1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Z.121TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2003) SERIES Z: LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS Formal description techniques (FDT) Message Sequence Chart (MSC) Specification and Description Language (SDL) dat
2、a binding to Message Sequence Charts (MSC) ITU-T Recommendation Z.121 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 tech
3、niques Z.110Z.119 Message Sequence Chart (MSC) Z.120Z.129 Extended Object Definition Language (eODL) Z.130Z.139 Tree and Tabular Combined Notation (TTCN) Z.140Z.149 User Requirements Notation (URN) Z.150Z.159 PROGRAMMING LANGUAGES CHILL: The ITU-T high level language Z.200Z.209 MAN-MACHINE LANGUAGE
4、General principles 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-computer interfaces for the management of telecommunication
5、s networks Z.360Z.369 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 Distributed processing environment Z.600Z.609 For further details, please refer to the list o
6、f ITU-T Recommendations. ITU-T Rec. Z.121 (02/2003) i ITU-T Recommendation Z.121 Specification and Description Language (SDL) data binding to Message Sequence Charts (MSC) Summary This Recommendation provides a Specification and Description Language (Z.100) instantiation of both the syntactic and se
7、mantic elements of the Message Sequence Chart (Z.120) data interface, defines the default types, and also the syntax for allowable SDL data definitions that may be used in an MSC Document. Source ITU-T Recommendation Z.121 was prepared by ITU-T Study Group 17 (2001-2004) and approved under the WTSA
8、Resolution 1 procedure on 13 February 2003. ii ITU-T Rec. Z.121 (02/2003) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T
9、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 four years, establishes the topics for study
10、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, the necessary standards are prepared on a col
11、laborative 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. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or impl
12、ementation 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 asserted by ITU members or others outside of the Recommendation development proces
13、s. 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, implementors are cautioned that this may not represent the latest information and are therefore strongly
14、urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Z.121 (02/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Syntactic Interface 1 3.1 Language dec
15、laration 1 3.2 Parenthesis and escape declarations . 2 3.3 Data declaration and use. 2 3.4 Default data types and wildcards 2 4 Semantic interface 3 4.1 Well-formedness definitions 3 4.2 Static semantics interface functions . 4 4.2.1 Tc1, Data definition strings 4 4.2.2 Tc2, Type reference strings 4
16、 4.2.3 Tc3, Expression Strings 5 4.2.4 Tc4, Typed expression strings 6 4.2.5 EqVar, Equal variable strings. 6 4.3 Dynamic semantics interface functions 6 4.3.1 Vars, Extract variables 7 4.3.2 Replace, Variable replacement. 7 4.3.3 NewVar, New variable . 7 4.3.4 Eval, Evaluation of expressions . 8 5
17、Example 9 5.1 Use of default SDL interface 9 iv ITU-T Rec. Z.121 (02/2003) Introduction The data binding of SDL to MSC is provided in two parts. The first describes the syntactic part of the interface, which defines MSC document statements relating to the use of SDL as the data language, and the sec
18、ond describes the semantic part of the interface. The latter consists of the definition of a number of functions that are used to perform the syntactic, static semantic, and dynamic semantic evaluation of SDL data used in MSC. ITU-T Rec. Z.121 (02/2003) 1 ITU-T Recommendation Z.121 Specification and
19、 Description Language (SDL) data binding to Message Sequence Charts (MSC) 1 Scope This Recommendation provides a Specification and Description Language (Z.100) instantiation of the data interface for Message Sequence Chart (Z.120) that is defined to be the default for Z.120. The MSC Z.120 Recommenda
20、tion has an open data interface that permits different users of the language to adopt different data languages for use within MSC diagrams and documents. ITU-T Rec. Z.121 defines a binding of the open interface to a fragment of SDLs data language, which is to be used as the default data language. Th
21、at is, in the absence of an explicit instantiation of the data interface in an MSC document, the binding defined by this Recommendation is to be assumed, as is the language of allowable data definition strings. This is the first version of ITU-T Rec. Z.121, based on the data interface definition tha
22、t first appeared in the current ITU-T Rec. Z.120, published in 1999. 2 References 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 v
23、alid. All Recommendations and other references are subject to revision; users 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 Recommendatio
24、ns is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation Z.100 (2002), Specification and Description Language (SDL). ITU-T Recommendation Z.120 (1999), Message Sequence Chart (M
25、SC). 3 Syntactic interface The MSC document provides a statement to declare the name of the data language used, so that tools supporting more than one language may distinguish them. It also provides statements to declare the parenthesis sequences used by the data language so that tools may correctly
26、 identify the extent of any data string embedded in an MSC. In this clause the default statements for the SDL data binding are given. The language declaration is done within a data definition, which also contains the wanted data declarations: data types (with methods and operators), syntypes and syn
27、onyms. 3.1 Language declaration The language declaration may be the given in the MSC document, and it identifies which data language is used throughout the MSCs in the scope of the enclosing MSC document. The following language declaration is defined for SDL, although being the default its use is op
28、tional: language SDL; If this language declaration is given, the parenthesis and escape declarations are implicitly declared and thus not needed to be explicitly given in each MSC document, as are the default types together with their corresponding wildcards. 2 ITU-T Rec. Z.121 (02/2003) 3.2 Parenth
