1、 International Telecommunication Union ITU-T Z.450TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2008) SERIES Z: LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS Quality Quality aspects of protocol-related Recommendations Quality aspects of protocol-related Recommendations R
2、ecommendation ITU-T Z.450 ITU-T Z-SERIES RECOMMENDATIONS LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS FORMAL DESCRIPTION TECHNIQUES (FDT) Specification and Description Language (SDL) Z.100Z.109 Application of formal description techniques Z.110Z.119 Message Sequence Chart (MS
3、C) Z.120Z.129 Extended Object Definition Language (eODL) Z.130Z.139 User Requirements Notation (URN) Z.150Z.159 Testing and Test Control Notation (TTCN) Z.160Z.179 PROGRAMMING LANGUAGES CHILL: The ITU-T high level language Z.200Z.209 MAN-MACHINE LANGUAGE General principles Z.300Z.309 Basic syntax an
4、d dialogue procedures Z.310Z.319 Extended MML for visual display terminals Z.320Z.329 Specification of the man-machine interface Z.330Z.349 Data-oriented human-machine interfaces Z.350Z.359 Human-machine interfaces for the management of telecommunications networks Z.360Z.379 QUALITY Quality of telec
5、ommunication software Z.400Z.409 Quality aspects of protocol-related Recommendations Z.450Z.459 METHODS Methods for validation and testing Z.500Z.519 MIDDLEWARE Processing environment architectures Z.600Z.609 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Z.450 (1
6、1/2008) i Recommendation ITU-T Z.450 Quality aspects of protocol-related Recommendations Summary Recommendation ITU-T Z.450 provides guidelines on the quality aspects of protocol-related ITU-T Recommendations with the objective of: 1) improving the quality of protocol-related Recommendations; and 2)
7、 helping to improve the interoperability of products based on these Recommendations. In order to encourage the widest possible use of ITU-T protocol-related Recommendations, it is important that these Recommendations are of the highest possible quality. Several aspects of quality that play an import
8、ant role for the users of these ITU-T Recommendations have been selected for this purpose. These are: readability, completeness, correctness, consistency, unambiguity, implementability and testability. Annex A contains a quality checklist to identify the level of compliance of a Recommendation with
9、the quality aspects. Source Recommendation ITU-T Z.450 was approved on 13 November 2008 by ITU-T Study Group 17 (2009-2012) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T Z.450 (11/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the
10、 field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standa
11、rdizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is cov
12、ered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indi
13、cate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved
14、 when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PRO
15、PERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asser
16、ted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned t
17、hat this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Re
18、c. ITU-T Z.450 (11/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations 2 5 Developing high-quality Recommendations 3 5.1 Overview of the quality aspects . 3 5.2 Upfront identification . 4 5.3 Formal description techniques 4 5.4 Overview of the process . 4 6 Quality chec
19、ks 5 7 Specific guidelines 5 7.1 Readability 5 7.2 Completeness of a set of Recommendations 6 7.3 Correctness . 6 7.4 Consistency. 7 7.5 Unambiguity. 7 7.6 Implementability. 7 7.7 Testability. 7 8 Use of tools in developing Recommendations . 7 8.1 Early error detection. 7 8.2 Timely Recommendations
20、7 8.3 Lower cost 8 Annex A Quality checklist for protocol-related Recommendations. 9 A.1 General checklist 9 A.2 Specific checklist 9 A.3 Specific questions. 10 Bibliography. 12 iv Rec. ITU-T Z.450 (11/2008) Introduction Following WTSC-96 endorsement of the importance of quality in ITU-T Recommendat
21、ions, TSAG formed a Correspondence Group to develop a guideline document entitled Guidelines on quality aspects of protocol-related Recommendations. At the TSAG meeting in September 1998, the work of the Correspondence Group was approved as Supplement 1 to the A-series of ITU-T Recommendations. In t
22、he 2001-2004 study period, Study Group (SG) 10 contributed to the work of the TSAG Correspondence Group and subsequently approved a new Question and developed Recommendation ITU-T Z.450 based on Supplement 1. This Recommendation is the result of that work revised to reflect changes up to the end of
23、the 2005-2008 Study Period. All study groups should use this Recommendation when developing new protocol standards or evaluating existing ones. Rec. ITU-T Z.450 (11/2008) 1 Recommendation ITU-T Z.450 Quality aspects of protocol-related Recommendations 1 Scope This Recommendation covers the readabili
24、ty, correctness, consistency, unambiguity, implementability and testability aspects of quality of protocol-related Recommendations and specifies a process that can assist in the development of higher-quality Recommendations. 2 References The following ITU-T Recommendations and other references conta
25、in provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the
26、 possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a R
27、ecommendation. ITU-T Z.110 Recommendation ITU-T Z.110 (2008), Criteria for use of formal description techniques by ITU-T. 3 Definitions This Recommendation defines the following terms: 3.1 specification and description language (SDL): Internationally standardized formal language for specifying and d
28、escribing real-time systems. 3.2 message sequence charts (MSC): Internationally standardized language for describing sequences of messages interchanged between system components and their environment. 3.3 abstract test suite (ATS): A test suite composed of abstract test cases. 3.4 abstract test case
29、: A complete and independent specification of the actions required to achieve a specific test purpose, defined at the level of abstraction of a particular abstract test method, starting in a stable testing state and ending in a stable testing state. This specification may involve one or more consecu
