1、National Standard of CanadaCAN/CSA-ISO/IEC TR 9126-2:04(ISO/IEC TR 9126-2:2003)Technical Report ISO/IEC TR 9126-2:2003 (first edition, 2003-07-01) has been adopted withoutmodification (IDT) as CSA Standard CAN/CSA-ISO/IEC TR 9126-2:04, which has been approved as a NationalStandard of Canada by the S
2、tandards Council of Canada.ISBN 1-55397-720-3 December 2004Reference numberISO/IEC TR 9126-2:2003(E)ISO/IEC 2003Software engineering Product quality Part 2: External metrics Gnie du logiciel Qualit des produits Partie 2: Mtrologie externe The Canadian Standards Association (CSA), under whose auspice
3、s this National Standard has been produced, was chartered in 1919 and accredited by the Standards Council of Canada to the National Standards system in 1973. It is a not-for-profit, nonstatutory, voluntary membership association engaged in standards development and certification activities. CSA stan
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10、rds Association5060 Spectrum Way, Suite 100Mississauga, Ontario, L4W 5N6CanadaThe Standards Council of Canada is the coordinating body of the National Standards system, a federation of independent, autonomous organizations working towards the further development and improvement of voluntary standard
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17、ponsibility of the users to judge its suitability for their particular purpose.Registered trade-mark of Canadian Standards AssociationCAN/CSA-ISO/IEC TR 9126-2:04 Software engineering Product quality Part 2: External metricsDecember 2004 Canadian Standards Association CSA/1CAN/CSA-ISO/IEC TR 9126-2:
18、04Software engineering Product quality Part 2: External metricsCSA PrefaceStandards development within the Information Technology sector is harmonized with international standards development. Through the CSA Technical Committee on Information Technology (TCIT), Canadians serve as the Canadian Advis
19、ory Committee (CAC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian National Committee of the IEC. Also, as a member of the International Telecommunication Union (ITU
20、), Canada participates in the International Telegraph and Telephone Consultative Committee (ITU-T).This Technical Report was reviewed by the CSA TCIT under the jurisdiction of the Strategic Steering Committee on Information Technology and deemed acceptable for use in Canada. (A committee membership
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24、m Way, Suite 100, Mississauga, Ontario, Canada L4W 5N61-800-463-6727 416-747-4044www.csa.caReference numberISO/IEC TR 9126-2:2003(E)ISO/IEC 2003TECHNICAL REPORT ISO/IECTR9126-2First edition2003-07-01Software engineering Product quality Part 2: External metrics Gnie du logiciel Qualit des produits Pa
25、rtie 2: Mtrologie externe ISO/IEC TR 9126-2:2003(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the compute
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28、ntral Secretariat at the address given below. ISO/IEC 2003 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either
29、 ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org ii ISO/IEC 2003 All rights reservedISO/IEC TR 9126-2:2003(E) ISO/IEC 2003 All rig
30、hts reserved iiiContents Page Foreword vi Introduction vii 1 Scope. 1 2 Conformance 2 3 Normative references. 2 4 Terms and definitions 2 5 Abbreviated terms 2 6 Use of software quality metrics 3 7 How to read and use the metrics tables 4 8 Metrics tables 4 8.1 Functionality metrics. 5 8.1.1 Suitabi
31、lity metrics 5 8.1.2 Accuracy metrics . 5 8.1.3 Interoperability metrics 5 8.1.4 Security metrics 5 8.1.5 Functionality compliance metrics 6 8.2 Reliability metrics 14 8.2.1 Maturity metrics 14 8.2.2 Fault tolerance metrics 14 8.2.3 Recoverability metrics . 14 8.2.4 Reliability compliance metrics 14
32、 8.3 Usability metrics 25 8.3.1 Understandability metrics . 25 8.3.2 Learnability metrics . 25 8.3.3 Operability metrics. 26 8.3.4 Attractiveness metrics. 26 8.3.5 Usability compliance metrics 26 8.4 Efficiency metrics 41 8.4.1 Time behaviour metrics . 41 8.4.2 Resource utilization metrics . 41 8.4.