29、esis and escape declarations When SDL data is used in MSC according to the language declaration above, the following parenthesis and escape declarations are assumed: parenthesis nestable (), , (), ; nonnestable /*/, /#/, ; equalpar /; escape ?; ; This declaration means that: the native Z.100 s and s
30、 (/# a comment #/ and /* a note */) are accepted in data strings; Z.100 qualifiers (for example, ) may be used to resolve name conflicts; Z.100 character strings (hello world!) are allowed in expression strings, using the native Z.100 form of a repeated apostrophe () to allow a single apostrophe in
31、a string; ? is used as a general escape to allow the MSC stop tokens in the data strings. If an MSC token that can denote the end of a data string, such as a semi-colon, is to be used openly within the data string, then it must be escaped with the ? character. By used openly we mean that it is not h
32、idden within a pair of the SDL declared parenthesis. For example, a semi-colon does not need to be escaped when it occurs within an SDL string because it is hidden by the string delimiter characters. The only SDL token that needs to escaped in an SDL context is a single quote within a string express
33、ion. SDL strings do not require any special treatment when used within an MSC data string. An MSC parser looks for the longest match of parenthesis. An example: both (. and ( are nestable parenthesis, so the parser would detect incorrect nesting of these parentheses. 3.3 Data declaration and use The
34、 actual data type declarations in the native data language are done within the open string in an MSC document. The next clause describes the allowed SDL syntax within this string. Since SDL s in general allow constructs that may introduce side-effects, the expression permitted in MSC will be constra
35、ined, in particular they shall not contain: ; ; . SDL comments ( and ) can be embedded in any of the MSC terminal strings. The static semantic functions defined in clause 4, define which SDL s are allowable in an MSC. 3.4 Default data types and wildcards When MSC is used with SDL data according to t
36、he language declaration in 3.1, the SDL package Predefined is assumed, so the predefined data types can be referenced from or and predefined operators may be referenced inside an . ITU-T Rec. Z.121 (02/2003) 3 MSC requires the data types Boolean, natural and time (see 5.11/Z.120). The corresponding
37、data types in ITU-T Rec. Z.100 to be used as defaults are: value type Boolean; syntype Natural; value type Time. For each of these default types, a default wildcard is implicitly declared as follows: wildcards anyB: Boolean; anyN: Natural; anyT: Time. 4 Semantic interface The semantic interface is d
38、efined in three parts: well formedness, describing the grammar of allowable SDL data strings to be used in MSC; static semantics, identifying the type correctness requirements of well-formed SDL data strings; dynamic semantics, defining how to evaluate well-formed and type correct SDL expression str
39、ings used in MSC. 4.1 Well-formedness definitions The data interface specifies four functions, Wf1, , Wf4 that are required to define the syntactically valid data strings. Table 4-1 identifies the SDL grammar that corresponds to the valid data strings. For example, Wf1(v) is true if and only if v is
40、 a string that can be produced by the SDL grammar rule for . The strings can contain SDL comments in the normal way so that the definitions apply to any string following the filtering of any comments as defined by or . Table 4-1/Z.121 Mapping of MSC data interface strings Well-formedness function na
41、me MSC terminal string SDL grammar Wf1 Wf2 * Wf3 Wf4 In the case of data definition strings, Wf2, the legal strings have to be defined by an auxiliary grammar rule in terms of the SDL production , since there does not exist an SDL production that corresponds to the requirement. The rule permits any
42、sequence of enclosed by a pair of braces (defined as and ). The braces save having to escape any semicolon characters appearing in the data definitions, since a semicolon acts as the delimiting character for the data definition string itself. Thus, a valid forms a valid SDL package body being a subs
43、et of the allowable items in a package. 4 ITU-T Rec. Z.121 (02/2003) 4.2 Static semantics interface functions The data interface specifies four predicates, Tc1, , Tc4, one per data string class, that are required to assert that the static semantics of valid data strings are upheld. That is, the pred
44、icates will only be applied to strings that satisfy their corresponding well-formedness function. The static semantic rules that will determine the four predicates are described in 6.3/Z.100 and clause 12/Z.100. There is also EqVar, an auxiliary relation, required by the data interface used to ident
45、ify equivalence between variable strings. 4.2.1 Tc1, Data definition strings Tc1(d) is true of a syntactically valid data string d i.e., Wf2(d) is true if it satisfies the static semantics of SDL as defined in 6.3/Z.100. In particular, if a package body consisting of the string d, minus its enclosin
46、g braces, satisfies the syntax and static semantics of SDL packages, then Tc1(d) is true, and vice versa. This is illustrated in Figure 4-1 where the data string “ D “ satisfies Tc1 only when the SDL package is statically correct. mscdocument M.data D ;.package MDFigure 4-1/Z.121 Equivalent SDL stat
47、ic requirements for data string 4.2.2 Tc2, Type reference strings Tc2(d)(t) is true of a syntactically valid data string d and type reference string t i.e., Wf2(d) and Wf3(t) are true if and only if: Tc1(d), i.e., d conforms to the static semantics for SDL data; t is statically correct in the contex
48、t of data string d according to the static rules of SDL. The latter requirement is equivalent to saying that a declaration of a variable of having type t in the context of a package containing d (minus enclosing braces) is statically correct. This is illustrated in Figure 4-2 where the example type
49、reference string t of an MSC variable declaration satisfies Tc2(d) only when the SDL process is statically correct. The package referenced by the SDL process is constructed as per Figure 4-1. ITU-T Rec. Z.121 (02/2003) 5 mscdocument M.inst I variables x: t;.data d;.use M;process Idcl x t;Figure 4-2/Z.121 Equivalent SDL static requirements for type reference string 4.2.3 Tc3, Expression Strings Tc3(d)(S)(e) is true of a syntactically valid data string d and expressi
