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 X.681 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2015) SERIES X: DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY OSI networking and system aspects Abstract Syntax Notation One (ASN.1) Information technology
2、Abstract Syntax Notation One (ASN.1): Information object specification Recommendation ITU-T X.681 ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY PUBLIC DATA NETWORKS Services and facilities X.1X.19 Interfaces X.20X.49 Transmission, signalling and switching X.50
3、X.89 Network aspects X.90X.149 Maintenance X.150X.179 Administrative arrangements X.180X.199 OPEN SYSTEMS INTERCONNECTION Model and notation X.200X.209 Service definitions X.210X.219 Connection-mode protocol specifications X.220X.229 Connectionless-mode protocol specifications X.230X.239 PICS profor
4、mas X.240X.259 Protocol Identification X.260X.269 Security Protocols X.270X.279 Layer Managed Objects X.280X.289 Conformance testing X.290X.299 INTERWORKING BETWEEN NETWORKS General X.300X.349 Satellite data transmission systems X.350X.369 IP-based networks X.370X.379 MESSAGE HANDLING SYSTEMS X.400X
5、.499 DIRECTORY X.500X.599 OSI NETWORKING AND SYSTEM ASPECTS Networking X.600X.629 Efficiency X.630X.639 Quality of service X.640X.649 Naming, Addressing and Registration X.650X.679 Abstract Syntax Notation One (ASN.1) X.680X.699 OSI MANAGEMENT Systems management framework and architecture X.700X.709
6、 Management communication service and protocol X.710X.719 Structure of management information X.720X.729 Management functions and ODMA functions X.730X.799 SECURITY X.800X.849 OSI APPLICATIONS Commitment, concurrency and recovery X.850X.859 Transaction processing X.860X.879 Remote operations X.880X.
7、889 Generic applications of ASN.1 X.890X.899 OPEN DISTRIBUTED PROCESSING X.900X.999 INFORMATION AND NETWORK SECURITY X.1000X.1099 SECURE APPLICATIONS AND SERVICES X.1100X.1199 CYBERSPACE SECURITY X.1200X.1299 SECURE APPLICATIONS AND SERVICES X.1300X.1399 CYBERSECURITY INFORMATION EXCHANGE X.1500X.15
8、99 CLOUD COMPUTING SECURITY X.1600X.1699 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T X.681 (08/2015) i INTERNATIONAL STANDARD ISO/IEC 8824-2 RECOMMENDATION ITU-T X.681 Information technology Abstract Syntax Notation One (ASN.1): Information object specification
9、 Summary Recommendation ITU-T X.681 | ISO/IEC 8824-2 provides the ASN.1 notation which allows information object classes as well as individual information objects and sets thereof to be defined and given reference names. An information object class defines the form of a conceptual table (an informat
10、ion object set) with one column for each field in the information object class, and with each complete row defining an information object. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T X.681 1994-07-01 7 11.1002/1000/3042 1.1 ITU-T X.681 (1994) Amd. 1 1995-04-10 7 11.1002/
11、1000/3043 2.0 ITU-T X.681 1997-12-12 7 11.1002/1000/4444 2.1 ITU-T X.681 (1997) Technical Cor. 1 1999-06-18 7 11.1002/1000/4702 2.2 ITU-T X.681 (1997) Amd. 1 1999-06-18 7 11.1002/1000/4701 2.3 ITU-T X.681 (1997) Amd. 2 2001-10-29 7 11.1002/1000/5564 3.0 ITU-T X.681 2002-07-14 17 11.1002/1000/6086 3.
12、1 ITU-T X.681 (2002) Amd. 1 2003-10-29 17 11.1002/1000/7020 3.2 ITU-T X.681 (2002) Technical Cor. 1 2006-06-13 17 11.1002/1000/8837 3.3 ITU-T X.681 (2002) Technical Cor. 2 2007-05-29 17 11.1002/1000/9106 4.0 ITU-T X.681 2008-11-13 17 11.1002/1000/9605 4.1 ITU-T X.681 (2008) Cor. 1 2011-10-14 17 11.1
13、002/1000/11377 5.0 ITU-T X.681 2015-08-13 17 11.1002/1000/12480 * 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 X.681 (08/201
14、5) 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 Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for s
15、tudying 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 by the ITU-T study g
16、roups 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 collaborative basis wit
17、h 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. However, the Recommendation may contain certain mandatory provi
18、sions (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 negative equivalents are used to express requirements. The use of s
19、uch words does not suggest that compliance with the 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 positi
20、on 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 Recommendation, ITU had not received notice of intellectual property, protect
21、ed 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:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of
22、this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T X.681 (08/2015) iii CONTENTS Page Introduction . iv 1 Scope 1 2 Normative references 1 2.1 Identical Recommendations | International Standards . 1 3 Definitions 1 3.1 Specification of
23、 basic notation 1 3.2 Constraint specification . 1 3.3 Parameterization of ASN.1 specification 1 3.4 Additional definitions 2 4 Abbreviations . 3 5 Convention . 3 6 Notation 3 6.1 Assignments 3 6.2 Types . 3 6.3 Values 4 6.4 Elements 4 7 ASN.1 lexical items 4 7.1 Information object class references
24、. 4 7.2 Information object references 4 7.3 Information object set references 4 7.4 Type field references . 4 7.5 Value field references 4 7.6 Value set field references 5 7.7 Object field references 5 7.8 Object set field references . 5 7.9 Word . 5 7.10 Additional keywords . 5 8 Referencing defini
25、tions . 5 9 Information object class definition and assignment 6 10 Syntax List 9 11 Information object definition and assignment. 12 12 Information object set definition and assignment . 14 13 Associated tables 15 14 Notation for the object class field type . 16 15 Information from objects 18 Annex
26、 A The TYPE-IDENTIFIER information object class . 21 Annex B Abstract syntax definitions 22 Annex C The instance-of type. 23 Annex D Examples . 25 D.1 Example usage of simplified OPERATION class . 25 D.2 Example usage of “ObjectClassFieldType“ 26 D.3 Illustrate usage of objects and object sets 26 An
27、nex E Tutorial annex on the ASN.1 model of object set extension 28 Annex F Summary of the notation 29 iv Rec. ITU-T X.681 (08/2015) Introduction An application designer frequently needs to design a protocol which will work with any of a number of instances of some class of information objects, where
28、 instances of the class may be defined by a variety of other bodies, and may be added to over time. Examples of such information object classes are the “operations“ of Remote Operations Service (ROS) and the “attributes“ of the OSI Directory. This Recommendation | International Standard provides not
