1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T Z.111 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2016) SERIES Z: LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS Formal description techniques (FDT) Application of formal description techniques
2、 Notations and guidelines for the definition of ITU-T languages Recommendation ITU-T Z.111 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 fo
3、rmal description techniques Z.110Z.119 Message Sequence Chart (MSC) Z.120Z.129 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 Basi
4、c 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.379 QUALITY Quali
5、ty 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 Recommendations. Rec. ITU
6、-T Z.111 (04/2016) i Recommendation ITU-T Z.111 Notations and guidelines for the definition of ITU-T languages Summary Recommendation ITU-T Z.111 provides meta-grammars for ITU-T Recommendations that define ITU-T languages in the ITU-T X.680 series and the ITU-T Z series of Recommendations on langua
7、ges for specification, implementation, modelling and testing. This allows the description of these meta-grammars that define the abstract or concrete grammar (syntax, constraints and semantics) of languages without having to repeat the meta-grammar (such as lexical naming rules, or the description o
8、f Backus-Naur Form syntax) as a preamble or annex to each language definition. This Recommendation draws common elements from the meta-grammars of various languages, covering issues such as common lexical rules, the use of a universal character set, and syntax and constraint description for language
9、s at both the abstract and concrete level. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T Z.111 2008-11-13 17 11.1002/1000/9621 2.0 ITU-T Z.111 2016-04-29 17 11.1002/1000/12862 Keywords ITU-T languages, meta-grammars, abstract grammar, concrete grammar, syntax, constraints,
10、 semantics. _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T Z.111 (04/2016) FOREWORD The International Telecommunication Un
11、ion (ITU) is the United Nations specialized agency in the 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
12、and issuing Recommendations on them with a view to standardizing 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 t
13、hese 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, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the ex
14、pression “Administration“ is used for conciseness to indicate 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 applic
15、ability) 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 negative equivalents are used to express requirements. The use of such words does not suggest that compliance with th
16、e Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU 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 applicabil
17、ity 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 Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement
18、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:/www.itu.int/ITU-T/ipr/. ITU 2016 All rights reserved. No part of this publication may be reproduced, by any means w
19、hatsoever, without the prior written permission of ITU. Rec. ITU-T Z.111 (04/2016) iii Table of Contents Page 1 Scope . 1 1.1 Objective . 1 1.2 Application . 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Conventions 2 5.1 Grammars . 2 5.2 Basic definitions . 2 5.3 Presentation
20、style 2 5.4 Metalanguages 5 Annex A Use of graphical meta-symbols . 20 Appendix I Mapping from the metamodel presentation to the textual presentation: High-level description 21 Bibliography. 23 iv Rec. ITU-T Z.111 (04/2016) Introduction Scope-objective: Notations and guidelines for the definition of
21、 formal languages are provided. Coverage: The main features of this Recommendation are notations for defining the abstract and concrete syntaxes of languages, and a common structure for defining languages. Applications: This Recommendation should be applied to new and possibly to revised formal lang
22、uage Recommendations. Status/Stability: The notation and guidelines given are stable and have been used on some of the existing language Recommendations, such as Recommendations the ITU-T Z.100 series and ITU-T Z.151. There is scope for further guidelines, extensions to the notations given, algorith
23、ms for conversions between the textual and metamodel presentations of abstract grammars, mappings to XML-based concrete syntaxes for interchange formats, and the possibility of further formal notations, such as a formal notation for specifying constraints. Associated work: This Recommendation is gen
24、erally associated with the study of formal languages for telecommunications applications in ITU-T, in particular the languages defined by the X.680 series, Z.100 series, Z.120 series, Z.150 series and Z.160/Z.170 series of ITU-T Recommendations. This Recommendation is also related to the unified mod
25、elling language (UML) and meta object facility (MOF) work of the object management group (OMG). Background: Before the introduction of this Recommendation, the language Recommendations defined by ITU-T used different ways of describing the syntax and semantics of languages. This hinders the understa
26、nding, verifiability, and maintainability of these languages, and prevents their simple harmonization. Some language Recommendations have used grammars in Backus-Naur Form (BNF) to define concrete syntaxes and, in some cases, abstract syntaxes. More recent language definitions have used MOF metamode
27、ls to capture several aspects of languages. In both approaches, there has been a separation of abstract grammar from the concrete notation with a defined relationship between them. Each approach has its benefits and drawbacks. MOF metamodels are appealing due to their graphical nature (where associa
28、tions and inherited concepts are explicit), whereas BNF grammars are easily analyzable by tools and there is considerable experience in their use. This Recommendation gives guidelines for the definition of MOF-based metamodels describing languages in a way that is compatible with the approaches base
