrated view of quality attributes in correspondence with product and process [Paithankar and Ingle, 2008]. Run time class of quality attributes is strictly concerned with the execution time. These attributes are required to be measured at the time of system execution. At run time it is important to know about the working of the software and its behavior. It highlights on the fundamental process of transformation that software and hardware components of the system perform on inputs to produce outputs. For example, response of the system is considered to be and hence, at the time of user-system interaction the time and functional aspects of the software have to be thought about. Therefore, the quality attributes concern with the software in this manner has taken up in runtime class. Non-runtime attributes is another class of generalized quality classification that do not concerned with run time behavior of the system but play major role in determining quality in offline manner. Also, it has been noticed that the conformance of run time quality depends on the conformance of non-run time quality. It specifies criteria that can be used to judge the operation of a system and the way the system will do it. For example, software performance requirements, software external interface requirements, software design constraints are considered to be nonfunctional requirements of the system and are embodied in the static structure of the software system. One more class of this classification is Business attributes which are the non-software attributes that influence other software or non-software uality attributes. These attributes attempt to confirm quality in view of business policies. Business objectives are specific statements that give projections about growth or development 243

4 K.Paithankar, Dr.M.Ingle Table 1: Generalized Classification of Quality Attributes 1.0 Run Time 2.0 Non Run time 3.0 Business 4.0 Architecture 5.0 Domain Specific 1.1 Functionality Understandability Conciseness Consistency Clarity 1.2 Performance Utility Response timing Throughput behavior Timeliness 1.3 Security 1.4 Availability Reliability 1.5 Usability Learnability Efficiency Access Control Repeatability Unambiguity Validity Resilience Customizability Practicability Operability 1.6 Interoperability 1.7 Accessibility 1.8 Traceability 2.1 Manageability Modifiability Maintainability Flexibility 2.2 Portability Machine Independence System Independence Replaceability Installability Adaptability Data commonality 2.3 Reusability Representation Independence Application Independence Data Encapsulation Function Encapsulation Interfaceability 2.4 Integrity 2.5 Testability 2.6 Documentation 2.7 Completeness 2.8 Accuracy 3.1 Cost & Schedule 3.2 Economy 3.3 Marketability 3.4 Appropriateness of Organization 3.5 Localization 4.1 Conceptual integrity 4.2 Correctness 4.3 Structured 4.4 Scalability 4.5 Extensibility 4.6 Supportability 4.7 self- containedness 5.1 Sensitivity 5.2 Calibrability 5.3 Stability 6.0 Impact 6.1 simplicity 6.2 Maturity 6.3 Installability 6.4 Fault tolerance 6.5 Helpfulness 6.6 Affect 6.7 Communicativeness 6.8 Selfdescriptiveness 244

5 Comparative Study of Software to companies. These are the stated, measurable targets to achieve business aims. Architecture Oriented attributes is also non software attributes used to measure structural aspect of the system. There are many common ways of designing computer software modules and their communications. For example, Client-server, Database-centric architecture, Distributed computing, Event Driven Architecture, Peer-to-peer, Structured (module-based), Serviceoriented, Three-tier model are some of the available architectures may be used while system development. Domain Specific Attributes deals with the specific business and application domain. The objective of defining the domain is developing mass-customized products that reduce the costs, delays, and inflexibility characteristic of software and systems. Also it increases the ability to align business activities to the needs and produce solutions to cater the specific needs. The class of Impact Oriented attributes is mainly concerned with determining the overall effect of the system from users view point. User satisfaction is the primary goal of any software and has to be cultivated at conception stage of the system. Therefore, software has to be available in such a manner that influences the user without a need of redressal. Attributes and sub-attributes of each class are shown in Table Classification in Perspective of Usability Now a days, user satisfaction, comfort and convenience have become more important with increase in number of computer user, applications and variety of tasks performed. Therefore, it has become necessary to confirm wellness of use of the software to resolve difficulties while understanding instruction, manipulating parts or interpreting feedback. It has encouraged reviewing quality attributes classification in usability perspective. Instead of being solely a characteristic of the user interface, this classification has considered usability as a functional system of software where all the other quality attributes have been participating in quality of the software in perspective of usability [Paithankar and Ingle, 2009]. Thus, quality and usability have to be assured starting with conception till deployment of the system simultaneously. Hence, classification of quality attributes has been reviewed in usability perspective as shown in Table-2. The classification categorizes quality attributes in five main classes such as; Conceptual, 245

