1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS Open Systems Interconnection - General x.21 o (1 1 /93) INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - BASIC REFERENCE MODEL: CONVENTIONS FOR THE DEFINITI
2、ON OF OS1 SERVICES ITU-T Recommendation X.21 O (Previously “CCITT Recommendation”) ITU-T RECMN*X=ZLO 93 = 48bZ59L 0594484 892 = Foreword ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization
3、Sector (ITU-T) is a permanent organ of the ITU. Some 179 member countries, 84 telecom operating entities, 145 scientific and industrial organizations and 38 international organizations participate in ITU-T which is the body which sets world telecommunications standards (Recommendations). The approva
4、l of Recommendations by the Members of ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, 1993). In addition, the World Telecommunication Standardization Conference (WTSC), which meets every four years, approves Recommendations submitted to it and establishes the study p
5、rogramme for the following period. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. The text of ITU-T Recommendation X.210 was approved on 16th of November 1993. The identical text is also publis
6、hed as ISO/IEC International Standard 1073 1. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1994 All rights reserved. No part of this publication may be reproduced or u
7、tilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*X=210 73 W 48b2571 0594485 729 W Contents Page . Summary . 111 i Scope 2 Normative references . Identical Recommendations and Intemational Stan
8、dards . Paired Recommendations I International Standards equivalent in technical content 2.1 2.2 3 Definitions Terms defined in the OS1 Basic Reference Model Terms defined in the Application Layer Structure Terms defined in this Recommendation I International Standard . 3.1 3.2 3.3 4 Abbreviations .
9、 SECTION 1 - GENERAL MODEL AND CONVENTIONS 5 Model of service . 5.1 5.2 5.3 5.4 5.5 The concept of OSI-service definition The general model of an OSI-service definition . Categories of facilities within an OSI-service Structure of OSI-service primitives 6.1 OSI-service primitives Properties of OSI-s
10、ervice primitives . Names of OSI-service primitives 6.4 OSI-service primitive parameters . 7 OSI-service definition techniques Conventions for time-sequence diagrams . SECTION 2 - THE APPLICATION LAYER . 8 Model of OSI-service for the Application Layer . 9 The concepts of requestor and acceptor Appl
11、ication of the model to various types of communication 6 6.2 6.3 7.1 7.2 Definition of OSI-local views and their relations . OSI-service primitives in the Application Layer 9.1 Names of OSI-service primitives in the Application Layer SECTION 3 - LAYERS 1-6 . 10 11 Model of OSI-service for layers 1-6
12、 OSI-service primitives in layers 1-6 . 1 1.1 Names of OSI-service primitives in layers 1-6 . 1 3 3 9 9 10 12 12 12 12 12 12 12 12 -T Rec . X.210 (1993 E) . 1 ITU-T RECMN*X=ZLO 93 = 48b259L 059448b bb5 Annex A . Conventions for naming OSI-service primitives . A.l Service-user-name . A.2 Service-prim
13、itive-nae . A.3 OSI-service primitive type A.4 Abbreviated names of OSI-service primitive types Annex B - Conventions for parameter description . Annex C - Correlations between OSI-service primitives at different OSI-local views Annex D - Alternative and additional time-sequence diagrams for two-par
14、ty communications Annex E - Examples of use of OSI-service definitions Example of symmetrical service . Example of asymmetrical service . Annex F - Abracadabra service definition F . 1 Introduction . F.2 The States of an OSI-local view . F.3 Abracadabra service - Symmetrical version . F.4 Abracadabr
15、a service - CliendServer version E.l E.2 13 13 13 13 13 14 14 15 16 16 16 17 17 18 19 22 ii ITU-T RM . X.210 (1993 E) ITU-T RECMNJX.2LO 93 = 4862571 0594487 5Tl Summary The service conventions prescribed in this recommendation ensure that the services of OS1 standards are defined in a uniform way, w
16、hich is consistent with the OS1 Reference Model and the application layer structure standard. The text was developed jointly with ISOAEC. The main intent of this revision is to provide extended capabilities, which are useful in specifying services within the application layer and also to allow great
17、er flexibility to accommodate new services among the layers in the future. . ITU-T Rec. X.210 (1993 E) 111 ITU-T RECMN*X.ZLO 73 W 4862571 0574488 438 ISO/IEC 10731 : 1994 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - BASIC REFERENCE MODEL: CO
18、NVENTIONS FOR THE DEFINITION OF OS1 SERVICES 1 Scope This Recommendation I International Standard - establishes definitions of terms and conventions for use by Recommendations I International Standards defining OSI-services within the scope of the Basic Reference Model of Open Systems Interconnectio
