1、 International Telecommunication Union ITU-T Z.110TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2008) SERIES Z: LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS Formal description techniques (FDT) Application of formal description techniques Criteria for use of formal descr
2、iption techniques by ITU-T Recommendation ITU-T Z.110 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.11
3、9 Message Sequence Chart (MSC) 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 principle
4、s Z.300Z.309 Basic syntax and 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.
5、379 QUALITY Quality of telecommunication 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 Recommen
6、dations. Rec. ITU-T Z.110 (11/2008) i Recommendation ITU-T Z.110 Criteria for use of formal description techniques by ITU-T Summary In view of the complexity and widespread use of Recommendations, it is imperative that adequate and appropriate description techniques and languages be used to ensure t
7、he required quality levels of Recommendations. The purpose of Recommendation ITU-T Z.110 is to guide the use of formal description techniques (FDTs) to ensure the quality of ITU-T Recommendations. Where special requirements for verification and validation exist, FDTs should be used. The effective us
8、e of FDTs requires phased procedures to introduce their use. This Recommendation states the procedures to accomplish this task. Effective use of FDTs implies the use of state-of-the-art tools. Source Recommendation ITU-T Z.110 was approved on 13 November 2008 by ITU-T Study Group 17 (2009-2012) unde
9、r Recommendation ITU-T A.8 procedure. ii Rec. ITU-T Z.110 (11/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Secto
10、r (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 standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every
11、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 covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview,
12、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 indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary
13、. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the nega
14、tive 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 PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the u
15、se of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendatio
16、n, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/w
17、ww.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. Rec. ITU-T Z.110 (11/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 1 3.1 Definitions 1 3.2 Abbreviat
18、ions . 1 4 FDTs . 2 4.1 Objectives of an FDT . 2 4.2 Benefits of an FDT . 2 4.3 Use of FDTs . 2 4.4 Support for FDTs 2 4.5 Criteria for the use of FDTs 3 5 Criteria for development and Recommendation of FDTs 3 6 Procedure for development of formal definitions. 3 7 Lead study group for languages and
19、description techniques 5 Bibliography. 6 iv Rec. ITU-T Z.110 (11/2008) Introduction Supplement 1 to ITU-T A-series Recommendations (09/1998), Guidelines on quality aspects of protocol related Recommendations, superseded by Recommendation ITU-T Z.450, states: “Guidelines on the use of FDTs are contai
20、ned in Recommendation ITU-T Z.110. It provides criteria for their use and should, therefore, be taken as a reference in conjunction with this Supplement. It is planned to extend the scope of Recommendation ITU-T Z.110 to cover a wider range of applications developed by groups such as the OMG.“ Resol
21、ution 4 on Conformity Assessment and Quality of Standards from the Joint Meeting of Global Standards Collaboration-5/RAST, Williamsburg, USA, 23-26 August 1999, concludes: a) “that the use of protocol specifications expressed in SDL in conjunction with the available SDL-based commercial software too
22、ls will in the end produce higher quality Recommendations; b) that approval of protocol Recommendations expressed in SDL will be achieved in a shorter time than approval of Recommendations written in natural language. and resolves: 1) to encourage ITU-T Study Groups to apply Supplement 1 to A-series
23、 Recommendations, Guidelines on quality aspects of protocol related Recommendations, when developing new protocol related recommendations; 2) to encourage ITU to provide editing and technical support for the development and maintenance of complex Recommendations; 3) to encourage companies that parti
24、cipate in GSC member organizations to make use of commercial SDL/TTCN tools in their reviews of draft Recommendations; 4) to encourage companies that participate in GSC member organizations to assist in the establishment of facilities for training in the use of formalized methodology and tools; and
25、5) to encourage GSC member organizations to participate in the development of the methodologies that they use in their standardization processes.“ The ITU-T formal description techniques are not restricted to specification of protocols, but are applicable to a much larger application area. NOTE 1 Th
26、e current versions of “SDL“ and “TTCN“ are SDL-2000 and either TTCN-2 or TTCN-3 (see References, Terms and definitions in this Recommendation). NOTE 2 Supplement 1 to ITU-T A-series Recommendations has been superseded by Recommendation ITU-T Z.450, Quality aspects of protocol-related Recommendations
27、. The content of a previous version of this Recommendation was also published as ISO Resolution ISO/IEC JTC/SC22 N145. The statement on precedence in case of several descriptions contained in the JTC 1 document is omitted in this Recommendation. Rec. ITU-T Z.110 (11/2008) 1 Recommendation ITU-T Z.11
28、0 Criteria for use of formal description techniques by ITU-T 1 Scope This Recommendation applies to the use of formal description techniques (FDTs) in ITU-T Recommendations. FDTs are intended to be used in the development, specification, implementation and verification of Recommendations (or parts t
29、hereof). 2 References None. 3 Terms and definitions 3.1 Definitions This Recommendation defines the following terms: 3.1.1 formal definition (FD): Part of a Recommendation based on the use of an FDT. 3.1.2 formal description technique (FDT): A specification technique based on a technical language us