6 K.Paithankar, Dr.M.Ingle Design, Business, Conformance and Post implementation aspects of usable software [Paithankar and Ingle, 2009]]. Conceptual attributes are related to the fundamental block building of the system. Though, in traditional quality classification, usability is regarded as runtime system quality attribute, it should not to be considered as the implementation issue only. Hence, at conceptual level we have to provide those measures with which usability can be guaranteed. Usability is also concerned with the methods for improving ease-of-use during the design process. It has been noted that failure or success of the system is highly influenced by Table 2: Classification of Quality Attributes in Perspective of Usability 1.0 Conceptual 2.0 Design 3.0 Business 4.0 Conformance 5.0 Post Implementat 1.1 Practicability Accessibility Calibrabilty 1.2 Learnability Understandability Completeness Scalability 5.1 Resilience Manageability Maintainability Flexibility Testability 5.2 Adaptability 2.1 Operability Functionality Performance Interoperability Fault tolerance Simplicity 2.2 Efficiency Utility Response Time Throughput behaviour Sensibility Stability 2.3 Access Control Security Integrity Repeatability 2.4 Unambiguity Consistency Clarity Interoperability 3.1 Affect Consciseness Cost & schedule Economy Marketability Appropriateness of organization 3.2 Customizability Reusability Extensibility 4.1 Helpfulness Portability Localization Supportability 4.2 Validity Availability Reliability Accuracy Correctness 246

7 Comparative Study of Software the design of the system. The erroneous design tends to reduce successful implementation of system. Therefore, to continue usability considerations in process of development, design class of attributes has been provided. Business attributes represent the meta-attributes which influence other organizational attributes with inclusion of system existence. These attributes help to achieve the ultimate goal of any development i.e. to gain profit at organizational level and to improve in business etc. Another class of attributes in this classification is conformance attributes, which is identified as the measure of wellness of the software to meet the defined specifications. It verifies the criteria and definitions for the desired outcome. It is mainly concerned with the usability with conformance of concept and design to achieve business objectives and goal. It has been discussed that usability must be implemented as feature of the system. Though, usability consideration has to be carried from conception till implementation, attention must be given to verify the operational system in the context of user satisfaction with all the aspects of system working. Such usability verification must be carried after the field installation of the system. Hence, it is required to collect the feedback based on software performance and improvements can be made on the basis of this feedback information. This class is referred to be the post implementation attributes. 3. Proposed Work Quality being essential feature of the software, it is really important to observe the participation of quality attributes with their impact. Also, changes may be attempted for improvements to provide most appreciable and useable software. With this intent, we propose to illustrate the vigorous role of quality attributes in two perspectives of quality classification. The quality attributes underlined and highlighted in italic in Table-1 and Table-2 are considered to show the varying behavior. These are namely; 247

8 K.Paithankar, Dr.M.Ingle learnability, reliability, integrity, testability, stability and helpfulness. As shown in Table- 3, the role of these attributes with respect to the viewpoint is explained in View-I and View-II. 3.1 View-I The classes of generalized classification of quality attributes have been discussed in section 2.1. In this section, we analyze the behavior and role of aforesaid quality attributes as follows: Learnability - It is the measure of comfort to accomplish basic tasks while first time users encounter the system. In generalized classification it has identified as run time attribute and a subordinate attribute to usability as shown in Table-1. Run time attributes are strictly concerned with the execution of the system and measured at execution time. It highlights on the basic transformation process performed on inputs to produce outputs with software & hardware components. Therefore, Learnability along with its super class usability is considered to be a runtime attribute as shown in Table-1. Reliability - It is also included in set of runtime attribute as a subordinate attribute to availability. The justification of reliability being sub attribute of availability in run time class is due to the reason of its behavior as; it is the capability of the software to maintain its performance level under stated conditions and time period. It assures about the correctness of desired results and thus considered as sub-attribute of availability for the trusted use of the system. Integrity - It is identified to be a non-runtime attribute as shown in Table-1. Non-runtime attributes do not concern with runtime behavior, but specifies criteria that can be used to judge the manner of performing these operations. It focuses on non functional requirements of a system. Therefore, 248

