Corso di Laurea Magistrale in Ingegneria Informatica per la Gestione d aziendad

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1 Corso di Laurea Magistrale in Ingegneria Informatica per la Gestione d aziendad Gestione della Qualità-II parte La produzione del software: metodologie e standards a.a Docente: Gigliola Vaglini Lezioni 15,16 La qualità del software 1

2 Software Quality Fundamentals Software engineers are expected to share a commitment to software quality as part of their culture. Ethics can play a significant role in software quality, the culture, and the attitudes of software engineers. The IEEE Computer Society and the ACM [IEEE99] have developed a code of ethics and professional practice based on eight principles to help software engineers reinforce attitudes related to quality and to the independence of their work. 3 Cont. For any engineered product, there are many desired qualities relevant to a particular perspective of the product, to be discussed and determined at the time that the product requirements are set down. Quality characteristics may be required or not, or may be required to a greater or lesser degree, and trade-offs may be made among them. 4 2

3 Product quality and process quality Quality can be seen from the point of view of the resulting software product and from the point of view of the production process There are standard for both the aspects, even if to state the quality of software product is a bit dangerous. 5 Standard specifici di prodotto Esistono per alcune categorie di prodotti: compilatori protocolli di comunicazione 6 3

4 Primo modello di qualità Il primo modello (McCall 1977) si basava su tre usi di un prodotto sw: Da utente (si ha una vista esterna del sw) Da sviluppatore (si ha una vista interna del sw) Da controllore (si ha bisogno di scale e metodi di misura) 7 Modello attuale La necessità di uno standard di qualità porta alla introduzione dell ISO/IEC 9126 (prima versione 1991) An attempt to give a schema for defining the software product quality. 8 4

5 Il modello ISO L'approccio alla qualità della norma la qualità del processo contribuisce a migliorare la qualità del prodotto la qualità del prodotto contribuisce a migliorare la qualità in uso controllare e migliorare il processo è un mezzo per migliorare la qualità del prodotto valutare e migliorare la qualità del prodotto migliora la qualità in uso 10 5

6 Fa distinzione fra attributi che caratterizzano la qualità vista dall utente ed attributi che caratterizzano la qualità vista in produzione caratteristiche esterne caratteristiche interne Il modello ha tre livelli Caratteristiche Sottocaratteristiche Metriche Le caratteristiche esterne sono organizzate in 2 livelli le caratteristiche del secondo livello sono in relazione con quelle del primo in base ad una gerarchia che definisce i legami le caratteristiche del secondo livello sono anche in relazione con le caratteristiche interne 11 Product quality: : ISO 9126 Six basic characteristics are defined from the point of view of the user: Functionality Reliability Usability Efficiency Maintainability Portability 12 6

7 External characteristics and sub- characteristics 13 Quality evaluation Each sub-characteristic must be associated with a metric to be quantitatively evaluated 14 7

8 ISO 9126 (cont.) 15 Quality in use Quality in use: specific users through the software product are able to obtain specific objectives with effectiveness, productivity, safety and satisfaction in a specific operational environment It was introduced in the release

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12 23 Metriche per la manutenibilità 24 12

13 Internal characteristics Internal characteristics are 38 and are bind to the external sub-characteristics Completness Access control Informativeness Self-descriptiveness Instrumentability Expressiveness Data-commonality Self-containedness Communication-commonality commonality Well-equipmentness equipmentness Traceability Timeliness Robustness Integrity Modularity Simplicity Coherency Accessibility Uniformity Accuracy Hierarchieness Consistency Metaphorability Attractiveness Access audit Memorability Conciseness Choosability Guideability

14 Limiti dei modelli di qualità 27 Conclusioni 28 14

15 Conclusioni 29 Standard di processo 30 15

16 Process quality:iso The International Standard was published August 1, The following (17) countries participated in the development of the standard: Australia, Brazil,, Canada, Czech Republic, Denmark,, Finland, France, Germany, Ireland,, Italy, Japan, Korea,, The Netherlands, Spain, Sweden,, the United Kingdom, and the United States of America. 31 Architecture The architecture is built with a set of processes and interrelationships among these processes. Not only one process 32 16