19、n; specifies the application of these terms and conventions to the Recommendations I International Standards defining OSI-services within the Application Layer of the Basic Reference Model of Open Systems Interconnection; specifies the application of these terms and conventions to Recommendations I
20、International Standards defining (N)-services for Layers 1 - 6 of the Basic Reference Model of Open Systems Interconnection. - - 2 Normative references The following Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Re
21、commendation and International Standard. At the time of publication, the editions indicated were valid. Ail Recommendations and International Standards are subject to revision, and parties to agreements based on this Recommendation and International Standards are encouraged to investigate the possib
22、ility of applying the most recent editions of the Recommendations and International Standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards. The Telecommunications Standardization Bureau of the ITU maintains a list of the currently valid ITU-T Rec
23、ommendations. 2.1 Identical Recommendations and International Standards - ITU-T Recommendation X.207 (1993) I ISOAEC 9545: 1993, Information Technology - Open Systems Interconnection - Application Layer structure. 2.2 Paired Recommendations I International Standards equivalent in technical content -
24、 - CCITT Recommendation X.200 (1988), Reference model of open systems for CCZTT applications. ISOOEC 7498: 1984, Information technology - Open Systems Interconnection - Basic Reference Model. 3 Definitions For the purposes of this Recommendation I International Standard, the following definitions ap
25、ply. 3.1 Terms defined in the OS1 Basic Reference Model This Recommendation I International Standard builds on the concepts developed in CCITT Rec. X.200 I IS0 7498 and makes use of the following terms defined in that Recommendation I International Standard: a) (N)-connection; b) (N)-connection-endp
26、oint; c) (N)-entity; d) (N)-layer; ITU-T RC. X.210 (1993 E) 1 ITU-T RECMN*X-230 93 4862593 0574489 374 ISOiIEC 10731 : 1994 (E) e) open system; f) (N)-service; g) (N)-service-access-point; h) (N)-subsystem. 3.2 This Recommendation I International Standard makes use of the following terms defined in
27、ITU-T Rec. X.207 (1993) I ISOAEC 9545: Terms defined in the Application Layer Structure a) application-entity-invocation; b) application-service-element; c) application-service-object; d) control function. 3.3 Terms defined in this Recommendation I International Standard NOTE - Several terms in the
28、following list are structured with the prefix “OSI-”. The terms thus prefixed are intended to have a consistent meaning across all layers of OSI, including the Application Layer. In the case of the OSI-services provided by the six lower layers, the prefix “03-” can be replaced by the equivalent pref
29、ix “(N)-” which particularises the concept to the generic (N)-layer. Further particularisation is needed in other OS1 standards, such as replacing “OSI-” with the abbreviation for one of the six lower layers, or replacing “OSI-” with the abbreviation for a particular application-service-element or g
30、roup of application-service- elements which provide an OSI-service within the Application Layer. 3.3.1 boundary between the OSI-service-provider and the OSI-service-users. to provide that behaviour. (N)-layers, (N)-entities, application-service-elements, etc. are components of an OSI-service-provide
31、r. 3.3.2 service to OSI-service-users. OSI-service: The capability of an OSI-service-provider which is provided to OSI-service-users at the NOTE - The OSI-service defines the external behaviour of the OSI-service-provider independent of the mechanisms used OSI-service-provider: An abstract represent
32、ation of the totality of those entities which provide an OSI- 3.3.3 OSI-service. OSI-service-user: An entity in a single open system that makes use of an OSI-service. NOTE - The OSI-service-user makes use of the OSI-service through a collection of OSI-service primitives defined for the 3.3.4 interac
33、tion between an OSI-service-user and its OSI-service-provider. OSI-service primitive; primitive: NOTE - The term “primitive” is used in some documents in place of the preferred form “OSI-service primitive”. An abstract, atomic, implementation-independent representation of an 3.3.5 submit (primitive)
34、: An OSI-service primitive initiated by an OSI-service-user, 3.3.6 deliver (primitive): An OSI-service primitive initiated by an OSI-service-provider. 3.3.7 primitive and as a result may receive one or more deliver primitives. 3.3.8 primitive and as a result may issue one or more submit primitives.