30、tive or concurrent connections. 3.5 abstract test method: The description of how an implementation under test is to be tested, given an appropriate level of abstraction to make the description independent of any particular realization of a means of testing, but with enough detail to enable abstract
31、test cases to be specified for this test method. 3.6 executable test suite (ETS): A test suite composed of executable test cases. 3.7 executable test case: A realization of an abstract test case. 3.8 tree and tabular combined notation (TTCN-2): A standardized notation for specifying conformance test
32、 suites in a manner that is independent of test methods, layered software architectures or protocols and which reflects the abstract testing methodology defined in b-ITU-T X.290 and b-ITU-T X.291. NOTE TTCN-2 replaced the version of tree and tabular combined notation previously known as TTCN-1. 3.9
33、testing and test control notation (TTCN-3): A new version of the test notation has a programming language-like appearance and was designed for many kinds of testing such as interoperability testing, robustness testing, regression testing, system testing and integration testing 2 Rec. ITU-T Z.450 (11
34、/2008) and for various emerging testing application areas. TTCN-3 retains the proven features of TTCN-2 but includes many new features for more efficient testing. TTCN-3 core language is defined in b-ITU-T Z.161 and the related aspects of TTCN-3 are defined in b-ITU-T Z.162 to b-ITU-T Z.170. 3.10 us
35、er requirements notation (URN): A high-level requirements notation that consists of two complementary languages, goal-oriented requirement language (GRL) and use case maps (UCM), which serve to cover initial phases of requirements elicitation, analysis, and validation with goals and scenarios. 3.11
36、validation: A process of checking a specification to ensure that it is syntactically and semantically correct and represents the intended behaviour. 3.12 conformance clause: A part of a standard or Recommendation which identifies what in the standard or Recommendation should be met in order to confo
37、rm to the standard or Recommendation. 3.13 specification: Prescription of the design of an aspect of a product or a set of products. 3.14 protocol implementation conformance statement (PICS): A statement made by the supplier of an implementation or system claimed to conform to a given specification,
38、 stating which capabilities have been implemented. 3.15 protocol implementation extra information for testing (PIXIT): A statement made by the supplier or an implementer of an IUT which contains or references all of the information (in addition to that given in PICS) related to the IUT and its testi
39、ng environment, which will enable the test laboratory to run an appropriate test suite against the IUT. 3.16 test tool: Hardware and/or software, excluding the test suite itself, used to carry out or assist in carrying out the testing required. 3.17 means of testing (MOT): Hardware and/or software,
40、and the procedures for its use, including the executable test suite itself, used to carry out the testing required. 3.18 implementation under test (IUT): An implementation of one or more requirements specifications, being that part of a system, which is to be studied by testing. 3.19 interoperabilit
41、y testing: Testing to assess the ability of two or more systems to exchange information and to make mutual use of the information that has been exchanged. 3.20 reference implementation: An implementation of one or more standards or specifications, against which a means of testing and test tools for
42、those standards or specifications are tested for the purpose of validation of those means of testing or test tools. 4 Abbreviations This Recommendation uses the following abbreviations: ASN.1 Abstract Syntax Notation One ATS Abstract Test Suite ETS Executable Test Suite FD Formal Definition FDT Form
43、al Description Technique GRL Goal-oriented Requirement Language ICS Implementation Conformance Statement IUT Implementation Under Test Rec. ITU-T Z.450 (11/2008) 3 IXIT Implementation eXtra Information for Testing MOT Means of Testing MSC Message Sequence Chart PICS Protocol Implementation Conforman
44、ce Statement PIXIT Protocol Implementation eXtra Information for Testing SDL Specification and Description Language TTCN-1 Tree and Tabular Combined Notation version 1 TTCN-2 Tree and Tabular Combined Notation version 2 TTCN-3 Testing and Test Control Notation version 3 UCM Use Case Map URN User Req
45、uirements Notation 5 Developing high-quality Recommendations 5.1 Overview of the quality aspects In preparing new Recommendations or making an assessment of the quality of existing Recommendations, the following aspects should be considered: Readability This requires that a Recommendation is well-st
46、ructured and can be easily read and understood. This implies good use of natural and formal languages with adequate use of figures, examples and references. Recommendations should be written in accordance with the appropriate style guide (the ITU English Language Style Guide if the natural language
47、is English). Completeness A protocol-related Recommendation should be complete in the sense that it includes all parts necessary for its implementation and, where necessary, testing. This includes clearly stated, precise and unambiguous specifications, that may be expressed in URN, SDL, MSC and ASN.
48、1. To facilitate testing, additional texts with Recommendation status are needed for completeness. These include: protocol requirements stated in point form, test suite structure and test purposes, the abstract test suite, the protocol implementation conformance statement proforma and the protocol i
49、mplementation extra information for testing proforma. Correctness Protocol-related Recommendations should be precise, unambiguous, error-free and should describe the intended behaviour. Protocols should be expressed using formal description techniques, so that use of the appropriate tools with simulation and validation capabilities will ensure that the description is valid and protocol behaviour is correct. Consistency Different parts of the Recommendation or a set of related Recommendations shall not contain contradictory information. If
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