17 Processes characteristics Modularity. The processes are modular; that is, they are maximally cohesive and minimally coupled to the practical extent feasible.. An individual process is dedicated to a unique function. Responsibility. A process is considered to be the responsibility of a party in the software life cycle.. In other words, each party has certain responsibilities. 33 Processes structure Each process is further designed in terms of its own constituent activities, each of which is further designed in terms of its constituent tasks. An activity under a process is a set of cohesive tasks. A task is a set of elementary or atomic actions.. A task consumes inputs (data, information, control) and produces outputs (data, information, control)

18 Process hierarchy 35 The model There are defined 17 Processes (+ 1 special process) 74 Activities 224 Tasks Each task is defined by requirements, selfdeclaration, recommendation, permissible action 36 18

19 Cont. The processes are grouped into three broad classes: primary; supporting; ; and organizational. Primary processes are the prime movers in the life cycle; they are acquisition, supply, development, operation,, and maintenance. Supporting processes are documentation, configuration management, quality assurance,, joint review, audit, verification, validation,, and problem resolution.. A supporting process supports another process in performing a specialized function. Organizational processes are management, infrastructure, improvement,, and training. An organization may employ an organizational process to establish,, control, and improve a life cycle process. 37 Processes hierarchy 38 19

20 The tailoring process Tailoring is deletion of non-applicable or in-effective processes, activities,, and tasks. A process, an activity,, or a task, that is not contained in the standard but is pertinent to a project, may be included in the agreement or contract. It should be noted that this process itself, however, cannot be tailored. 39 Primary processes Acquisition Process. This process defines the activities and tasks of the acquirer, that contractually acquires software product or service. The acquirer represents the needs and requirements of the users. Supply Process. This process contains the activities and tasks of the supplier.. The process may be initiated either by a decision to prepare a proposal to answer an acquirer's request for proposal or by signing and entering into a contract or an agreement with the acquirer to provide a software service. The process continues with the identification of procedures and resources needed to manage and assure the service

21 Primary processes Development Process. This process contains the activities and tasks of the developer of software. The development process is intended to be employed as a methodology for developing prototypes (or for studying the requirements and design of a product) ) or as a process to produce products. 41 Primary processes Operation Process. This process contains the activities and tasks of the operator of a software system. The process covers the operation of the software and operational support to users. Maintenance Process. The maintenance process contains the activities and tasks of the maintainer. This process is activated when a system undergoes modifications to code and associated documentation due to an error, or the need for an improvement or adaptation.. The objective is to modify an existing system while preserving its integrity. Whenever a software product needs modifications,, the development process is invoked to effect and complete the modifications properly.. The process ends with the retirement of the system

22 Support processes Documentation Process. This is a process for recording information produced by a life cycle process.. The process defines the activities, which plan, design, develop, edit, distribute and maintain those documents needed by all concerned such as managers, engineers and users of the system. 43 Support processes Configuration Management Process. This process is employed to identify, define,, and baseline software items in a system; to control modifications and releases of the items; to record and report the status of the items and modification requests; to ensure the completeness and correctness of the items; ; and to control storage, handling and delivery of the items

23 Support processes Verification Process. This process provides the evaluations related to verification of a product or service of a given activity. Verification determines whether the requirements for a system are complete and correct and that the outputs of an activity fulfill the requirements or conditions imposed on them in the previous activities.. The process covers verification of process, requirements,, design, code, integration,, and documentation. Validation Process. Validation determines whether the final, as-built system fulfills its specific intended use.. The extent of validation depends upon the project's criticality. 45 Support processes Joint Review Process. This process provides the framework for interactions between the reviewer and the reviewee. They may as well be the acquirer and the supplier respectively.. At a joint review,, the reviewee presents the status and products to the reviewer for comment (or approval)