29、d on BNF grammars. Traditional BNF-based grammars usually lack some of the capabilities of the MOF approach such as inheritance. MOF and UML-based meta-metamodels contain many features that make metamodels unnecessarily complex, difficult to understand semantically, and difficult to map to BNF gramm
30、ars. This Recommendation focuses on a subset of modelling features that is expressive enough to describe language metamodels and that is isomorphic between the two approaches. Rec. ITU-T Z.111 (04/2016) 1 Recommendation ITU-T Z.111 Notations and guidelines for the definition of ITU-T languages 1 Sco
31、pe This Recommendation provides notation and guidelines for the definition of formal languages defined in new and optionally in revised language Recommendations that define formal languages or description techniques (such as those listed in clause 3.1.2 of the Recommendation “Criteria for use of for
32、mal description techniques by ITU-T“ b-ITU-T Z.110). 1.1 Objective The objective is to provide a basis for a common structure and meta-grammar notations to be used in formal language Recommendations, so that it is not necessary for each language Recommendation to describe its structure and the meta-
33、grammars used: instead each language Recommendation can contain a reference to this Recommendation. By using a common structure and meta-grammar notations, it is also easier to integrate the different formal languages, therefore making it easier to use the languages together both with and without th
34、e support of tools. The use of a common structure and meta-grammar notations makes it easier to build tools that combine the ITU-T languages with each other and other notations. The use of a common structure and meta-grammar notations in different formal language Recommendations also makes it easier
35、 to understand several formal language Recommendations, because the structure and meta-grammar only has to be learnt once. 1.2 Application When a new Recommendation is being drafted for a formal language, the application of this Recommendation should be applied. If it is decided not to apply this Re
36、commendation, the reasons should be stated in the formal language Recommendation. When a Recommendation for an existing formal language is being revised, the application of this Recommendation should be considered taking into account costs and benefits. If this Recommendation is not applied or is ap
37、plied partially, the revised formal language Recommendation should at least contain a statement explaining that the structure and meta-language notations of the formal language Recommendation predated the approval of this Recommendation. The structure and meta-grammar notations given in this Recomme
38、ndation are also likely to be useful for the definition of other formal languages, not just formal languages defined in ITU-T Recommendations. If it is later decided to consider making a Recommendation for such a formal language, the prior application of this Recommendation will be a benefit. 2 Refe
39、rences The following ITU-T Recommendations and other references contain 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; use
40、rs of this Recommendation are therefore encouraged to investigate the 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 Recommen
41、dation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T T.55 Recommendation ITU-T T.55 (2008), Use of the universal multiple-octet coded character set (UCS). 2 Rec. ITU-T Z.111 (04/2016) OMG UML OMG Unified Modeling Language (OMG UML): Superstructure, version 2.5, f
42、ormal/15-03-01 of the Object Management Group (OMG). 3 Definitions No specific definition is provided in this Recommendation. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations: BNF Backus-Naur Form MOF Meta Object Facility OCL Object Constraint Language OMG Object Man
43、agement Group SDL Specification and Description Language UML Unified Modeling Language XML eXtensible Markup Language 5 Conventions If a language Recommendation conforms to this Recommendation, it conforms to the conventions defined in this clause and therefore these do not need to be repeated in th
44、e language Recommendation. 5.1 Grammars A description only conforms to a Recommendation if it conforms to both the Concrete grammar and Abstract grammar of the corresponding language definition: that is, the description must be both recognizable as the language defined in the Recommendation and have
45、 the same meaning as defined by the Semantics in the Recommendation. If further concrete grammars are defined (in additional clauses, annexes or Recommendations), each of the concrete grammars has a definition of its own syntax and of its relationship to the abstract grammar (that is, how to transfo
46、rm into the abstract syntax). Using this approach, there is only one definition of the semantics of a language: the semantics of each of the concrete grammars is identified via its relationship to the abstract grammar. This approach also ensures that any further grammars are equivalent. For some con
47、structs of the concrete grammar, there may be no directly equivalent abstract syntax. In these cases, a Model is given for the transformation from concrete syntax into the concrete syntax of other constructs that (directly or indirectly via further models) have an abstract syntax. Items that have no
48、 mapping to the abstract syntax (such as comments) do not have any formal meaning. 5.2 Basic definitions Some general concepts and conventions are used throughout a language Recommendation; their definitions are given in the following subclauses. 5.3 Presentation style The following presentation sty
49、le is used to separate the different language issues under each topic. Rec. ITU-T Z.111 (04/2016) 3 5.3.1 Division of text A language Recommendation is organized by language features described by an optional introduction, which by convention shall be informative rather than normative (see clause 5.3.2), followed by titled enumeration items for: a) Abstract grammar Described by abstract syntax (either a textual grammar or a graphical metamodel) and static conditions (that is, static constraints) for a model in the language to be we