29、ation which allows information object classes as well as individual information objects and information object sets thereof to be defined and given reference names. An information object class is characterized by the kinds of fields possessed by its instances. A field may contain: an arbitrary type
30、(a type field); or a single value of a specified type (a fixed-type value field); or a single value of a type specified in a (named) type field (a variable-type value field); a non-empty set of values of a specified type (a fixed-type value set field); or a non-empty set of values of a type specifie
31、d in a (named) type field (a variable-type value set field); or a single information object from a specified information object class (an object field); an information object set from a specified information object class (an object set field). A fixed-type value field of an information object class
32、may be selected to provide unique identification of information objects in that class. This is called the identifier field for that class. Values of the identifier field, if supplied, are required to be unique within any information object set that is defined for that class. They may, but need not,
33、serve to unambiguously identify information objects of that class within some broader scope, particularly by the use of object identifier as the type of the identifier field. An information object class is defined by specifying: the names of the fields; for each field, the form of that field (type,
34、fixed-type value, variable-type value, fixed-type value set, variable-type value set, object, or object set); optionality and default settings of fields; which field, if any, is the identifier field. An individual information object in the class is defined by providing the necessary information for
35、each field. The notation defined herein permits an ASN.1 type to be specified by reference to a field of some information object class the object class field type. In Rec. ITU-T X.682 | ISO/IEC 8824-3, notation is provided to enable this type to be restricted by reference to some specific informatio
36、n object set. It can be useful to consider the definition of an information object class as defining the form of an underlying conceptual table (the associated table) with one column for each field, and with a completed row defining an information object. The form of the table (determined by the inf
37、ormation object class specification) determines the sort of information to be collected and used to complete some protocol specification. The underlying conceptual table provides the link between those specifying information objects of that class and the protocol which needs that information to comp
38、lete its specification. Typically, the actual information object set used to complete a particular protocol specification will be a parameter of that protocol (see Rec. ITU-T X.683 | ISO/IEC 8824-4). The “InformationFromObjects“ notation referencing a specific object or object set (probably a parame
39、ter) can be used to extract information from cells of conceptual tables. This Recommendation | International Standard: Specifies a notation for defining an information object class, and for identifying it with a reference name (see clause 9). Specifies a notation by which the definer of an informati
40、on object class can provide a defined syntax for the definition of information objects of that class; a default notation is provided for classes for which no defined syntax has been defined (see clause 10). Specifies a notation for defining an information object, and for assigning it to a reference
41、name (see clause 11), and provides analogous notation for an object set (see clause 12). Defines the “associated table“ for an object or object set of a class (see clause 13). Rec. ITU-T X.681 (08/2015) v Specifies notation for the object class field type and its values (see clause 14). NOTE These c
42、onstructs enable an ASN.1 type to be specified using a named field of a named information object class. Constraints on that type to restrict it to values related to a specific information object set appear in Rec. ITU-T X.682 | ISO/IEC 8824-3. Specifies notation for extracting information from objec
43、ts (see clause 15). The set of information objects used in defining an object set may be partially or entirely unknown at the time of definition of an ASN.1 specification. Such cases occur, for example, in network management where the set of managed objects varies while the network manager is execut
44、ing. This Recommendation | International Standard specifies the rules for inclusion of an extension marker in the definition of object sets to signal to implementers the intention of the designer that the contents of the object set is not fully defined in the ASN.1 specification. When an object set
45、is defined with an extension marker, the implementer must provide means, possibly outside the scope of ASN.1, for dynamically adding objects to the object set and removing previously added objects from the object set. Annex A, which is an integral part of this Recommendation | International Standard
46、, specifies the information object class whose object class reference is TYPE-IDENTIFIER. This is the simplest useful class, with just two fields, an identifier field of type object identifier, and a single type field which defines the ASN.1 type for carrying all information concerning any particula
47、r object in the class. It is defined herein because of the widespread use of information objects of this form. Annex B, which is an integral part of this Recommendation | International Standard, specifies the notation for defining an abstract syntax (composed of the set of values of a single ASN.1 t
48、ype) by the definition of an appropriate information object. Annex C, which is an integral part of this Recommendation | International Standard, specifies the notation for the instance-of type (the INSTANCE OF notation). Annex D, which is not an integral part of this Recommendation | International S
49、tandard, provides examples on how to use the notation described in this Recommendation | International Standard. Annex E, which is not an integral part of this Recommendation | International Standard, provides a summary of the ASN.1 model of object set extension. Annex F, which is not an integral part of this Recommendation | International Standard, provides a summary of the notation defined herein. ISO/IEC 8824-2 : 2015 (E) Rec. ITU-T X.681 (08/2015) 1 INTERNATIONAL