9 Comparative Study of Software integrity being the ability to separately develop components and make them work together correctly is included in the classification as a non run-time attribute. Testability - It has given the great importance as it provides error handling capability to the system. Testing must be accomplished to assure the workable system prior to its execution. Hence, it has been considered to be non run time attribute of quality as referred in Table-1. Stability - It is the degree to which software can run over periods of time without crashing or otherwise malfunctioning. Basically, it has considered to be the domain specific attribute as illustrated in Table-1. Domain specific attributes deal with specific business and application domain. Its objective is to develop mass customized products to reduce cost, delays and inflexibility of the software. Hence, stability fulfills the criteria of this class of attributes for application area and the use of platform to build the system. Helpfulness - It is the measure of degree with which the system is ready to help users in all aspects of system s functionality. Software is said to be helpful if it possesses the characteristics of visibility and survivability. Impact oriented class conforms the availability of the software in such a manner that influences the user without a need of redressal. Thus, helpfulness has been identified as the impact oriented quality attribute in generalized classification as shown in Table View-II This section deals with the quality attributes in usability perspective. This classification has been presented in view of end user s benefits and satisfaction. Furthermore, in this classification usability has been observed to be a functional system with inclusion and impact of other attributes for its enumeration. The classification basically reviews all the quality attributes and sub-attributes in usability perspective as shown in Table-2. The same attributes explained in View-I are further referred to show the behavioral dynamism with the change in view point, as follows: 249

10 K.Paithankar, Dr.M.Ingle Learnability - While measures are defined to incorporate usability in software and software development, learnability has discussed as the issue of concept development phase. It now acts as a measure of comfort to accomplish the tasks while first time users encounter the system. The efforts have to put at conceptual stage of development, to identify users and their levels of understanding of the system. Further, it provides required support to realize the comfort of use by variety of users. Therefore, it justifies its existence in this class of attribute as shown in Table-2. Reliability - It is still defined as subordinate attribute of availability. As presented in Table- 2, it has been involved to measure validity property of usability, which is the attribute of conformance class in this classification. Conformance class is defined as the measure of wellness of the software to meet the defined specifications. It verifies the criteria and definitions for the desired outcome. Reliability proves itself to be the attribute of this class with modification of its definition as capability of the system to determine performance and functional requirement as and when desired. Integrity - To access the functionalities of the system, all of its components must be integrated to provide a complete system at any stage of the use. Usability is also concerned with the methods for improving ease-of-use during the design process. Integrity is the ability to make use of those components together which are separately developed. Hence, integrity has to be the design aspect of the system so as to provide modularity and ease of development. Therefore, integrity must be a design attribute while used in usability perspective as shown in Table-2. Testability - It is placed in post implementation class of quality attribute in this classification. The software has to be capable of handling errors more importantly during its use by end users. Developers have the knowledge of technological and operational features of the system. And therefore, act as administrative users of the system. Nevertheless, the end users are naive and need the support during its use. Therefore, testability stands to be a post implementation issue. 250

11 Comparative Study of Software Table - 3: Impact of quality attributes with different perspectives S. No. Quality Attributes View I (From generalized classification) 1 Learnability A run time attribute and subordinate attribute to usability. Measured at execution time. 2 Reliability A run time attribute and subordinate attribute to availability. Measured at execution time. 3 Integrity A non-run time attribute. Measured off line. 4 Testability A non-run time attribute. Measured off line. Usually refers to code and specification testing. 5 Stability A domain specific attribute. Deals with specific business and application domain consistency. 6 Helpfulness An impact oriented attribute. Measures influence of the software on users and used to improve the impact in all aspects of software functionality. View II (From usability Classification) A conceptual attribute. It has to be considered from conception of the system to get usable software. A conformance attribute and subordinate to availability. Refers to determine performance and functional requirement as and when desired. A design attribute and subordinate to access control attribute. Provide modularity and ease of development. A post implementation attribute and subordinate attribute to manageability. Act as revision element for usable software. A design attribute and subordinate attribute to efficiency. Measures consistency of design of a usable software to be used efficiently in construction. A conformance attribute to provide support, portability and localized application to users to conform the usage of the software. Stability - The results of analysis must be carefully incorporated in design to map specification to operational architecture of the system. The design is the core of system development. The software may collapse due to the incorrect and erroneous design. Design should handle uncertainties and changing requirements to support the construction phase. And hence, it has to be stable enough to support coding so that the software can be usable over periods of time with minimum chances of its crashing or malfunctioning. 251