33、3 Efficiency compliance metrics 41 8.5 Maintainability metrics 52 8.5.1 Analysability metrics . 52 8.5.2 Changeability metrics 52 8.5.3 Stability metrics 52 8.5.4 Testability metrics 52 8.5.5 Maintainability compliance metrics 52 8.6 Portability metrics 60 8.6.1 Adaptability metrics . 60 ISO/IEC TR
34、9126-2:2003(E) iv ISO/IEC 2003 All rights reserved8.6.2 Installability metrics .60 8.6.3 Co-existence metrics60 8.6.4 Replaceability metrics60 8.6.5 Portability compliance metrics60 Annex A (informative) Considerations When Using Metrics68 A.1 Interpretation of measures68 A.1.1 Potential differences
35、 between test and operational contexts of use68 A.1.2 Issues affecting validity of results69 A.1.3 Balance of measurement resources .69 A.1.4 Correctness of specification69 A.2 Validation of Metrics 69 A.2.1 Desirable Properties for Metrics .69 A.2.2 Demonstrating the Validity of Metrics 70 A.3 Use
36、of metrics for estimation (judgement) and prediction (forecast) 71 A.3.1 Quality characteristics prediction by current data .71 A.3.2 Current quality characteristics estimation on current facts 71 A.4 Detecting deviations and anomalies in quality problem prone components 72 A.5 Displaying measuremen
37、t results72 Annex B (informative) Use of Quality in Use, External type 2, when the subject is still under technical development or where for any other reason there is the future but not immediate possibility of an agreement on an International Standard; type 3, when the joint technical committee has
38、 collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example). Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they can be transformed into International Standards
39、. Technical Reports of type 3 do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held respons
40、ible for identifying any or all such patent rights. ISO/IEC TR 9126-2:2003, which is a Technical Report of type 2, was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 7, Software and system engineering. This document is being issued in the Technical Repor
41、t (type 2) series of publications (according to the Procedures for the technical work of ISO/IEC JTC 1) as a “prospective standard for provisional application” in the field of external metrics for quantitatively measuring external software because there is an urgent need for guidance on how standard
42、s in this field should be used to meet an identified need. This document is not to be regarded as an “International Standard”. It is proposed for provisional application so that information and experience of its use in practice may be gathered. Comments on the content of this document should be sent
43、 to the ISO Central Secretariat. A review of this Technical Report (type 2) will be carried out not later than three years after its publication with the options of: extension for another three years; conversion into an International Standard; or withdrawal. ISO/IEC 9126 consists of the following pa
44、rts, under the general title Software engineering Product quality: Part 1: Quality model Part 2: External metrics Part 3: Internal metrics Part 4: Quality in use metrics ISO/IEC TR 9126-2:2003(E) ISO/IEC 2003 All rights reserved viiIntroduction This Technical Report provides external metrics for mea
45、suring attributes of six external quality characteristics defined in ISO/IEC 9126-1. The metrics listed in this Technical Report are not intended to be an exhaustive set. Developers, evaluators, quality managers and acquirers may select metrics from this Technical Report for defining requirements, e
46、valuating software products, measuring quality aspects and other purposes. They may also modify the metrics or use metrics which are not included here. This Technical Report is applicable to any kind of software product, although each of the metrics is not always applicable to every kind of software
47、 product. ISO/IEC 9126-1 defines terms for the software quality characteristics and how these characteristics are decomposed into subcharacteristics. ISO/IEC 9126-1, however, does not describe how any of these subcharacteristics could be measured. ISO/IEC TR 9126-2 defines external metrics, ISO/IEC
48、TR 9126-3 defines internal metrics and ISO/IEC 9126-4 defines quality in use metrics, for measurement of the characteristics or the subcharacteristics. Internal metrics measure the software itself, external metrics measure the behaviour of the computer-based system that includes the software, and qu
49、ality in use metrics measure the effects of using the software in a specific context of use. This Technical Report is intended to be used together with ISO/IEC 9126-1. It is strongly recommended to read ISO/IEC 14598-1 and ISO/IEC 9126-1, prior to using this Technical Report, particularly if the reader is not familiar with the use of software metrics for product specification and evaluation. Clauses 1 to 7 and Annexes A to D are common to ISO/IEC TR 9126-2, ISO/IEC TR 9126-3, and ISO/IEC 9126-4. TECHNICAL REPOR