30、ing rigorous and unambiguous rules both with respect to developing expressions in the language (formal syntax) and interpreting the meaning of these expressions (formal semantics). The main FDTs recommended by ITU-T are ASN.1 b-ITU-T X.680 series, TTCN-2 b-ITU-T X.292, TTCN-3 b-ITU-T Z.161 to b-ITU-
31、T Z.170, SDL-2000 b-ITU-T Z.100 to b-ITU-T Z.106, SDL-2000 combined with UML b-ITU-T Z.109, MSC b-ITU-T Z.120 and b-ITU-T Z.121 and URN b-ITU-T Z.150 and b-ITU-T Z.151. 3.1.3 natural language description: An example of an informal description technique using one of the languages used by ITU-T to pub
32、lish Recommendations. It may be supplemented with mathematical and other accepted notation, figures, etc. 3.2 Abbreviations This Recommendation uses the following abbreviations: ASN.1 Abstract Syntax Notation One FD Formal Definition FDT Formal Description Technique GSC Global Standards Collaboratio
33、n IDL Interface Description Language MSC Message Sequence Chart OMG Object Management Group RAST Radio Standardization SDL-2000 Specification and Description Language TTCN-2 Tree and Tabular Combined Notation version 2 TTCN-3 Testing and Test Control Notation version 3 2 Rec. ITU-T Z.110 (11/2008) U
34、ML Unified Modelling Language URN User Requirements Notation XML eXtensible Markup Language 4 FDTs 4.1 Objectives of an FDT The goal of an FDT is to permit precise and unambiguous specifications. FDTs are also intended to satisfy objectives such as: a basis for analysing specifications for correctne
35、ss, efficiency, etc. (by simulation, verification or systematic test derivation); a basis for determining completeness of specifications; a basis for validation of specifications against the requirements of the Recommendation; a basis for determining conformance of implementations to Recommendations
36、; a basis for determining consistency of specifications between Recommendations; a basis for implementation support. In some areas, more than one FDT may be needed to accomplish all objectives. 4.2 Benefits of an FDT The application of an FDT can provide benefits such as: improving the quality of Re
37、commendations, which in turn reduces maintenance costs to both ITU-T and to users of Recommendations; reducing dependency on the natural language to communicate technical concepts in a multilingual environment; supporting the validation of Recommendations and the easier generation of conformance tes
38、ts for Recommendations, which then makes it easier to test products; reducing development time and cost of implementations by using tools that are based on the properties of the FDTs; making the implementation easier, resulting in better products. 4.3 Use of FDTs FDTs are advanced techniques that ar
39、e widely used in industry. Significant investment in training and tools have been made by ITU-T members. There are limited resources for the development (rather than use) of FDTs. The development of FDTs tends to be a lengthy and costly task. Although there is expertise within the ITU-T Study Groups
40、 both to assess the technical merits of the formally described Recommendations and to reach consensus on them, this is also limited. 4.4 Support for FDTs The development and availability of tutorial and educational materials helps to provide widespread understanding of the complexities and capabilit
41、ies of FDTs. The benefits of using FDTs can only be assured after some training. Tools to support an FDT that is used in a Recommendation can ensure that many defects in draft Recommendations are removed before they are published, and that the FDT is used with the semantics defined in the FDT Recomm
42、endation. The use of electronic working methods enables Rec. ITU-T Z.110 (11/2008) 3 ITU-T members to analyse draft Recommendations and utilize approved Recommendations in their own preferred FDT tools. TSB continues, and plans to expand, its validation of formal description components of ITU-T Reco
43、mmendations: “For several years, the TSB has performed a compilation validation of ASN.1 and XML source code that forms an “electronic attachment“ to an ITU-T Recommendation, a service which has been the envy of some standard development organizations. TSB is responsible for managing the inventory o
44、f the Intellectual Property associated with this growing catalogue of “electronic attachments“.“ 4.5 Criteria for the use of FDTs The description techniques used within a Recommendation shall be decided by the study group responsible for the Recommendation taking into account the factors in clauses
45、4.1 to 4.4 and the procedure in clause 6. The primary criteria for the decision shall be the technical quality of the Recommendation. The description techniques listed in clause 3.1.2 shall be used for those parts of a Recommendation that can be described in this way. In some cases, other criteria s
46、uch as existing documentation and urgent market needs are sufficient to justify an alternative description approach. Where a Recommendation could use one of the techniques listed in clause 3.1.2, but a different technique or just natural language is used, the rationale for the choice taken shall be
47、provided, and preferably included in the Recommendation. 5 Criteria for development and Recommendation of FDTs It is important to avoid unnecessary proliferation of FDTs, because of the cost and difficulty of supporting many FDTs both for ITU-T and for its members. The following criteria shall be me
48、t before adopting a new FDT for use in ITU-T Recommendations: the need for the FDT shall be demonstrated; evidence that it is based on a significantly different model from that of an existing FDT shall be provided; the usefulness and capabilities of the FDT shall be demonstrated; there should be at
49、least two tools that adequately support the FDT available to any party on reasonable and non-discriminatory terms. When a significant modification to an existing FDT is considered, this shall be treated in basically the same way as a new FDT, regardless of whether the change is backwards compatible or not. The objectives are to keep both the number of FDTs low and each FDT itself stable to the benefit of all parties. Any adoptions of new FDTs or modifications of existing FDTs should be communicated to the lead study