12 K.Paithankar, Dr.M.Ingle Helpfulness - It is the ability to provide adequate help to guarantee the operationally feasible system. As helpfulness is the major and fundamental requirement of a usable system, it is considered to be a conformance class attribute. Satisfaction level of users tends to increase with increased help, in all dimensions of system usage. In case of difficulty to perform operations, user can easily seek for required guidance to continue with software. Therefore, change in behavior of this attribute towards usability can be observed in a defensible manner. 4. Conclusion In this paper, we have presented the dynamic role/ behavior of a quality attribute in different perspective based classification as shown in Fig.-2. Although, the definition of some quality attributes remain same (irrespective of the class in which these attributes lie) but due to the change in environment their behavior changes dynamically. As an effect, their impact plays an important role in the classification. This result will be useful for software developers to satisfy their need and thereby gaining the optimum quality. Also, it is possible to acquire usable software in view of technological up-gradation and user-centered development. CLA SS View-II View-I CLA SS A1 A2 A3 Class A1 A2 A3 CLASS Attributes Sub-Attributes CLAS S CLAS S CLAS S CLAS S Fig.-2: Dynamism of quality attributes with different perspectives. CLAS S CLAS S CLAS S 252

13 Comparative Study of Software References [1] IEEE Std ] IEEE Standard Glossary of Software Engineering Terminology In IEEE Standards Software Engineering, 1999 Edition, Volume1: Customer and Terminology Standards, IEEE Press, [2] Boehm et al., 1976] B. W. Boehm, J. R. Brown and M. Lip. Quantitative evaluation of software quality. Proceedings of the 2nd international conference on Software engineering, San Francisco, California, Pages: , [3] Boehm, 1976] B. W. Boehm. Characteristics of software quality. TRW series on software technology, Volume 1. [4] Fitzpatrick et al., 2004], R Fitzpatrick., P. Smith,. and B. O Shea. Software Quality Challenges. IEEE Proceedings of the Second Workshop on Software Quality at the 26th International Conference on Software Engineering (ICSE2004), Edinburgh, Scotland, [5] ISO/IEC, 2001] ISO/IEC International Standard. Software engineering Product quality Part 1: Quality model, International Organization for Standardization, [6] Bansiya and Davis, 2002] J. Bansiya,and C.G. Davis. A hierarchical model for objectoriented design quality assessment. IEEE Transactions on Software Engineering, Volume 28, Issue 1, pp. 4 17, January [7] Gousios et al, 2007] G. Gousios, V. Karakoidas, K. Stroggylos, P. Louridas, V. Vlachos and D. Spinellis. Software quality assessment of open source software. Current Trends in Informatics: 11th Panhellenic Conference on Informatics, PCI, Athens, volume A, pp , May

14 K.Paithankar, Dr.M.Ingle [8] Boehm et al., 1976] W. Boehm, J. R. Brown and M. B. Lipow. Quantitative evaluation of software quality. IEEE Proceedings of the 2nd International Conference on Software Engineering, pp , [9] Wakil et al., 2004] M. El Wakil, A. El Bastawissi, M. Boshra, and A. Fahmy. Object- Oriented Design Quality Models - A Survey and Comparison. 2nd International Conference on Informatics and Systems (INFOS04), March [10] Yijun, 2005] Yu Yijun. Lecture notes on Software Quality Measurements. Some materials are based on Fenton s book, [11] aithankar and Ingle, 2008] K. Paithankar and M. Ingle. Generalized classification of software quality attributes. Journal of Computer Science (JCS) Coimbatore, accepted [12] Paithankar and Ingle, 2009] K. Paithankar and M. Ingle. Reviewing Software Quality Attributes Classification in Perspective of Usability. Communicated to journal,