1、CCITT RECMN*X-ZLB 93 = 48b259L 0577883 455 1 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU OPEN SYSTEMS INTERCONNECTION - GENERAL SERVICE DEFINITIONS X.218 (03/93) RELIABLE TRANSFER: MODEL AND SERVICE DEFINITION ITU-T Recommendation X.218 (Previously “CC
2、IlT Recommendation”) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMNJX-ZL8 93 m 4862593 0577884 393 m FOREWORD The Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- municatio
3、n Union. The 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 Conference (WTSC), which meets every four years, established
4、the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. -T Recommendation X.218 was revised by the ITU-T Study Group VI1 (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the
5、 International Telecommunication Union (ITU), the CCIT ceased to exist ils of 28 February 1993. In its place, the Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, tbe CCIR and the IFRB have been replaced by the Radiocommunication Sec
6、tor. In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR, or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper term
7、inology related to the new IT structure. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized
8、in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMNtX.ZL8 93 4862591 0577885 228 m CONTENTS
9、 introduction . 1 2 References 3 Definitions 4 Abbreviations . 5 Conventions 6 Reliable Transfer model . Scope and field of application 7 Overview of service . 8 Relationship with other ASES and Lower Layer services 9 Service definition . 10 Sequencing information . U 1 1 2 3 4 4 5 6 7 14 Recommenda
10、tion X.218 (03/93) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*X-Z18 93 m 48b259L 057788b 164 m INTRODUCTION This Recommendation defines the services provided by application-service-element - the Reliable Transfer Serv
11、ice Element (RTSE) - to provide for the Reliable Transfer of application-protocoldata-units (APDUs) between open systems. This Recommendation is one of a set of Recommendations defining sets of application-serviceelements commonly used by a number of applications. Reliable Transfer provides an appli
12、cation-independent mechanism to recover from communication and end-system failure minimizing the amount of retransmission. This Recommendation is technically aligned with IS0 9066- 1. u Recommendation X.218 (03/93) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by In
13、formation Handling ServicesCCITT RECNN*X*ZLB 93 = 9862.591 0577887 OTO D Recommendation X.218 RELIABLE TRANSFER: MODEL AND SERVICE DEFINITIONI) (Melbourne, 1988; revised Helsinki, 1993) The CCIT, considering (a) that Recommendation X.200 defines the Basic Reference Model of Open Systems Interconnect
14、ion (OSI) for CCIIT applications; (b) that Recommendation X.210 defines the service conventions for describing the services of the OS1 reference model; (c) that Recommendation X.216 defines the Presentation Layer service; (d) that Recommendation X.217 defines the Association Control service; (e) tha
15、t Recommendation X.228 defines the Reliable Transfer protocol; (f) that there is a need for common Reliable Transport support for various applications, unanimously declares Applications as given in the Scope and field of application. that this Recommendation defines the Reliable Transfer service of
16、Open Systems Interconnection for CCIT 1 This Recommendation defines the services provided by the Reliable Transfer Service Element (RTSE). The RTSE services are provided by the use of the RTSE protocol (Recommendation X.228) in conjunction with the Association Control Service Element (ACSE) services
17、 (Recommendation X.217) and the ACSE protocol (Recommendation X.227), and the presentation-service (Recommendation X.216). No requirement is made for conformance to this Recommendation. Scope and field of application 2 References The following Recommendations, and other references contain provisions
18、 which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. AU Recommendations and other references are subject to revision; d users of this Recommendation are therefore encouraged to investigate the possibility
19、 of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid Recommendations is regularly published. Recommendation X.200, Reference Model of Open Systems Interconnection for CCIT Applications (see also IS0 7498). Recommendation X.208,
20、Specijication of abstract syntax nofation (see also IS0 8824). Recommendation X.209, Specification of Basic Encoding Rules for the absrract syntax notation (see also IS0 8825). Recommendation X.210, Open Systems Interconnection Layer Service Definition Conventions (see also ISO/TR 8509). Recommendat
21、ion X.216, Presentation Service Definition for Open Systems Interconnection for CCIT Applications (see also IS0 8822). i) Recommendation X.218 and IS0 9066-1 Information processing systems - Text Communication - Reliable Transfer - Part i: Model and Service Definition were developed in close collabo
22、ration and are technically aligned. Recommendation X.218 (03193) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*X-218 73 4862571 0577888 T37 D Recommendation X.217, Association Control Service Definition for CCTApplicatio
23、ns (see also IS0 8649). Recommendation X.227, Association Control Protocol Spec$cation for CCiT Applications (see also IS0 8650). Recommendation X.228, Reliable Transfer: Protocol SpecrJication (see also IS0 9066-2). 3 Definitions 3.1 Reference model definitions This Recommendation is based on the c
24、oncepts developed in Recommendation X.200 and makes use of the following terms defined in it: Application Layer; application-process ; application-entity ; application-service-element; application-protocol-data-unit; application-protocol-control-information; Presentation Layer; presentation-service;
25、 presentation-connection ; session-service; session-connection; transfer syntax; two-way-alternate interaction; and user-element. 3.2 Service convention definitions This Recommendation makes use of the following terms defined in Recommendation X.210: service-provider; service-user; confmed service;
26、non-confumed service; provider-initiated service; service-primitive; primitive; request (primitive); indication (primitive); response (primitive); and confm (primitive). 3.3 Presentation service definitions This Recommendation makes use of the following terms defined in Recommendation X.216: a) absr
27、ractsyntax; b) abstract syntax name; c) default context; d) presentation context; e) transfer syntax name. 2 Recommendation X.218 (03/93) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*X=218 93 = 48b259L 0577889 973 m 3.4 A
28、ssociation control definitions This Recommendation makes use of the following terms defined in Recommendation X.217: a) application-association; association; b) application context; c) Association Conuol Service Element; d) X.4 10- 1984 mode. 35 Reliable transfer definitions For the purpose of this
29、Recommendation, the following definitions apply: 3.5.1 association-initiating-application-entity; association-initiator: The application-entity that initiates the application-association. 3.5.2 the initiation of an application-association by another AE. 3.5.3 the APDU to the receiving application-en
30、tity. 3.5.4 possess the Turn) the APDU From the sending application-entity. 3.5.5 a particular RTSE service. 3.5.6 for a particular RTSE service. 3.5.7 Reliable Transfer Service Element: The application-service-element defined in this Recommendation. 3.5.8 Reliable Transfer: An application-independe
31、nt mechanism to provide for the transfer of application-protocol- data-units between open systems, and to recover from communication and end-system failure minimizing the amount of retransmission. 3.5.9 RTSE-user: The user of the Reliable Transfer Service Element. The user may he the user element, o
32、r another application service element, of the application entity. 3.5.10 RTSE-provider: The provider of the Reliable Transfer Service Element. 3.5.11 ACSEprovider: The provider of the Association Control Service Element. 3.5.12 monologue interaction: A mode of interaction where only one application-
33、entity may be the sender. 3.5.13 syntax-matching services: Local services provided by Lhe presentation-service provider enabling the transformation from the local representation of an application-protocol-data-unit value into a representation specified by a negotiated transfer syntax and vice versa.