24 Support processes Quality Assurance Process. This process provides the framework for independently and objectively assuring (the acquirer or the customer) ) of compliance of products or services with their contractual requirements and adherence to their established plans. To be unbiased,, software quality assurance is provided with the organizational freedom from persons directly responsible for developing the products or providing the services. Audit Process. This process provides the framework for formal, contractually established audits of a supplier's products or services.. At an audit,, the auditor assesses the auditee's products and activities with emphasis on compliance to requirements and plans.. An audit may well be conducted by the acquirer on the supplier. 47 Support processes Problem Resolution Process. This process provides the mechanism for instituting a closed-loop loop process for resolving problems and taking corrective actions to remove problems as they are detected.. In addition, the process requires identification and analysis of causes and reversal of trends in the reported problems.. The term "problem" includes non-conformance conformance

25 Organizational processes Management Process. This process defines the generic activities and tasks of the manager of a software life cycle process, such as the acquisition process, supply process, operation process, maintenance process,, or supporting process. Infrastructure Process. This process defines the activities needed for establishing and maintaining an underlying infrastructure for a life cycle process. This process has the following activities: Process implementation; ; Establishment of the infrastructure; and Maintenance of the infrastructure.. The infrastructure may include hardware, software, standards, tools, techniques,, and facilities. 49 Organizational processes Improvement Process. The standard provides the basic, top-level activities that an organization (that is, acquisition, supply, development, operation, maintenance,, or a supporting process) needs to assess, measure, control,, and improve its life cycle process. Training Process. This process may be used for identifying and making timely provision for acquiring or developing personnel resources and skills at the management and technical levels.. The process requires that a training plan be developed,, training material be generated,, and training be provided to the personnel in a timely manner

26 Processi primari Acquisition process 52 26

27 Acquisition process 53 Supply process 54 27

28 Development process 55 Operation process 56 28

29 Maintenance process 57 Esempio di analisi approfondita Esercizio: analisi dell attività dell acquisition process 58 29

30 59 Attività di Initiation 60 30

31 Attività di Initiation 61 Attività di Initiation 62 31

32 Attività di Request for proposal 63 Attività di Preparazione e update del contratto 64 32

33 Attività di Monitoraggio 65 Attività di Acceptance e completion 66 33

34 67 Cosa la norma non dice 68 34

35 Limiti della norma

36 La qualità totale Vari aspetti della qualità 72 36

37 La qualità totale Il concetto di Qualità è legato alla definizione di Qualità di Prodotto tramite: un accurata scelta delle materie prime un attenta fase di progettazione l utilizzo di maestranze esperte e qualificate tecniche di lavorazione orientate all eccellenza del risultato un severo ed efficace Controllo Qualità Il concetto di Qualità Totale o TQM (Total Quality Management) sta invece ad indicare che i concetti e le tecniche del Controllo Qualità devono essere estesi ed applicati a tutti i settori aziendali (CWQC = Company Wide Quality Control) con l obiettivo di raggiungere l eccellenza. La Qualità Totale rappresenta un potente strumento di gestione per raggiungere gli obiettivi dell organizzazione. Si passa da una visione a breve termine di Profitto prima di tutto ad una a più lungo termine di Qualità prima di tutto. 73 La qualità totale La qualità di un sistema software è largamente determinata dalla qualità del processo usato per la sua produzione e manutenzione. TQM pone al centro dell attenzione i processi, in particolare è l applicazione di metodi quantitativi e di risorse umane per il miglioramento: dei materiali e dei servizi usati da un organizzazione; di tutti i processi che si sviluppano nell organizzazione; del livello con il quale vengono soddisfatti i bisogni del cliente

38 Cambio di mentalità in azienda 75 La pianificazione della qualità 76 38

39 La pianificazione della qualità 77 L assicurazione della qualità 78 39

40 L assicurazione della qualità 79 Il controllo della qualità 80 40