35、requestor: In a particular exchange of OSI-service-primitives, an OSI-service-user that issues a submit acceptor: In a particular exchange of OSI-service-primitives, an OSI-service-user that receives a deliver 3.3.9 3.3.10 3.3.11 3.3.12 3.3.13 request (primitive); requestor.submit (primitive): A sub
36、mit primitive issued by a requestor. indication (primitive); acceptor.deliver (primitive): A deliver primitive received by an acceptor. response (primitive); acceptormbmit (primitive): A submit primitive issued by an acceptor. confirm (primitive); requestmdeliver (primitive): A deliver primitive rec
37、eived by a requestor. OSI-facility: A part of an OSI-service designated within a Recommendation I International Standard. 2 ITU-T RW. X.210 (1993 E) ITU-T RECMNUXmZLO 73 Li862591 0574470 O76 ISODEC 10731 : 1994 (E) NOTES 1 There are existing Recommendations I International Standards for OSI-service
38、definitions which use the form “ .- service” for terms relating to such a designated part of the total OSI-service. The form “.-facility” is to be strongly preferred for all such usages. 2 The term “OSI-facility” defined here is distinguished from the term “facility” (without the qualification “OSI-
39、”) used, for example, in CCI1T Rec. X.25 and ISO/IEC 8208. 3.3.14 3.3.15 3.3.16 3.3.17 OSI-service-provider to the initiating OSI-service-user. 3.3.18 the OSI-service-provider to the initiating OSI-service-user. 3.3.19 provider. 3.3.20 interactions at an OSI-service boundary. for the (N)-subsystem.
40、3.3.21 is only one type of OSI-local view). 3.3.22 (i.e. there are several types of OSI-local view). 3.3.23 service-users. OSI-mandatory-facility: An OSI-facility which is always provided. OSI-provider-optional-facility: An OSI-facility which may or may not be provided. OSI-user-optional-facility: A
41、n OSI-facility which is only used if all peer OSI-service-users agree. OSI-confirmed-facility: An OSI-facility in the operation of which an explicit confirmation is giver, from the OSI-non-confirmed-facility: An OSI-facility in the operation of which no explicit confirmation is given from OSI-provid
42、er-initiated-facility: An OSI-facility the operation of which is initiated by the OSI-service- OSI-local view: The shared behaviour of an OSI-service-user and an OSI-service-provider in terms of their NOTE - In the case of (N)-services, the OSI-service boundary is to be understood as the set of (N)-
43、service-access-pints symmetrical service: An OSI-service for which the definitions of all OSI-local views are the same (Le. there asymmetrical service: An OSI-service for which the definitions of all OSI-local views are not all the same multi-peer: A mode of operation of an OSI-service which support
44、s exchanges between more than two OSI- 4 Abbreviations ASE application-service-element ASO application-service-object OS1 Open Systems Interconnection SECTION 1 - GENERAL MODEL AND CONVENTIONS 5 Model of service 5.1 5.1.1 boundary between the OSI-service-provider and the OSI-service-users. 5.1.2 An
45、OSI-service definition is the complete expression of the behaviour of an OSI-service-provider as seen by its OSI-service-users. An OSI-service definition does not describe the internal behaviour of an OSI-service-provider. There are many mechanisms that may be specified to provide an OSI-service. It
46、 is thus fundamental that the conventions used to define an OSI-service allow an OSI-service definition to be expressed totally independently from any subsequent specification of the protocol or protocols which support that OSI-service. 5.1.3 To make proper use of an OSI-service, it is necessary for
47、 an OSI-service-user to reference the OSI-service definition. As a result, an OSI-service definition constrains the behaviour of the OSI-service-users. Nevertheless, it is not the purpose of an OSI-service definition to express the complete behaviour of OSI-service-users. The concept of OSI-service
48、definition An OSI-service is that capability of an OSI-service-provider which is offered to OSI-service-users at the ITU-T Rec. X.210 (1993 E) 3 ITU-T RECMN*X-210 93 = 4862591 0594493 T22 ISO/IEC 10731 : 1994 (E) 5.2 5.2.1 communication (connectionless-mode, connection-mode, multi-peer. etc.) in all
49、 seven layers. The general model of an OSI-service definition This clause describes a general model for the definition of an OSI-service which is applicable to all modes of 5.2.2 An OSI-service-user and an OSI-service-provider interact at a OSI-service boundary in an open system. The interactions between the OSI-service-user and the OSI-service-provider constitute an abstract interface at the OSI- service boundary. This abstract interface is the OSI-local view. The OSI-local view is defined in terms of the set of OSI- service primitives which the OSI-service user and the OSI-service-pro