34、 3.5.14 interworking with application-eiitities based on CCITT Recommendation X.410-1984. 3.5.15 association-responding-application-entity; association-responder: The application-entity that responds to sending-application-entity; sender: The application-entity that sends, or may send (.e. possesses
35、 the TURN) receiving-application-entity; receiver: The applicationentity that receives, or may receive (i.e. does not requestor: The part of an application-entity that issues a request primitive, or receives a confirm primitive for acceptor: The part of an application-entity that receives the indica
36、tion primitive, or issues a response pnmitivc X.410-1984 mode: A restricted mode of operation of the Reliable Transfer Service Element to allow normal mode: A mode of operation of the Reliable Transfer Service Element providing full services. 4 Abbreviations For the purpose of this Recommendation th
37、e following abbreviations are used: AE application entity ACSE Association Control Service Element APDU application-protocol-data-unit ASE application-service-element Recommendation X.218 (03/93) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handlin
38、g ServicesCCITT RECMN*X=ZLB 93 4Bb2591 0577890 695 W os1 Open Systems Interconnection RT (or RTS) Reliable Transfer RTSE Reliable Transfer Service Element 5 Conventions This Recommendation defines services for the RTSE following the descriptive conventions defined in RecommendationX.210. In 9, the d
39、efinition of each RTSE service includes a table that lists the parameters of its primitives. For a given primitive, the presence of each parameter is described by one of the following values. Blank not applicable M mandatory U user option C conditional T A P presence is an RTSE-provider option prese
40、nce subject to conditions defined in Recommendation X.217 presence subject to conditions defined in Recommendation X.216 in addition, the notation (=) indicates that a parameter value is semantically equal to the value to its left in the table. 6 Reliable Transfer model In the OS1 environment, commu
41、nication between application-processes is represented in terms of communication between a pair of application-entities (AEs) using the presentation-service. Communication between some application- entities requires the Reliable Transfer of application-protocol-data-units (APDUs). APDUs sent by one A
42、E (the sender) are received by the other AE (the receiver). Reliable Transfer ensures that each APDU is completely transferred between AEs exactly once, or that the sending AE is warned of an exception. Reliable Transfer recovers from communication and end-system failure and minimizes the amount of
43、retransmission needed for recovery. The APDUs transferred are transparent to the Reliable Transfer. Reliable Transfer is carried out within the context of an application-association. An application-association defines the relationship between a pair of AEs, and is formed by the exchange of applicati
44、on-protocol-control-information through the use of presentation-services. The AE that initiates an application-association is called the association-initiating AE, or the association-initiator, while the AE that responds to the initiation of an application-association by another AE is called the ass
45、ociation-responding AE, or the association-responder. Only the association-initiator may release an established application-association. The functionality of an AE is factored into one user-element and a set of association-service-elements (ASEs). Each ASE may itself be factored into a set of (more
46、primitive) ASEs. The interaction between AEs is described in terms of their use of ASEs. The specific combination of a user-element and the set of ASEs which comprise an AE are defined by the association context. Figure 1 illustrates an example of an application context involving the Reliable Transf
47、er Service Element (RTSE). The ASEs available to the user-element require communication over an application-association. The control of that application-association (establishment, release, abort) and the Reliable Transfer of APDUs over the application- association is performed by the Reliable Trans
48、fer Service Element (RTSE) defined in this Recommendation. The RTSE uses the Association Control Service Element (ACSE) defined in Recommendation X.217 for control of that application- association (establishment, release, abort). Note that the application context depicted in Figure 1 is minimal for
49、an application context involving RTSE. Another example, taken from message handling (Recommendation X.400), of an application context involving RTSE, could be that of a message transfer agent (MTA), and would include the message transfer service element (MTSE) in addition to the ACSE and the RTSE. Note also that, in general, it is the responsibility of a Recommendation defining a set of ASEs that make use of the RTSE (and the ACSE), to define what use is made of the RTSE and any restrictions that may apply. 4 Recommendation X.218 (03/93) COPYRIGHT International Telec
