BS ISO IEC 15026-2-2011 Systems and software engineering Systems and software assurance Assurance case《系统和软件工程 系统和软件保证 保证案件》.pdf

1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication BS ISO/IEC 15026-2:2011 Systems and software engineering Systems and software assurance Part 2: Assurance caseBS ISO/IEC 15026-2:2011 BRITISH STANDARD National foreword This B

2、ritish Standard is the UK implementation of ISO/IEC 15026-2:2011. The UK participation in its preparation was entrusted to Technical Committee IST/15, Software and systems engineering. A list of organizations represented on this committee can be obtained on request to its secretary. This publication

3、 does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 70311 9 ICS 35.080 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the autho

4、rity of the Standards Policy and Strategy Committee on 31 March 2011. Amendments issued since publication Date Text affectedBS ISO/IEC 15026-2:2011Reference number ISO/IEC 15026-2:2011(E) ISO/IEC 2011INTERNATIONAL STANDARD ISO/IEC 15026-2 First edition 2011-02-15 Systems and software engineering Sys

5、tems and software assurance Part 2: Assurance case Ingnierie du logiciel et des systmes Assurance du logiciel et des systmes Partie 2: Cas dassurance BS ISO/IEC 15026-2:2011 ISO/IEC 15026-2:2011(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing polic

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9、ublication 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 ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 G

10、eneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2011 All rights reservedBS ISO/IEC 15026-2:2011 ISO/IEC 15026-2:2011(E) ISO/IEC 2011 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Conformanc

11、e.1 3 Normative references1 4 Terms and definitions .1 5 Use of this part of ISO/IEC 15026.1 6 Structure and contents of an assurance case .2 6.1 General .2 6.2 Overall structure3 6.3 Claims.5 6.3.1 Form of claim .5 6.3.2 Claim contents.5 6.3.3 Coverage of conditions.5 6.3.4 Justification of the cho

12、ice of top-level claims .5 6.4 Arguments6 6.4.1 Argument characteristics .6 6.4.2 Justification of arguments method of reasoning6 6.5 Evidence.6 6.5.1 Evidence contents.6 6.5.2 Associated information.6 6.5.3 Associated assumptions 6 6.6 Assumptions7 6.6.1 Form of Assumption .7 6.6.2 Assumption conte

13、nts7 6.6.3 Associated evidence.7 6.7 Justifications .7 6.8 Combining assurance cases7 7 Required outcomes of using Part 2 assurance case.7 7.1 Outcomes .7 7.2 Mapping to this part of ISO/IEC 15026 8 Bibliography9 BS ISO/IEC 15026-2:2011 ISO/IEC 15026-2:2011(E) iv ISO/IEC 2011 All rights reservedFore

14、word ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical

15、committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in

16、the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare Internatio

17、nal Standards. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of th

18、e elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC 15026-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 7, Software and systems engineeri

19、ng. ISO/IEC 15026 consists of the following parts, under the general title Systems and software engineering Systems and software assurance: Part 1: Concepts and vocabulary Technical Report Part 2: Assurance case System integrity levels and assurance in the life cycle will form the subjects of future

20、 parts. BS ISO/IEC 15026-2:2011 ISO/IEC 15026-2:2011(E) ISO/IEC 2011 All rights reserved vIntroduction The purpose of this part of ISO/IEC 15026 is to ensure the existence of types of assurance case content and restrictions on assurance case structure, thereby improving consistency and comparability

21、 among instances of assurance cases and facilitating stakeholder communications, engineering decisions, and other uses of assurance cases. Existing standards addressing different application areas and topics related to assurance cases might use differing terminology and concepts when addressing comm

22、on themes. This part of ISO/IEC 15026 is based on experience drawn from these many specialized standards and guidelines. It is applicable to any property of a system or product. NOTE It is intended that ISO/IEC TR 15026-1 will be transformed into an International Standard. In addition to concepts an

23、d terminology, ISO/IEC TR 15026-1 provides background and a list of related standards that could be useful in understanding and using this part of ISO/IEC 15026. Assurance cases are generally developed to support claims in areas such as safety, reliability, maintainability, human factors, operabilit

24、y, and security, although these assurance cases are often called by more specific names, e.g. safety case or reliability and maintainability (R transition, operations, and maintenance documentation; training; operator and user aids; data collection capabilities; and services included in or accompany

25、ing the system or product. Knowledge of these limitations allows avoidance and recognition of violations of relevant assumptions or the conditions related to the top-level claims. NOTE 4 The text often refers to a single assurance case or to a single top-level claim; however, a system or product may

26、 have multiple assurance cases, and an assurance case may have multiple top-level claims. 6 Structure and contents of an assurance case 6.1 General This part of ISO/IEC 15026s description of assurance case structure and contents uses the term “components” for the main parts of an assurance case and

27、describes the relationships among these components. The following general requirements apply: a) The components of an assurance case shall be unambiguous, identifiable, and accessible. BS ISO/IEC 15026-2:2011 ISO/IEC 15026-2:2011(E) ISO/IEC 2011 All rights reserved 3NOTE Ambiguity may be avoided by

28、associating a component with information on its context, such as: definitions of the terms used, the environment of the system or product, and the identities of entities responsible for a components development or maintenance. b) Each component shall be uniquely identified and shall be able to have

29、its origin identified, its history ascertained, and its integrity assured. c) For each component, the components contents, the information related to it, and the other components with which it has relationships shall be identifiable and accessible.“ NOTE For each component, its description and neede

30、d other components, e.g., evidence for claims and related information such as test case results, are identifiable and accessible. d) An assurance case shall contain the auxiliary contents required by ISO/IEC 15289 for this type of documentation. NOTE This part of ISO/IEC 15026 places no restrictions

31、 on how these auxiliary contents are included and no requirement that the assurance case be a separate document. 6.2 Overall structure The five principal components of an assurance case are claims, arguments, evidence, justifications, and assumptions. Figure 1 describes the structure of assurance ca

32、ses. It is not normative. Claims A claim is a proposition to be assured about the system of concern. It may be accompanied with auxiliary information such as the range of some date mentioned in the proposition or the uncertainty of the proposition. Justifications, Arguments, Evidence and Assurance C

33、ases Justifications, arguments, evidence and assurance cases are defined mutually recursively in this figure. Given a claim c, a justification j of c is a reason why c has been chosen. Comment: Therefore, a justification is defined relative to a claim c. An argument (defined below) is also defined r

34、elative to a claim, but it is different from justification because a justification is a reason for the choice of a claim, while an argument is a reason why a claim is true. Given a claim c and a set es of evidence, an argument that assures c using es is defined to be a reason why the truth of c is d

35、educed from the main part of evidence in the set es. Evidence is either a fact, a datum, an object, a claim or an assurance case. A claim is called an assumption if it appears in an assurance case as evidence. The main part of the evidence is defined according to the form of the evidence; if the evi

36、dence is either a fact, datum, object or a claim, its main part is itself; but if the evidence is an assurance case a 0 , its main part is the claim of a 0 . Comment: It will be clarified below in this figure that the evidence of an assurance case is used by an argument of that assurance case to ass

37、ure that its claim holds. Comment: A claim appearing as evidence is called an assumption because such evidence is a proposition without any reason why it is true. When a reason for its truth is provided, it is expected that an assurance case, whose argument is that reason, is constructed and provided as the evidence instead of providing only the claim as evidence.